[v9,1/3] drm/buddy: Implement tracking clear page feature

Commit Message

Paneer Selvam, Arunpravin March 18, 2024, 9:40 p.m. UTC

- Add tracking clear page feature.

- Driver should enable the DRM_BUDDY_CLEARED flag if it
  successfully clears the blocks in the free path. On the otherhand,
  DRM buddy marks each block as cleared.

- Track the available cleared pages size

- If driver requests cleared memory we prefer cleared memory
  but fallback to uncleared if we can't find the cleared blocks.
  when driver requests uncleared memory we try to use uncleared but
  fallback to cleared memory if necessary.

- When a block gets freed we clear it and mark the freed block as cleared,
  when there are buddies which are cleared as well we can merge them.
  Otherwise, we prefer to keep the blocks as separated.

- Add a function to support defragmentation.

v1:
  - Depends on the flag check DRM_BUDDY_CLEARED, enable the block as
    cleared. Else, reset the clear flag for each block in the list(Christian)
  - For merging the 2 cleared blocks compare as below,
    drm_buddy_is_clear(block) != drm_buddy_is_clear(buddy)(Christian)
  - Defragment the memory beginning from min_order
    till the required memory space is available.

v2: (Matthew)
  - Add a wrapper drm_buddy_free_list_internal for the freeing of blocks
    operation within drm buddy.
  - Write a macro block_incompatible() to allocate the required blocks.
  - Update the xe driver for the drm_buddy_free_list change in arguments.
  - add a warning if the two blocks are incompatible on
    defragmentation
  - call full defragmentation in the fini() function
  - place a condition to test if min_order is equal to 0
  - replace the list with safe_reverse() variant as we might
    remove the block from the list.

v3:
  - fix Gitlab user reported lockup issue.
  - Keep DRM_BUDDY_HEADER_CLEAR define sorted(Matthew)
  - modify to pass the root order instead max_order in fini()
    function(Matthew)
  - change bool 1 to true(Matthew)
  - add check if min_block_size is power of 2(Matthew)
  - modify the min_block_size datatype to u64(Matthew)

v4:
  - rename the function drm_buddy_defrag with __force_merge.
  - Include __force_merge directly in drm buddy file and remove
    the defrag use in amdgpu driver.
  - Remove list_empty() check(Matthew)
  - Remove unnecessary space, headers and placement of new variables(Matthew)
  - Add a unit test case(Matthew)

Signed-off-by: Arunpravin Paneer Selvam <[e-mail]>
Signed-off-by: Matthew Auld <[e-mail]>
Suggested-by: Christian König <[e-mail]>
Suggested-by: Matthew Auld <[e-mail]>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c  |   6 +-
 drivers/gpu/drm/drm_buddy.c                   | 427 ++++++++++++++----
 drivers/gpu/drm/i915/i915_ttm_buddy_manager.c |   6 +-
 drivers/gpu/drm/tests/drm_buddy_test.c        |  18 +-
 drivers/gpu/drm/xe/xe_ttm_vram_mgr.c          |   4 +-
 include/drm/drm_buddy.h                       |  16 +-
 6 files changed, 360 insertions(+), 117 deletions(-)

Comments

Paneer Selvam, Arunpravin March 25, 2024, 1:37 p.m. UTC | #1

Hi Matthew,
ping?

Thanks,
Arun.
On 3/19/2024 3:10 AM, Arunpravin Paneer Selvam wrote:
> - Add tracking clear page feature.
>
> - Driver should enable the DRM_BUDDY_CLEARED flag if it
>    successfully clears the blocks in the free path. On the otherhand,
>    DRM buddy marks each block as cleared.
>
> - Track the available cleared pages size
>
> - If driver requests cleared memory we prefer cleared memory
>    but fallback to uncleared if we can't find the cleared blocks.
>    when driver requests uncleared memory we try to use uncleared but
>    fallback to cleared memory if necessary.
>
> - When a block gets freed we clear it and mark the freed block as cleared,
>    when there are buddies which are cleared as well we can merge them.
>    Otherwise, we prefer to keep the blocks as separated.
>
> - Add a function to support defragmentation.
>
> v1:
>    - Depends on the flag check DRM_BUDDY_CLEARED, enable the block as
>      cleared. Else, reset the clear flag for each block in the list(Christian)
>    - For merging the 2 cleared blocks compare as below,
>      drm_buddy_is_clear(block) != drm_buddy_is_clear(buddy)(Christian)
>    - Defragment the memory beginning from min_order
>      till the required memory space is available.
>
> v2: (Matthew)
>    - Add a wrapper drm_buddy_free_list_internal for the freeing of blocks
>      operation within drm buddy.
>    - Write a macro block_incompatible() to allocate the required blocks.
>    - Update the xe driver for the drm_buddy_free_list change in arguments.
>    - add a warning if the two blocks are incompatible on
>      defragmentation
>    - call full defragmentation in the fini() function
>    - place a condition to test if min_order is equal to 0
>    - replace the list with safe_reverse() variant as we might
>      remove the block from the list.
>
> v3:
>    - fix Gitlab user reported lockup issue.
>    - Keep DRM_BUDDY_HEADER_CLEAR define sorted(Matthew)
>    - modify to pass the root order instead max_order in fini()
>      function(Matthew)
>    - change bool 1 to true(Matthew)
>    - add check if min_block_size is power of 2(Matthew)
>    - modify the min_block_size datatype to u64(Matthew)
>
> v4:
>    - rename the function drm_buddy_defrag with __force_merge.
>    - Include __force_merge directly in drm buddy file and remove
>      the defrag use in amdgpu driver.
>    - Remove list_empty() check(Matthew)
>    - Remove unnecessary space, headers and placement of new variables(Matthew)
>    - Add a unit test case(Matthew)
>
> Signed-off-by: Arunpravin Paneer Selvam <[e-mail]>
> Signed-off-by: Matthew Auld <[e-mail]>
> Suggested-by: Christian König <[e-mail]>
> Suggested-by: Matthew Auld <[e-mail]>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c  |   6 +-
>   drivers/gpu/drm/drm_buddy.c                   | 427 ++++++++++++++----
>   drivers/gpu/drm/i915/i915_ttm_buddy_manager.c |   6 +-
>   drivers/gpu/drm/tests/drm_buddy_test.c        |  18 +-
>   drivers/gpu/drm/xe/xe_ttm_vram_mgr.c          |   4 +-
>   include/drm/drm_buddy.h                       |  16 +-
>   6 files changed, 360 insertions(+), 117 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> index 8db880244324..c0c851409241 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> @@ -571,7 +571,7 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
>   	return 0;
>   
>   error_free_blocks:
> -	drm_buddy_free_list(mm, &vres->blocks);
> +	drm_buddy_free_list(mm, &vres->blocks, 0);
>   	mutex_unlock(&mgr->lock);
>   error_fini:
>   	ttm_resource_fini(man, &vres->base);
> @@ -604,7 +604,7 @@ static void amdgpu_vram_mgr_del(struct ttm_resource_manager *man,
>   
>   	amdgpu_vram_mgr_do_reserve(man);
>   
> -	drm_buddy_free_list(mm, &vres->blocks);
> +	drm_buddy_free_list(mm, &vres->blocks, 0);
>   	mutex_unlock(&mgr->lock);
>   
>   	atomic64_sub(vis_usage, &mgr->vis_usage);
> @@ -912,7 +912,7 @@ void amdgpu_vram_mgr_fini(struct amdgpu_device *adev)
>   		kfree(rsv);
>   
>   	list_for_each_entry_safe(rsv, temp, &mgr->reserved_pages, blocks) {
> -		drm_buddy_free_list(&mgr->mm, &rsv->allocated);
> +		drm_buddy_free_list(&mgr->mm, &rsv->allocated, 0);
>   		kfree(rsv);
>   	}
>   	if (!adev->gmc.is_app_apu)
> diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c
> index c4222b886db7..625a30a6b855 100644
> --- a/drivers/gpu/drm/drm_buddy.c
> +++ b/drivers/gpu/drm/drm_buddy.c
> @@ -38,8 +38,8 @@ static void drm_block_free(struct drm_buddy *mm,
>   	kmem_cache_free(slab_blocks, block);
>   }
>   
> -static void list_insert_sorted(struct drm_buddy *mm,
> -			       struct drm_buddy_block *block)
> +static void list_insert(struct drm_buddy *mm,
> +			struct drm_buddy_block *block)
>   {
>   	struct drm_buddy_block *node;
>   	struct list_head *head;
> @@ -57,6 +57,16 @@ static void list_insert_sorted(struct drm_buddy *mm,
>   	__list_add(&block->link, node->link.prev, &node->link);
>   }
>   
> +static void clear_reset(struct drm_buddy_block *block)
> +{
> +	block->header &= ~DRM_BUDDY_HEADER_CLEAR;
> +}
> +
> +static void mark_cleared(struct drm_buddy_block *block)
> +{
> +	block->header |= DRM_BUDDY_HEADER_CLEAR;
> +}
> +
>   static void mark_allocated(struct drm_buddy_block *block)
>   {
>   	block->header &= ~DRM_BUDDY_HEADER_STATE;
> @@ -71,7 +81,7 @@ static void mark_free(struct drm_buddy *mm,
>   	block->header &= ~DRM_BUDDY_HEADER_STATE;
>   	block->header |= DRM_BUDDY_FREE;
>   
> -	list_insert_sorted(mm, block);
> +	list_insert(mm, block);
>   }
>   
>   static void mark_split(struct drm_buddy_block *block)
> @@ -82,6 +92,114 @@ static void mark_split(struct drm_buddy_block *block)
>   	list_del(&block->link);
>   }
>   
> +static struct drm_buddy_block *
> +__get_buddy(struct drm_buddy_block *block)
> +{
> +	struct drm_buddy_block *parent;
> +
> +	parent = block->parent;
> +	if (!parent)
> +		return NULL;
> +
> +	if (parent->left == block)
> +		return parent->right;
> +
> +	return parent->left;
> +}
> +
> +static unsigned int __drm_buddy_free(struct drm_buddy *mm,
> +				     struct drm_buddy_block *block,
> +				     bool force_merge)
> +{
> +	struct drm_buddy_block *parent;
> +	unsigned int order;
> +
> +	while ((parent = block->parent)) {
> +		struct drm_buddy_block *buddy;
> +
> +		buddy = __get_buddy(block);
> +
> +		if (!drm_buddy_block_is_free(buddy))
> +			break;
> +
> +		if (!force_merge) {
> +			/**
> +			 * Check the block and its buddy clear state and exit
> +			 * the loop if they both have the dissimilar state.
> +			 */
> +			if (drm_buddy_block_is_clear(block) !=
> +			    drm_buddy_block_is_clear(buddy))
> +				break;
> +
> +			if (drm_buddy_block_is_clear(block))
> +				mark_cleared(parent);
> +		}
> +
> +		list_del(&buddy->link);
> +		if (force_merge && drm_buddy_block_is_clear(buddy))
> +			mm->clear_avail -= drm_buddy_block_size(mm, buddy);
> +
> +		drm_block_free(mm, block);
> +		drm_block_free(mm, buddy);
> +
> +		block = parent;
> +	}
> +
> +	order = drm_buddy_block_order(block);
> +	mark_free(mm, block);
> +
> +	return order;
> +}
> +
> +static int __force_merge(struct drm_buddy *mm,
> +			 unsigned int min_order)
> +{
> +	unsigned int order;
> +	int i;
> +
> +	if (!min_order)
> +		return -ENOMEM;
> +
> +	if (min_order > mm->max_order)
> +		return -EINVAL;
> +
> +	for (i = min_order - 1; i >= 0; i--) {
> +		struct drm_buddy_block *block, *prev;
> +
> +		list_for_each_entry_safe_reverse(block, prev, &mm->free_list[i], link) {
> +			struct drm_buddy_block *buddy;
> +
> +			if (!block->parent)
> +				continue;
> +
> +			buddy = __get_buddy(block);
> +			if (!drm_buddy_block_is_free(buddy))
> +				continue;
> +
> +			WARN_ON(drm_buddy_block_is_clear(block) ==
> +				drm_buddy_block_is_clear(buddy));
> +
> +			/**
> +			 * If the prev block is same as buddy, don't access the
> +			 * block in the next iteration as we would free the
> +			 * buddy block as part of the free function.
> +			 */
> +			if (prev == buddy)
> +				prev = list_prev_entry(prev, link);
> +
> +			list_del(&block->link);
> +			if (drm_buddy_block_is_clear(block))
> +				mm->clear_avail -= drm_buddy_block_size(mm, block);
> +
> +			order = __drm_buddy_free(mm, block, true);
> +			if (order >= min_order)
> +				return 0;
> +		}
> +	}
> +
> +	return -ENOMEM;
> +}
> +
>   /**
>    * drm_buddy_init - init memory manager
>    *
> @@ -137,7 +255,7 @@ int drm_buddy_init(struct drm_buddy *mm, u64 size, u64 chunk_size)
>   	offset = 0;
>   	i = 0;
>   
> -	/*
> +	/**
>   	 * Split into power-of-two blocks, in case we are given a size that is
>   	 * not itself a power-of-two.
>   	 */
> @@ -186,11 +304,21 @@ EXPORT_SYMBOL(drm_buddy_init);
>    */
>   void drm_buddy_fini(struct drm_buddy *mm)
>   {
> +	u64 root_size, size;
> +	unsigned int order;
>   	int i;
>   
> +	size = mm->size;
> +
>   	for (i = 0; i < mm->n_roots; ++i) {
> +		order = ilog2(size) - ilog2(mm->chunk_size);
> +		__force_merge(mm, order);
> +
>   		WARN_ON(!drm_buddy_block_is_free(mm->roots[i]));
>   		drm_block_free(mm, mm->roots[i]);
> +
> +		root_size = mm->chunk_size << order;
> +		size -= root_size;
>   	}
>   
>   	WARN_ON(mm->avail != mm->size);
> @@ -223,26 +351,17 @@ static int split_block(struct drm_buddy *mm,
>   	mark_free(mm, block->left);
>   	mark_free(mm, block->right);
>   
> +	if (drm_buddy_block_is_clear(block)) {
> +		mark_cleared(block->left);
> +		mark_cleared(block->right);
> +		clear_reset(block);
> +	}
> +
>   	mark_split(block);
>   
>   	return 0;
>   }
>   
> -static struct drm_buddy_block *
> -__get_buddy(struct drm_buddy_block *block)
> -{
> -	struct drm_buddy_block *parent;
> -
> -	parent = block->parent;
> -	if (!parent)
> -		return NULL;
> -
> -	if (parent->left == block)
> -		return parent->right;
> -
> -	return parent->left;
> -}
> -
>   /**
>    * drm_get_buddy - get buddy address
>    *
> @@ -260,30 +379,6 @@ drm_get_buddy(struct drm_buddy_block *block)
>   }
>   EXPORT_SYMBOL(drm_get_buddy);
>   
> -static void __drm_buddy_free(struct drm_buddy *mm,
> -			     struct drm_buddy_block *block)
> -{
> -	struct drm_buddy_block *parent;
> -
> -	while ((parent = block->parent)) {
> -		struct drm_buddy_block *buddy;
> -
> -		buddy = __get_buddy(block);
> -
> -		if (!drm_buddy_block_is_free(buddy))
> -			break;
> -
> -		list_del(&buddy->link);
> -
> -		drm_block_free(mm, block);
> -		drm_block_free(mm, buddy);
> -
> -		block = parent;
> -	}
> -
> -	mark_free(mm, block);
> -}
> -
>   /**
>    * drm_buddy_free_block - free a block
>    *
> @@ -295,26 +390,59 @@ void drm_buddy_free_block(struct drm_buddy *mm,
>   {
>   	BUG_ON(!drm_buddy_block_is_allocated(block));
>   	mm->avail += drm_buddy_block_size(mm, block);
> -	__drm_buddy_free(mm, block);
> +	if (drm_buddy_block_is_clear(block))
> +		mm->clear_avail += drm_buddy_block_size(mm, block);
> +
> +	__drm_buddy_free(mm, block, false);
>   }
>   EXPORT_SYMBOL(drm_buddy_free_block);
>   
> -/**
> - * drm_buddy_free_list - free blocks
> - *
> - * @mm: DRM buddy manager
> - * @objects: input list head to free blocks
> - */
> -void drm_buddy_free_list(struct drm_buddy *mm, struct list_head *objects)
> +static void __drm_buddy_free_list(struct drm_buddy *mm,
> +				  struct list_head *objects,
> +				  bool mark_clear,
> +				  bool mark_dirty)
>   {
>   	struct drm_buddy_block *block, *on;
>   
> +	WARN_ON(mark_dirty && mark_clear);
> +
>   	list_for_each_entry_safe(block, on, objects, link) {
> +		if (mark_clear)
> +			mark_cleared(block);
> +		else if (mark_dirty)
> +			clear_reset(block);
>   		drm_buddy_free_block(mm, block);
>   		cond_resched();
>   	}
>   	INIT_LIST_HEAD(objects);
>   }
> +
> +static void drm_buddy_free_list_internal(struct drm_buddy *mm,
> +					 struct list_head *objects)
> +{
> +	/**
> +	 * Don't touch the clear/dirty bit, since allocation is still internal
> +	 * at this point. For example we might have just failed part of the
> +	 * allocation.
> +	 */
> +	__drm_buddy_free_list(mm, objects, false, false);
> +}
> +
> +/**
> + * drm_buddy_free_list - free blocks
> + *
> + * @mm: DRM buddy manager
> + * @objects: input list head to free blocks
> + * @flags: optional flags like DRM_BUDDY_CLEARED
> + */
> +void drm_buddy_free_list(struct drm_buddy *mm,
> +			 struct list_head *objects,
> +			 unsigned int flags)
> +{
> +	bool mark_clear = flags & DRM_BUDDY_CLEARED;
> +
> +	__drm_buddy_free_list(mm, objects, mark_clear, !mark_clear);
> +}
>   EXPORT_SYMBOL(drm_buddy_free_list);
>   
>   static inline bool overlaps(u64 s1, u64 e1, u64 s2, u64 e2)
> @@ -327,10 +455,19 @@ static inline bool contains(u64 s1, u64 e1, u64 s2, u64 e2)
>   	return s1 <= s2 && e1 >= e2;
>   }
>   
> +static bool block_incompatible(struct drm_buddy_block *block, unsigned int flags)
> +{
> +	bool needs_clear = flags & DRM_BUDDY_CLEAR_ALLOCATION;
> +
> +	return needs_clear != drm_buddy_block_is_clear(block);
> +}
> +
>   static struct drm_buddy_block *
> -alloc_range_bias(struct drm_buddy *mm,
> -		 u64 start, u64 end,
> -		 unsigned int order)
> +__alloc_range_bias(struct drm_buddy *mm,
> +		   u64 start, u64 end,
> +		   unsigned int order,
> +		   unsigned long flags,
> +		   bool fallback)
>   {
>   	struct drm_buddy_block *block;
>   	struct drm_buddy_block *buddy;
> @@ -369,7 +506,10 @@ alloc_range_bias(struct drm_buddy *mm,
>   
>   		if (contains(start, end, block_start, block_end) &&
>   		    order == drm_buddy_block_order(block)) {
> -			/*
> +			if (!fallback && block_incompatible(block, flags))
> +				continue;
> +
> +			/**
>   			 * Find the free block within the range.
>   			 */
>   			if (drm_buddy_block_is_free(block))
> @@ -391,7 +531,7 @@ alloc_range_bias(struct drm_buddy *mm,
>   	return ERR_PTR(-ENOSPC);
>   
>   err_undo:
> -	/*
> +	/**
>   	 * We really don't want to leave around a bunch of split blocks, since
>   	 * bigger is better, so make sure we merge everything back before we
>   	 * free the allocated blocks.
> @@ -400,30 +540,57 @@ alloc_range_bias(struct drm_buddy *mm,
>   	if (buddy &&
>   	    (drm_buddy_block_is_free(block) &&
>   	     drm_buddy_block_is_free(buddy)))
> -		__drm_buddy_free(mm, block);
> +		__drm_buddy_free(mm, block, false);
>   	return ERR_PTR(err);
>   }
>   
>   static struct drm_buddy_block *
> -get_maxblock(struct drm_buddy *mm, unsigned int order)
> +__drm_buddy_alloc_range_bias(struct drm_buddy *mm,
> +			     u64 start, u64 end,
> +			     unsigned int order,
> +			     unsigned long flags)
> +{
> +	struct drm_buddy_block *block;
> +	bool fallback = false;
> +
> +	block = __alloc_range_bias(mm, start, end, order,
> +				   flags, fallback);
> +	if (IS_ERR(block) && mm->clear_avail)
> +		return __alloc_range_bias(mm, start, end, order,
> +					  flags, !fallback);
> +
> +	return block;
> +}
> +
> +static struct drm_buddy_block *
> +get_maxblock(struct drm_buddy *mm, unsigned int order,
> +	     unsigned long flags)
>   {
> -	struct drm_buddy_block *max_block = NULL, *node;
> +	struct drm_buddy_block *max_block = NULL, *block = NULL;
>   	unsigned int i;
>   
>   	for (i = order; i <= mm->max_order; ++i) {
> -		if (!list_empty(&mm->free_list[i])) {
> -			node = list_last_entry(&mm->free_list[i],
> -					       struct drm_buddy_block,
> -					       link);
> -			if (!max_block) {
> -				max_block = node;
> +		struct drm_buddy_block *tmp_block;
> +
> +		list_for_each_entry_reverse(tmp_block, &mm->free_list[i], link) {
> +			if (block_incompatible(tmp_block, flags))
>   				continue;
> -			}
>   
> -			if (drm_buddy_block_offset(node) >
> -			    drm_buddy_block_offset(max_block)) {
> -				max_block = node;
> -			}
> +			block = tmp_block;
> +			break;
> +		}
> +
> +		if (!block)
> +			continue;
> +
> +		if (!max_block) {
> +			max_block = block;
> +			continue;
> +		}
> +
> +		if (drm_buddy_block_offset(block) >
> +		    drm_buddy_block_offset(max_block)) {
> +			max_block = block;
>   		}
>   	}
>   
> @@ -440,11 +607,29 @@ alloc_from_freelist(struct drm_buddy *mm,
>   	int err;
>   
>   	if (flags & DRM_BUDDY_TOPDOWN_ALLOCATION) {
> -		block = get_maxblock(mm, order);
> +		block = get_maxblock(mm, order, flags);
>   		if (block)
>   			/* Store the obtained block order */
>   			tmp = drm_buddy_block_order(block);
>   	} else {
> +		for (tmp = order; tmp <= mm->max_order; ++tmp) {
> +			struct drm_buddy_block *tmp_block;
> +
> +			list_for_each_entry_reverse(tmp_block, &mm->free_list[tmp], link) {
> +				if (block_incompatible(tmp_block, flags))
> +					continue;
> +
> +				block = tmp_block;
> +				break;
> +			}
> +
> +			if (block)
> +				break;
> +		}
> +	}
> +
> +	if (!block) {
> +		/* Fallback method */
>   		for (tmp = order; tmp <= mm->max_order; ++tmp) {
>   			if (!list_empty(&mm->free_list[tmp])) {
>   				block = list_last_entry(&mm->free_list[tmp],
> @@ -454,10 +639,10 @@ alloc_from_freelist(struct drm_buddy *mm,
>   					break;
>   			}
>   		}
> -	}
>   
> -	if (!block)
> -		return ERR_PTR(-ENOSPC);
> +		if (!block)
> +			return ERR_PTR(-ENOSPC);
> +	}
>   
>   	BUG_ON(!drm_buddy_block_is_free(block));
>   
> @@ -473,7 +658,7 @@ alloc_from_freelist(struct drm_buddy *mm,
>   
>   err_undo:
>   	if (tmp != order)
> -		__drm_buddy_free(mm, block);
> +		__drm_buddy_free(mm, block, false);
>   	return ERR_PTR(err);
>   }
>   
> @@ -524,6 +709,8 @@ static int __alloc_range(struct drm_buddy *mm,
>   			mark_allocated(block);
>   			total_allocated += drm_buddy_block_size(mm, block);
>   			mm->avail -= drm_buddy_block_size(mm, block);
> +			if (drm_buddy_block_is_clear(block))
> +				mm->clear_avail -= drm_buddy_block_size(mm, block);
>   			list_add_tail(&block->link, &allocated);
>   			continue;
>   		}
> @@ -548,7 +735,7 @@ static int __alloc_range(struct drm_buddy *mm,
>   	return 0;
>   
>   err_undo:
> -	/*
> +	/**
>   	 * We really don't want to leave around a bunch of split blocks, since
>   	 * bigger is better, so make sure we merge everything back before we
>   	 * free the allocated blocks.
> @@ -557,14 +744,14 @@ static int __alloc_range(struct drm_buddy *mm,
>   	if (buddy &&
>   	    (drm_buddy_block_is_free(block) &&
>   	     drm_buddy_block_is_free(buddy)))
> -		__drm_buddy_free(mm, block);
> +		__drm_buddy_free(mm, block, false);
>   
>   err_free:
>   	if (err == -ENOSPC && total_allocated_on_err) {
>   		list_splice_tail(&allocated, blocks);
>   		*total_allocated_on_err = total_allocated;
>   	} else {
> -		drm_buddy_free_list(mm, &allocated);
> +		drm_buddy_free_list_internal(mm, &allocated);
>   	}
>   
>   	return err;
> @@ -630,11 +817,11 @@ static int __alloc_contig_try_harder(struct drm_buddy *mm,
>   			list_splice(&blocks_lhs, blocks);
>   			return 0;
>   		} else if (err != -ENOSPC) {
> -			drm_buddy_free_list(mm, blocks);
> +			drm_buddy_free_list_internal(mm, blocks);
>   			return err;
>   		}
>   		/* Free blocks for the next iteration */
> -		drm_buddy_free_list(mm, blocks);
> +		drm_buddy_free_list_internal(mm, blocks);
>   	}
>   
>   	return -ENOSPC;
> @@ -690,6 +877,8 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>   	list_del(&block->link);
>   	mark_free(mm, block);
>   	mm->avail += drm_buddy_block_size(mm, block);
> +	if (drm_buddy_block_is_clear(block))
> +		mm->clear_avail += drm_buddy_block_size(mm, block);
>   
>   	/* Prevent recursively freeing this node */
>   	parent = block->parent;
> @@ -701,6 +890,8 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>   	if (err) {
>   		mark_allocated(block);
>   		mm->avail -= drm_buddy_block_size(mm, block);
> +		if (drm_buddy_block_is_clear(block))
> +			mm->clear_avail -= drm_buddy_block_size(mm, block);
>   		list_add(&block->link, blocks);
>   	}
>   
> @@ -709,13 +900,28 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>   }
>   EXPORT_SYMBOL(drm_buddy_block_trim);
>   
> +static struct drm_buddy_block *
> +__drm_buddy_alloc_blocks(struct drm_buddy *mm,
> +			 u64 start, u64 end,
> +			 unsigned int order,
> +			 unsigned long flags)
> +{
> +	if (flags & DRM_BUDDY_RANGE_ALLOCATION)
> +		/* Allocate traversing within the range */
> +		return  __drm_buddy_alloc_range_bias(mm, start, end,
> +						     order, flags);
> +	else
> +		/* Allocate from freelist */
> +		return alloc_from_freelist(mm, order, flags);
> +}
> +
>   /**
>    * drm_buddy_alloc_blocks - allocate power-of-two blocks
>    *
>    * @mm: DRM buddy manager to allocate from
>    * @start: start of the allowed range for this block
>    * @end: end of the allowed range for this block
> - * @size: size of the allocation
> + * @size: size of the allocation in bytes
>    * @min_block_size: alignment of the allocation
>    * @blocks: output list head to add allocated blocks
>    * @flags: DRM_BUDDY_*_ALLOCATION flags
> @@ -761,8 +967,18 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>   		return -EINVAL;
>   
>   	/* Actual range allocation */
> -	if (start + size == end)
> -		return __drm_buddy_alloc_range(mm, start, size, NULL, blocks);
> +	if (start + size == end) {
> +		err =  __drm_buddy_alloc_range(mm, start, size, NULL, blocks);
> +		if (err) {
> +			order = ilog2(size) - ilog2(mm->chunk_size);
> +			if (mm->clear_avail && !__force_merge(mm, order))
> +				return __drm_buddy_alloc_range(mm, start, size, NULL, blocks);
> +
> +			return err;
> +		}
> +
> +		return err;
> +	}
>   
>   	original_size = size;
>   	original_min_size = min_block_size;
> @@ -786,23 +1002,34 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>   		BUG_ON(order < min_order);
>   
>   		do {
> -			if (flags & DRM_BUDDY_RANGE_ALLOCATION)
> -				/* Allocate traversing within the range */
> -				block = alloc_range_bias(mm, start, end, order);
> -			else
> -				/* Allocate from freelist */
> -				block = alloc_from_freelist(mm, order, flags);
> -
> +			block = __drm_buddy_alloc_blocks(mm, start,
> +							 end,
> +							 order,
> +							 flags);
>   			if (!IS_ERR(block))
>   				break;
>   
>   			if (order-- == min_order) {
> +				/**
> +				 * Try allocation through force merge method
> +				 */
> +				if (mm->clear_avail && !__force_merge(mm, min_order)) {
> +					block = __drm_buddy_alloc_blocks(mm, start,
> +									 end,
> +									 min_order,
> +									 flags);
> +					if (!IS_ERR(block)) {
> +						order = min_order;
> +						break;
> +					}
> +				}
> +
> +				/**
> +				 * Try contiguous block allocation through
> +				 * try harder method.
> +				 */
>   				if (flags & DRM_BUDDY_CONTIGUOUS_ALLOCATION &&
>   				    !(flags & DRM_BUDDY_RANGE_ALLOCATION))
> -					/*
> -					 * Try contiguous block allocation through
> -					 * try harder method
> -					 */
>   					return __alloc_contig_try_harder(mm,
>   									 original_size,
>   									 original_min_size,
> @@ -814,6 +1041,8 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>   
>   		mark_allocated(block);
>   		mm->avail -= drm_buddy_block_size(mm, block);
> +		if (drm_buddy_block_is_clear(block))
> +			mm->clear_avail -= drm_buddy_block_size(mm, block);
>   		kmemleak_update_trace(block);
>   		list_add_tail(&block->link, &allocated);
>   
> @@ -823,7 +1052,9 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>   			break;
>   	} while (1);
>   
> -	/* Trim the allocated block to the required size */
> +	/**
> +	 * Trim the allocated block to the required size
> +	 */
>   	if (original_size != size) {
>   		struct list_head *trim_list;
>   		LIST_HEAD(temp);
> @@ -852,7 +1083,7 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>   	return 0;
>   
>   err_free:
> -	drm_buddy_free_list(mm, &allocated);
> +	drm_buddy_free_list_internal(mm, &allocated);
>   	return err;
>   }
>   EXPORT_SYMBOL(drm_buddy_alloc_blocks);
> @@ -885,8 +1116,8 @@ void drm_buddy_print(struct drm_buddy *mm, struct drm_printer *p)
>   {
>   	int order;
>   
> -	drm_printf(p, "chunk_size: %lluKiB, total: %lluMiB, free: %lluMiB\n",
> -		   mm->chunk_size >> 10, mm->size >> 20, mm->avail >> 20);
> +	drm_printf(p, "chunk_size: %lluKiB, total: %lluMiB, free: %lluMiB, clear_free: %lluMiB\n",
> +		   mm->chunk_size >> 10, mm->size >> 20, mm->avail >> 20, mm->clear_avail >> 20);
>   
>   	for (order = mm->max_order; order >= 0; order--) {
>   		struct drm_buddy_block *block;
> diff --git a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
> index 0d735d5c2b35..942345548bc3 100644
> --- a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
> +++ b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
> @@ -126,7 +126,7 @@ static int i915_ttm_buddy_man_alloc(struct ttm_resource_manager *man,
>   	return 0;
>   
>   err_free_blocks:
> -	drm_buddy_free_list(mm, &bman_res->blocks);
> +	drm_buddy_free_list(mm, &bman_res->blocks, 0);
>   	mutex_unlock(&bman->lock);
>   err_free_res:
>   	ttm_resource_fini(man, &bman_res->base);
> @@ -141,7 +141,7 @@ static void i915_ttm_buddy_man_free(struct ttm_resource_manager *man,
>   	struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
>   
>   	mutex_lock(&bman->lock);
> -	drm_buddy_free_list(&bman->mm, &bman_res->blocks);
> +	drm_buddy_free_list(&bman->mm, &bman_res->blocks, 0);
>   	bman->visible_avail += bman_res->used_visible_size;
>   	mutex_unlock(&bman->lock);
>   
> @@ -345,7 +345,7 @@ int i915_ttm_buddy_man_fini(struct ttm_device *bdev, unsigned int type)
>   	ttm_set_driver_manager(bdev, type, NULL);
>   
>   	mutex_lock(&bman->lock);
> -	drm_buddy_free_list(mm, &bman->reserved);
> +	drm_buddy_free_list(mm, &bman->reserved, 0);
>   	drm_buddy_fini(mm);
>   	bman->visible_avail += bman->visible_reserved;
>   	WARN_ON_ONCE(bman->visible_avail != bman->visible_size);
> diff --git a/drivers/gpu/drm/tests/drm_buddy_test.c b/drivers/gpu/drm/tests/drm_buddy_test.c
> index 2f32fb2f12e7..454ad9952f56 100644
> --- a/drivers/gpu/drm/tests/drm_buddy_test.c
> +++ b/drivers/gpu/drm/tests/drm_buddy_test.c
> @@ -64,7 +64,7 @@ static void drm_test_buddy_alloc_contiguous(struct kunit *test)
>   							   DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>   			       "buddy_alloc didn't error size=%u\n", 3 * ps);
>   
> -	drm_buddy_free_list(&mm, &middle);
> +	drm_buddy_free_list(&mm, &middle, 0);
>   	KUNIT_ASSERT_TRUE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
>   							   3 * ps, ps, &allocated,
>   							   DRM_BUDDY_CONTIGUOUS_ALLOCATION),
> @@ -74,7 +74,7 @@ static void drm_test_buddy_alloc_contiguous(struct kunit *test)
>   							   DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>   			       "buddy_alloc didn't error size=%u\n", 2 * ps);
>   
> -	drm_buddy_free_list(&mm, &right);
> +	drm_buddy_free_list(&mm, &right, 0);
>   	KUNIT_ASSERT_TRUE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
>   							   3 * ps, ps, &allocated,
>   							   DRM_BUDDY_CONTIGUOUS_ALLOCATION),
> @@ -89,7 +89,7 @@ static void drm_test_buddy_alloc_contiguous(struct kunit *test)
>   							    DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>   			       "buddy_alloc hit an error size=%u\n", 2 * ps);
>   
> -	drm_buddy_free_list(&mm, &left);
> +	drm_buddy_free_list(&mm, &left, 0);
>   	KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
>   							    3 * ps, ps, &allocated,
>   							    DRM_BUDDY_CONTIGUOUS_ALLOCATION),
> @@ -101,7 +101,7 @@ static void drm_test_buddy_alloc_contiguous(struct kunit *test)
>   
>   	KUNIT_ASSERT_EQ(test, total, ps * 2 + ps * 3);
>   
> -	drm_buddy_free_list(&mm, &allocated);
> +	drm_buddy_free_list(&mm, &allocated, 0);
>   	drm_buddy_fini(&mm);
>   }
>   
> @@ -170,7 +170,7 @@ static void drm_test_buddy_alloc_pathological(struct kunit *test)
>   							  top, max_order);
>   	}
>   
> -	drm_buddy_free_list(&mm, &holes);
> +	drm_buddy_free_list(&mm, &holes, 0);
>   
>   	/* Nothing larger than blocks of chunk_size now available */
>   	for (order = 1; order <= max_order; order++) {
> @@ -182,7 +182,7 @@ static void drm_test_buddy_alloc_pathological(struct kunit *test)
>   	}
>   
>   	list_splice_tail(&holes, &blocks);
> -	drm_buddy_free_list(&mm, &blocks);
> +	drm_buddy_free_list(&mm, &blocks, 0);
>   	drm_buddy_fini(&mm);
>   }
>   
> @@ -277,7 +277,7 @@ static void drm_test_buddy_alloc_pessimistic(struct kunit *test)
>   
>   	list_del(&block->link);
>   	drm_buddy_free_block(&mm, block);
> -	drm_buddy_free_list(&mm, &blocks);
> +	drm_buddy_free_list(&mm, &blocks, 0);
>   	drm_buddy_fini(&mm);
>   }
>   
> @@ -323,7 +323,7 @@ static void drm_test_buddy_alloc_optimistic(struct kunit *test)
>   							   size, size, &tmp, flags),
>   						  "buddy_alloc unexpectedly succeeded, it should be full!");
>   
> -	drm_buddy_free_list(&mm, &blocks);
> +	drm_buddy_free_list(&mm, &blocks, 0);
>   	drm_buddy_fini(&mm);
>   }
>   
> @@ -358,7 +358,7 @@ static void drm_test_buddy_alloc_limit(struct kunit *test)
>   						drm_buddy_block_size(&mm, block),
>   						BIT_ULL(mm.max_order) * PAGE_SIZE);
>   
> -	drm_buddy_free_list(&mm, &allocated);
> +	drm_buddy_free_list(&mm, &allocated, 0);
>   	drm_buddy_fini(&mm);
>   }
>   
> diff --git a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
> index 115ec745e502..1ad678b62c4a 100644
> --- a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
> +++ b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
> @@ -196,7 +196,7 @@ static int xe_ttm_vram_mgr_new(struct ttm_resource_manager *man,
>   	return 0;
>   
>   error_free_blocks:
> -	drm_buddy_free_list(mm, &vres->blocks);
> +	drm_buddy_free_list(mm, &vres->blocks, 0);
>   	mutex_unlock(&mgr->lock);
>   error_fini:
>   	ttm_resource_fini(man, &vres->base);
> @@ -214,7 +214,7 @@ static void xe_ttm_vram_mgr_del(struct ttm_resource_manager *man,
>   	struct drm_buddy *mm = &mgr->mm;
>   
>   	mutex_lock(&mgr->lock);
> -	drm_buddy_free_list(mm, &vres->blocks);
> +	drm_buddy_free_list(mm, &vres->blocks, 0);
>   	mgr->visible_avail += vres->used_visible_size;
>   	mutex_unlock(&mgr->lock);
>   
> diff --git a/include/drm/drm_buddy.h b/include/drm/drm_buddy.h
> index a5b39fc01003..82570f77e817 100644
> --- a/include/drm/drm_buddy.h
> +++ b/include/drm/drm_buddy.h
> @@ -25,6 +25,8 @@
>   #define DRM_BUDDY_RANGE_ALLOCATION		BIT(0)
>   #define DRM_BUDDY_TOPDOWN_ALLOCATION		BIT(1)
>   #define DRM_BUDDY_CONTIGUOUS_ALLOCATION		BIT(2)
> +#define DRM_BUDDY_CLEAR_ALLOCATION		BIT(3)
> +#define DRM_BUDDY_CLEARED			BIT(4)
>   
>   struct drm_buddy_block {
>   #define DRM_BUDDY_HEADER_OFFSET GENMASK_ULL(63, 12)
> @@ -32,8 +34,9 @@ struct drm_buddy_block {
>   #define   DRM_BUDDY_ALLOCATED	   (1 << 10)
>   #define   DRM_BUDDY_FREE	   (2 << 10)
>   #define   DRM_BUDDY_SPLIT	   (3 << 10)
> +#define DRM_BUDDY_HEADER_CLEAR  GENMASK_ULL(9, 9)
>   /* Free to be used, if needed in the future */
> -#define DRM_BUDDY_HEADER_UNUSED GENMASK_ULL(9, 6)
> +#define DRM_BUDDY_HEADER_UNUSED GENMASK_ULL(8, 6)
>   #define DRM_BUDDY_HEADER_ORDER  GENMASK_ULL(5, 0)
>   	u64 header;
>   
> @@ -86,6 +89,7 @@ struct drm_buddy {
>   	u64 chunk_size;
>   	u64 size;
>   	u64 avail;
> +	u64 clear_avail;
>   };
>   
>   static inline u64
> @@ -112,6 +116,12 @@ drm_buddy_block_is_allocated(struct drm_buddy_block *block)
>   	return drm_buddy_block_state(block) == DRM_BUDDY_ALLOCATED;
>   }
>   
> +static inline bool
> +drm_buddy_block_is_clear(struct drm_buddy_block *block)
> +{
> +	return block->header & DRM_BUDDY_HEADER_CLEAR;
> +}
> +
>   static inline bool
>   drm_buddy_block_is_free(struct drm_buddy_block *block)
>   {
> @@ -150,7 +160,9 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>   
>   void drm_buddy_free_block(struct drm_buddy *mm, struct drm_buddy_block *block);
>   
> -void drm_buddy_free_list(struct drm_buddy *mm, struct list_head *objects);
> +void drm_buddy_free_list(struct drm_buddy *mm,
> +			 struct list_head *objects,
> +			 unsigned int flags);
>   
>   void drm_buddy_print(struct drm_buddy *mm, struct drm_printer *p);
>   void drm_buddy_block_print(struct drm_buddy *mm,

Matthew Auld March 26, 2024, 6:09 p.m. UTC | #2

On 18/03/2024 21:40, Arunpravin Paneer Selvam wrote:
> - Add tracking clear page feature.
> 
> - Driver should enable the DRM_BUDDY_CLEARED flag if it
>    successfully clears the blocks in the free path. On the otherhand,
>    DRM buddy marks each block as cleared.
> 
> - Track the available cleared pages size
> 
> - If driver requests cleared memory we prefer cleared memory
>    but fallback to uncleared if we can't find the cleared blocks.
>    when driver requests uncleared memory we try to use uncleared but
>    fallback to cleared memory if necessary.
> 
> - When a block gets freed we clear it and mark the freed block as cleared,
>    when there are buddies which are cleared as well we can merge them.
>    Otherwise, we prefer to keep the blocks as separated.
> 
> - Add a function to support defragmentation.
> 
> v1:
>    - Depends on the flag check DRM_BUDDY_CLEARED, enable the block as
>      cleared. Else, reset the clear flag for each block in the list(Christian)
>    - For merging the 2 cleared blocks compare as below,
>      drm_buddy_is_clear(block) != drm_buddy_is_clear(buddy)(Christian)
>    - Defragment the memory beginning from min_order
>      till the required memory space is available.
> 
> v2: (Matthew)
>    - Add a wrapper drm_buddy_free_list_internal for the freeing of blocks
>      operation within drm buddy.
>    - Write a macro block_incompatible() to allocate the required blocks.
>    - Update the xe driver for the drm_buddy_free_list change in arguments.
>    - add a warning if the two blocks are incompatible on
>      defragmentation
>    - call full defragmentation in the fini() function
>    - place a condition to test if min_order is equal to 0
>    - replace the list with safe_reverse() variant as we might
>      remove the block from the list.
> 
> v3:
>    - fix Gitlab user reported lockup issue.
>    - Keep DRM_BUDDY_HEADER_CLEAR define sorted(Matthew)
>    - modify to pass the root order instead max_order in fini()
>      function(Matthew)
>    - change bool 1 to true(Matthew)
>    - add check if min_block_size is power of 2(Matthew)
>    - modify the min_block_size datatype to u64(Matthew)
> 
> v4:
>    - rename the function drm_buddy_defrag with __force_merge.
>    - Include __force_merge directly in drm buddy file and remove
>      the defrag use in amdgpu driver.
>    - Remove list_empty() check(Matthew)
>    - Remove unnecessary space, headers and placement of new variables(Matthew)
>    - Add a unit test case(Matthew)
> 
> Signed-off-by: Arunpravin Paneer Selvam <[e-mail]>
> Signed-off-by: Matthew Auld <[e-mail]>
> Suggested-by: Christian König <[e-mail]>
> Suggested-by: Matthew Auld <[e-mail]>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c  |   6 +-
>   drivers/gpu/drm/drm_buddy.c                   | 427 ++++++++++++++----
>   drivers/gpu/drm/i915/i915_ttm_buddy_manager.c |   6 +-
>   drivers/gpu/drm/tests/drm_buddy_test.c        |  18 +-
>   drivers/gpu/drm/xe/xe_ttm_vram_mgr.c          |   4 +-
>   include/drm/drm_buddy.h                       |  16 +-
>   6 files changed, 360 insertions(+), 117 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> index 8db880244324..c0c851409241 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> @@ -571,7 +571,7 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
>   	return 0;
>   
>   error_free_blocks:
> -	drm_buddy_free_list(mm, &vres->blocks);
> +	drm_buddy_free_list(mm, &vres->blocks, 0);
>   	mutex_unlock(&mgr->lock);
>   error_fini:
>   	ttm_resource_fini(man, &vres->base);
> @@ -604,7 +604,7 @@ static void amdgpu_vram_mgr_del(struct ttm_resource_manager *man,
>   
>   	amdgpu_vram_mgr_do_reserve(man);
>   
> -	drm_buddy_free_list(mm, &vres->blocks);
> +	drm_buddy_free_list(mm, &vres->blocks, 0);
>   	mutex_unlock(&mgr->lock);
>   
>   	atomic64_sub(vis_usage, &mgr->vis_usage);
> @@ -912,7 +912,7 @@ void amdgpu_vram_mgr_fini(struct amdgpu_device *adev)
>   		kfree(rsv);
>   
>   	list_for_each_entry_safe(rsv, temp, &mgr->reserved_pages, blocks) {
> -		drm_buddy_free_list(&mgr->mm, &rsv->allocated);
> +		drm_buddy_free_list(&mgr->mm, &rsv->allocated, 0);
>   		kfree(rsv);
>   	}
>   	if (!adev->gmc.is_app_apu)
> diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c
> index c4222b886db7..625a30a6b855 100644
> --- a/drivers/gpu/drm/drm_buddy.c
> +++ b/drivers/gpu/drm/drm_buddy.c
> @@ -38,8 +38,8 @@ static void drm_block_free(struct drm_buddy *mm,
>   	kmem_cache_free(slab_blocks, block);
>   }
>   
> -static void list_insert_sorted(struct drm_buddy *mm,
> -			       struct drm_buddy_block *block)
> +static void list_insert(struct drm_buddy *mm,
> +			struct drm_buddy_block *block)
>   {
>   	struct drm_buddy_block *node;
>   	struct list_head *head;
> @@ -57,6 +57,16 @@ static void list_insert_sorted(struct drm_buddy *mm,
>   	__list_add(&block->link, node->link.prev, &node->link);
>   }
>   
> +static void clear_reset(struct drm_buddy_block *block)
> +{
> +	block->header &= ~DRM_BUDDY_HEADER_CLEAR;
> +}
> +
> +static void mark_cleared(struct drm_buddy_block *block)
> +{
> +	block->header |= DRM_BUDDY_HEADER_CLEAR;
> +}
> +
>   static void mark_allocated(struct drm_buddy_block *block)
>   {
>   	block->header &= ~DRM_BUDDY_HEADER_STATE;
> @@ -71,7 +81,7 @@ static void mark_free(struct drm_buddy *mm,
>   	block->header &= ~DRM_BUDDY_HEADER_STATE;
>   	block->header |= DRM_BUDDY_FREE;
>   
> -	list_insert_sorted(mm, block);
> +	list_insert(mm, block);
>   }
>   
>   static void mark_split(struct drm_buddy_block *block)
> @@ -82,6 +92,114 @@ static void mark_split(struct drm_buddy_block *block)
>   	list_del(&block->link);
>   }
>   
> +static struct drm_buddy_block *
> +__get_buddy(struct drm_buddy_block *block)
> +{
> +	struct drm_buddy_block *parent;
> +
> +	parent = block->parent;
> +	if (!parent)
> +		return NULL;
> +
> +	if (parent->left == block)
> +		return parent->right;
> +
> +	return parent->left;
> +}
> +
> +static unsigned int __drm_buddy_free(struct drm_buddy *mm,
> +				     struct drm_buddy_block *block,
> +				     bool force_merge)
> +{
> +	struct drm_buddy_block *parent;
> +	unsigned int order;
> +
> +	while ((parent = block->parent)) {
> +		struct drm_buddy_block *buddy;
> +
> +		buddy = __get_buddy(block);
> +
> +		if (!drm_buddy_block_is_free(buddy))
> +			break;
> +
> +		if (!force_merge) {
> +			/**

Not really valid kernel-doc AFAIK. I think drop the extra *. Below also.

> +			 * Check the block and its buddy clear state and exit
> +			 * the loop if they both have the dissimilar state.
> +			 */
> +			if (drm_buddy_block_is_clear(block) !=
> +			    drm_buddy_block_is_clear(buddy))
> +				break;
> +
> +			if (drm_buddy_block_is_clear(block))
> +				mark_cleared(parent);
> +		}
> +
> +		list_del(&buddy->link);
> +		if (force_merge && drm_buddy_block_is_clear(buddy))
> +			mm->clear_avail -= drm_buddy_block_size(mm, buddy);
> +
> +		drm_block_free(mm, block);
> +		drm_block_free(mm, buddy);
> +
> +		block = parent;
> +	}
> +
> +	order = drm_buddy_block_order(block);
> +	mark_free(mm, block);
> +
> +	return order;
> +}
> +
> +static int __force_merge(struct drm_buddy *mm,
> +			 unsigned int min_order)
> +{
> +	unsigned int order;
> +	int i;
> +
> +	if (!min_order)
> +		return -ENOMEM;
> +
> +	if (min_order > mm->max_order)
> +		return -EINVAL;
> +
> +	for (i = min_order - 1; i >= 0; i--) {
> +		struct drm_buddy_block *block, *prev;
> +
> +		list_for_each_entry_safe_reverse(block, prev, &mm->free_list[i], link) {
> +			struct drm_buddy_block *buddy;
> +
> +			if (!block->parent)
> +				continue;
> +
> +			buddy = __get_buddy(block);
> +			if (!drm_buddy_block_is_free(buddy))
> +				continue;
> +
> +			WARN_ON(drm_buddy_block_is_clear(block) ==
> +				drm_buddy_block_is_clear(buddy));
> +
> +			/**
> +			 * If the prev block is same as buddy, don't access the
> +			 * block in the next iteration as we would free the
> +			 * buddy block as part of the free function.
> +			 */
> +			if (prev == buddy)
> +				prev = list_prev_entry(prev, link);
> +
> +			list_del(&block->link);
> +			if (drm_buddy_block_is_clear(block))
> +				mm->clear_avail -= drm_buddy_block_size(mm, block);
> +
> +			order = __drm_buddy_free(mm, block, true);
> +			if (order >= min_order)
> +				return 0;
> +		}
> +	}
> +
> +	return -ENOMEM;
> +}
> +
>   /**
>    * drm_buddy_init - init memory manager
>    *
> @@ -137,7 +255,7 @@ int drm_buddy_init(struct drm_buddy *mm, u64 size, u64 chunk_size)
>   	offset = 0;
>   	i = 0;
>   
> -	/*
> +	/**
>   	 * Split into power-of-two blocks, in case we are given a size that is
>   	 * not itself a power-of-two.
>   	 */
> @@ -186,11 +304,21 @@ EXPORT_SYMBOL(drm_buddy_init);
>    */
>   void drm_buddy_fini(struct drm_buddy *mm)
>   {
> +	u64 root_size, size;
> +	unsigned int order;
>   	int i;
>   
> +	size = mm->size;
> +
>   	for (i = 0; i < mm->n_roots; ++i) {
> +		order = ilog2(size) - ilog2(mm->chunk_size);
> +		__force_merge(mm, order);
> +
>   		WARN_ON(!drm_buddy_block_is_free(mm->roots[i]));
>   		drm_block_free(mm, mm->roots[i]);
> +
> +		root_size = mm->chunk_size << order;
> +		size -= root_size;
>   	}
>   
>   	WARN_ON(mm->avail != mm->size);
> @@ -223,26 +351,17 @@ static int split_block(struct drm_buddy *mm,
>   	mark_free(mm, block->left);
>   	mark_free(mm, block->right);
>   
> +	if (drm_buddy_block_is_clear(block)) {
> +		mark_cleared(block->left);
> +		mark_cleared(block->right);
> +		clear_reset(block);
> +	}
> +
>   	mark_split(block);
>   
>   	return 0;
>   }
>   
> -static struct drm_buddy_block *
> -__get_buddy(struct drm_buddy_block *block)
> -{
> -	struct drm_buddy_block *parent;
> -
> -	parent = block->parent;
> -	if (!parent)
> -		return NULL;
> -
> -	if (parent->left == block)
> -		return parent->right;
> -
> -	return parent->left;
> -}
> -
>   /**
>    * drm_get_buddy - get buddy address
>    *
> @@ -260,30 +379,6 @@ drm_get_buddy(struct drm_buddy_block *block)
>   }
>   EXPORT_SYMBOL(drm_get_buddy);
>   
> -static void __drm_buddy_free(struct drm_buddy *mm,
> -			     struct drm_buddy_block *block)
> -{
> -	struct drm_buddy_block *parent;
> -
> -	while ((parent = block->parent)) {
> -		struct drm_buddy_block *buddy;
> -
> -		buddy = __get_buddy(block);
> -
> -		if (!drm_buddy_block_is_free(buddy))
> -			break;
> -
> -		list_del(&buddy->link);
> -
> -		drm_block_free(mm, block);
> -		drm_block_free(mm, buddy);
> -
> -		block = parent;
> -	}
> -
> -	mark_free(mm, block);
> -}
> -
>   /**
>    * drm_buddy_free_block - free a block
>    *
> @@ -295,26 +390,59 @@ void drm_buddy_free_block(struct drm_buddy *mm,
>   {
>   	BUG_ON(!drm_buddy_block_is_allocated(block));
>   	mm->avail += drm_buddy_block_size(mm, block);
> -	__drm_buddy_free(mm, block);
> +	if (drm_buddy_block_is_clear(block))
> +		mm->clear_avail += drm_buddy_block_size(mm, block);
> +
> +	__drm_buddy_free(mm, block, false);
>   }
>   EXPORT_SYMBOL(drm_buddy_free_block);
>   
> -/**
> - * drm_buddy_free_list - free blocks
> - *
> - * @mm: DRM buddy manager
> - * @objects: input list head to free blocks
> - */
> -void drm_buddy_free_list(struct drm_buddy *mm, struct list_head *objects)
> +static void __drm_buddy_free_list(struct drm_buddy *mm,
> +				  struct list_head *objects,
> +				  bool mark_clear,
> +				  bool mark_dirty)
>   {
>   	struct drm_buddy_block *block, *on;
>   
> +	WARN_ON(mark_dirty && mark_clear);
> +
>   	list_for_each_entry_safe(block, on, objects, link) {
> +		if (mark_clear)
> +			mark_cleared(block);
> +		else if (mark_dirty)
> +			clear_reset(block);
>   		drm_buddy_free_block(mm, block);
>   		cond_resched();
>   	}
>   	INIT_LIST_HEAD(objects);
>   }
> +
> +static void drm_buddy_free_list_internal(struct drm_buddy *mm,
> +					 struct list_head *objects)
> +{
> +	/**
> +	 * Don't touch the clear/dirty bit, since allocation is still internal
> +	 * at this point. For example we might have just failed part of the
> +	 * allocation.
> +	 */
> +	__drm_buddy_free_list(mm, objects, false, false);
> +}
> +
> +/**
> + * drm_buddy_free_list - free blocks
> + *
> + * @mm: DRM buddy manager
> + * @objects: input list head to free blocks
> + * @flags: optional flags like DRM_BUDDY_CLEARED
> + */
> +void drm_buddy_free_list(struct drm_buddy *mm,
> +			 struct list_head *objects,
> +			 unsigned int flags)
> +{
> +	bool mark_clear = flags & DRM_BUDDY_CLEARED;
> +
> +	__drm_buddy_free_list(mm, objects, mark_clear, !mark_clear);
> +}
>   EXPORT_SYMBOL(drm_buddy_free_list);
>   
>   static inline bool overlaps(u64 s1, u64 e1, u64 s2, u64 e2)
> @@ -327,10 +455,19 @@ static inline bool contains(u64 s1, u64 e1, u64 s2, u64 e2)
>   	return s1 <= s2 && e1 >= e2;
>   }
>   
> +static bool block_incompatible(struct drm_buddy_block *block, unsigned int flags)
> +{
> +	bool needs_clear = flags & DRM_BUDDY_CLEAR_ALLOCATION;
> +
> +	return needs_clear != drm_buddy_block_is_clear(block);
> +}
> +
>   static struct drm_buddy_block *
> -alloc_range_bias(struct drm_buddy *mm,
> -		 u64 start, u64 end,
> -		 unsigned int order)
> +__alloc_range_bias(struct drm_buddy *mm,
> +		   u64 start, u64 end,
> +		   unsigned int order,
> +		   unsigned long flags,
> +		   bool fallback)
>   {
>   	struct drm_buddy_block *block;
>   	struct drm_buddy_block *buddy;
> @@ -369,7 +506,10 @@ alloc_range_bias(struct drm_buddy *mm,
>   
>   		if (contains(start, end, block_start, block_end) &&
>   		    order == drm_buddy_block_order(block)) {
> -			/*
> +			if (!fallback && block_incompatible(block, flags))
> +				continue;
> +
> +			/**
>   			 * Find the free block within the range.
>   			 */
>   			if (drm_buddy_block_is_free(block))
> @@ -391,7 +531,7 @@ alloc_range_bias(struct drm_buddy *mm,
>   	return ERR_PTR(-ENOSPC);
>   
>   err_undo:
> -	/*
> +	/**
>   	 * We really don't want to leave around a bunch of split blocks, since
>   	 * bigger is better, so make sure we merge everything back before we
>   	 * free the allocated blocks.
> @@ -400,30 +540,57 @@ alloc_range_bias(struct drm_buddy *mm,
>   	if (buddy &&
>   	    (drm_buddy_block_is_free(block) &&
>   	     drm_buddy_block_is_free(buddy)))
> -		__drm_buddy_free(mm, block);
> +		__drm_buddy_free(mm, block, false);
>   	return ERR_PTR(err);
>   }
>   
>   static struct drm_buddy_block *
> -get_maxblock(struct drm_buddy *mm, unsigned int order)
> +__drm_buddy_alloc_range_bias(struct drm_buddy *mm,
> +			     u64 start, u64 end,
> +			     unsigned int order,
> +			     unsigned long flags)
> +{
> +	struct drm_buddy_block *block;
> +	bool fallback = false;
> +
> +	block = __alloc_range_bias(mm, start, end, order,
> +				   flags, fallback);
> +	if (IS_ERR(block) && mm->clear_avail)
> +		return __alloc_range_bias(mm, start, end, order,
> +					  flags, !fallback);
> +
> +	return block;
> +}
> +
> +static struct drm_buddy_block *
> +get_maxblock(struct drm_buddy *mm, unsigned int order,
> +	     unsigned long flags)
>   {
> -	struct drm_buddy_block *max_block = NULL, *node;
> +	struct drm_buddy_block *max_block = NULL, *block = NULL;
>   	unsigned int i;
>   
>   	for (i = order; i <= mm->max_order; ++i) {
> -		if (!list_empty(&mm->free_list[i])) {
> -			node = list_last_entry(&mm->free_list[i],
> -					       struct drm_buddy_block,
> -					       link);
> -			if (!max_block) {
> -				max_block = node;
> +		struct drm_buddy_block *tmp_block;
> +
> +		list_for_each_entry_reverse(tmp_block, &mm->free_list[i], link) {
> +			if (block_incompatible(tmp_block, flags))
>   				continue;
> -			}
>   
> -			if (drm_buddy_block_offset(node) >
> -			    drm_buddy_block_offset(max_block)) {
> -				max_block = node;
> -			}
> +			block = tmp_block;
> +			break;
> +		}
> +
> +		if (!block)
> +			continue;
> +
> +		if (!max_block) {
> +			max_block = block;
> +			continue;
> +		}
> +
> +		if (drm_buddy_block_offset(block) >
> +		    drm_buddy_block_offset(max_block)) {
> +			max_block = block;
>   		}
>   	}
>   
> @@ -440,11 +607,29 @@ alloc_from_freelist(struct drm_buddy *mm,
>   	int err;
>   
>   	if (flags & DRM_BUDDY_TOPDOWN_ALLOCATION) {
> -		block = get_maxblock(mm, order);
> +		block = get_maxblock(mm, order, flags);
>   		if (block)
>   			/* Store the obtained block order */
>   			tmp = drm_buddy_block_order(block);
>   	} else {
> +		for (tmp = order; tmp <= mm->max_order; ++tmp) {
> +			struct drm_buddy_block *tmp_block;
> +
> +			list_for_each_entry_reverse(tmp_block, &mm->free_list[tmp], link) {
> +				if (block_incompatible(tmp_block, flags))
> +					continue;
> +
> +				block = tmp_block;
> +				break;
> +			}
> +
> +			if (block)
> +				break;
> +		}
> +	}
> +
> +	if (!block) {
> +		/* Fallback method */
>   		for (tmp = order; tmp <= mm->max_order; ++tmp) {
>   			if (!list_empty(&mm->free_list[tmp])) {
>   				block = list_last_entry(&mm->free_list[tmp],
> @@ -454,10 +639,10 @@ alloc_from_freelist(struct drm_buddy *mm,
>   					break;
>   			}
>   		}
> -	}
>   
> -	if (!block)
> -		return ERR_PTR(-ENOSPC);
> +		if (!block)
> +			return ERR_PTR(-ENOSPC);
> +	}
>   
>   	BUG_ON(!drm_buddy_block_is_free(block));
>   
> @@ -473,7 +658,7 @@ alloc_from_freelist(struct drm_buddy *mm,
>   
>   err_undo:
>   	if (tmp != order)
> -		__drm_buddy_free(mm, block);
> +		__drm_buddy_free(mm, block, false);
>   	return ERR_PTR(err);
>   }
>   
> @@ -524,6 +709,8 @@ static int __alloc_range(struct drm_buddy *mm,
>   			mark_allocated(block);
>   			total_allocated += drm_buddy_block_size(mm, block);
>   			mm->avail -= drm_buddy_block_size(mm, block);
> +			if (drm_buddy_block_is_clear(block))
> +				mm->clear_avail -= drm_buddy_block_size(mm, block);
>   			list_add_tail(&block->link, &allocated);
>   			continue;
>   		}
> @@ -548,7 +735,7 @@ static int __alloc_range(struct drm_buddy *mm,
>   	return 0;
>   
>   err_undo:
> -	/*
> +	/**
>   	 * We really don't want to leave around a bunch of split blocks, since
>   	 * bigger is better, so make sure we merge everything back before we
>   	 * free the allocated blocks.
> @@ -557,14 +744,14 @@ static int __alloc_range(struct drm_buddy *mm,
>   	if (buddy &&
>   	    (drm_buddy_block_is_free(block) &&
>   	     drm_buddy_block_is_free(buddy)))
> -		__drm_buddy_free(mm, block);
> +		__drm_buddy_free(mm, block, false);
>   
>   err_free:
>   	if (err == -ENOSPC && total_allocated_on_err) {
>   		list_splice_tail(&allocated, blocks);
>   		*total_allocated_on_err = total_allocated;
>   	} else {
> -		drm_buddy_free_list(mm, &allocated);
> +		drm_buddy_free_list_internal(mm, &allocated);
>   	}
>   
>   	return err;
> @@ -630,11 +817,11 @@ static int __alloc_contig_try_harder(struct drm_buddy *mm,
>   			list_splice(&blocks_lhs, blocks);
>   			return 0;
>   		} else if (err != -ENOSPC) {
> -			drm_buddy_free_list(mm, blocks);
> +			drm_buddy_free_list_internal(mm, blocks);
>   			return err;
>   		}
>   		/* Free blocks for the next iteration */
> -		drm_buddy_free_list(mm, blocks);
> +		drm_buddy_free_list_internal(mm, blocks);
>   	}
>   
>   	return -ENOSPC;
> @@ -690,6 +877,8 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>   	list_del(&block->link);
>   	mark_free(mm, block);
>   	mm->avail += drm_buddy_block_size(mm, block);
> +	if (drm_buddy_block_is_clear(block))
> +		mm->clear_avail += drm_buddy_block_size(mm, block);
>   
>   	/* Prevent recursively freeing this node */
>   	parent = block->parent;
> @@ -701,6 +890,8 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>   	if (err) {
>   		mark_allocated(block);
>   		mm->avail -= drm_buddy_block_size(mm, block);
> +		if (drm_buddy_block_is_clear(block))
> +			mm->clear_avail -= drm_buddy_block_size(mm, block);
>   		list_add(&block->link, blocks);
>   	}
>   
> @@ -709,13 +900,28 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>   }
>   EXPORT_SYMBOL(drm_buddy_block_trim);
>   
> +static struct drm_buddy_block *
> +__drm_buddy_alloc_blocks(struct drm_buddy *mm,
> +			 u64 start, u64 end,
> +			 unsigned int order,
> +			 unsigned long flags)
> +{
> +	if (flags & DRM_BUDDY_RANGE_ALLOCATION)
> +		/* Allocate traversing within the range */
> +		return  __drm_buddy_alloc_range_bias(mm, start, end,
> +						     order, flags);
> +	else
> +		/* Allocate from freelist */
> +		return alloc_from_freelist(mm, order, flags);
> +}
> +
>   /**
>    * drm_buddy_alloc_blocks - allocate power-of-two blocks
>    *
>    * @mm: DRM buddy manager to allocate from
>    * @start: start of the allowed range for this block
>    * @end: end of the allowed range for this block
> - * @size: size of the allocation
> + * @size: size of the allocation in bytes
>    * @min_block_size: alignment of the allocation
>    * @blocks: output list head to add allocated blocks
>    * @flags: DRM_BUDDY_*_ALLOCATION flags
> @@ -761,8 +967,18 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>   		return -EINVAL;
>   
>   	/* Actual range allocation */
> -	if (start + size == end)
> -		return __drm_buddy_alloc_range(mm, start, size, NULL, blocks);
> +	if (start + size == end) {
> +		err =  __drm_buddy_alloc_range(mm, start, size, NULL, blocks);
> +		if (err) {
> +			order = ilog2(size) - ilog2(mm->chunk_size);
> +			if (mm->clear_avail && !__force_merge(mm, order))
> +				return __drm_buddy_alloc_range(mm, start, size, NULL, blocks);

That seems strange at a glance. With an actual range allocation like 
with intitial fb or whatever it should just find all overlapping pages, 
splitting down where needed on the edges. Not sure why force_merge would 
factor in here?

> +
> +			return err;
> +		}
> +
> +		return err;
> +	}
>   
>   	original_size = size;
>   	original_min_size = min_block_size;
> @@ -786,23 +1002,34 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>   		BUG_ON(order < min_order);
>   
>   		do {
> -			if (flags & DRM_BUDDY_RANGE_ALLOCATION)
> -				/* Allocate traversing within the range */
> -				block = alloc_range_bias(mm, start, end, order);
> -			else
> -				/* Allocate from freelist */
> -				block = alloc_from_freelist(mm, order, flags);
> -
> +			block = __drm_buddy_alloc_blocks(mm, start,
> +							 end,
> +							 order,
> +							 flags);
>   			if (!IS_ERR(block))
>   				break;
>   
>   			if (order-- == min_order) {
> +				/**
> +				 * Try allocation through force merge method
> +				 */
> +				if (mm->clear_avail && !__force_merge(mm, min_order)) {
> +					block = __drm_buddy_alloc_blocks(mm, start,
> +									 end,
> +									 min_order,
> +									 flags);
> +					if (!IS_ERR(block)) {
> +						order = min_order;
> +						break;
> +					}
> +				}
> +
> +				/**
> +				 * Try contiguous block allocation through
> +				 * try harder method.
> +				 */
>   				if (flags & DRM_BUDDY_CONTIGUOUS_ALLOCATION &&
>   				    !(flags & DRM_BUDDY_RANGE_ALLOCATION))
> -					/*
> -					 * Try contiguous block allocation through
> -					 * try harder method
> -					 */
>   					return __alloc_contig_try_harder(mm,
>   									 original_size,
>   									 original_min_size,
> @@ -814,6 +1041,8 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>   
>   		mark_allocated(block);
>   		mm->avail -= drm_buddy_block_size(mm, block);
> +		if (drm_buddy_block_is_clear(block))
> +			mm->clear_avail -= drm_buddy_block_size(mm, block);
>   		kmemleak_update_trace(block);
>   		list_add_tail(&block->link, &allocated);
>   
> @@ -823,7 +1052,9 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>   			break;
>   	} while (1);
>   
> -	/* Trim the allocated block to the required size */
> +	/**
> +	 * Trim the allocated block to the required size
> +	 */
>   	if (original_size != size) {
>   		struct list_head *trim_list;
>   		LIST_HEAD(temp);
> @@ -852,7 +1083,7 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>   	return 0;
>   
>   err_free:
> -	drm_buddy_free_list(mm, &allocated);
> +	drm_buddy_free_list_internal(mm, &allocated);
>   	return err;
>   }
>   EXPORT_SYMBOL(drm_buddy_alloc_blocks);
> @@ -885,8 +1116,8 @@ void drm_buddy_print(struct drm_buddy *mm, struct drm_printer *p)
>   {
>   	int order;
>   
> -	drm_printf(p, "chunk_size: %lluKiB, total: %lluMiB, free: %lluMiB\n",
> -		   mm->chunk_size >> 10, mm->size >> 20, mm->avail >> 20);
> +	drm_printf(p, "chunk_size: %lluKiB, total: %lluMiB, free: %lluMiB, clear_free: %lluMiB\n",
> +		   mm->chunk_size >> 10, mm->size >> 20, mm->avail >> 20, mm->clear_avail >> 20);
>   
>   	for (order = mm->max_order; order >= 0; order--) {
>   		struct drm_buddy_block *block;
> diff --git a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
> index 0d735d5c2b35..942345548bc3 100644
> --- a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
> +++ b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
> @@ -126,7 +126,7 @@ static int i915_ttm_buddy_man_alloc(struct ttm_resource_manager *man,
>   	return 0;
>   
>   err_free_blocks:
> -	drm_buddy_free_list(mm, &bman_res->blocks);
> +	drm_buddy_free_list(mm, &bman_res->blocks, 0);
>   	mutex_unlock(&bman->lock);
>   err_free_res:
>   	ttm_resource_fini(man, &bman_res->base);
> @@ -141,7 +141,7 @@ static void i915_ttm_buddy_man_free(struct ttm_resource_manager *man,
>   	struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
>   
>   	mutex_lock(&bman->lock);
> -	drm_buddy_free_list(&bman->mm, &bman_res->blocks);
> +	drm_buddy_free_list(&bman->mm, &bman_res->blocks, 0);
>   	bman->visible_avail += bman_res->used_visible_size;
>   	mutex_unlock(&bman->lock);
>   
> @@ -345,7 +345,7 @@ int i915_ttm_buddy_man_fini(struct ttm_device *bdev, unsigned int type)
>   	ttm_set_driver_manager(bdev, type, NULL);
>   
>   	mutex_lock(&bman->lock);
> -	drm_buddy_free_list(mm, &bman->reserved);
> +	drm_buddy_free_list(mm, &bman->reserved, 0);
>   	drm_buddy_fini(mm);
>   	bman->visible_avail += bman->visible_reserved;
>   	WARN_ON_ONCE(bman->visible_avail != bman->visible_size);
> diff --git a/drivers/gpu/drm/tests/drm_buddy_test.c b/drivers/gpu/drm/tests/drm_buddy_test.c
> index 2f32fb2f12e7..454ad9952f56 100644
> --- a/drivers/gpu/drm/tests/drm_buddy_test.c
> +++ b/drivers/gpu/drm/tests/drm_buddy_test.c
> @@ -64,7 +64,7 @@ static void drm_test_buddy_alloc_contiguous(struct kunit *test)
>   							   DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>   			       "buddy_alloc didn't error size=%u\n", 3 * ps);
>   
> -	drm_buddy_free_list(&mm, &middle);
> +	drm_buddy_free_list(&mm, &middle, 0);
>   	KUNIT_ASSERT_TRUE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
>   							   3 * ps, ps, &allocated,
>   							   DRM_BUDDY_CONTIGUOUS_ALLOCATION),
> @@ -74,7 +74,7 @@ static void drm_test_buddy_alloc_contiguous(struct kunit *test)
>   							   DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>   			       "buddy_alloc didn't error size=%u\n", 2 * ps);
>   
> -	drm_buddy_free_list(&mm, &right);
> +	drm_buddy_free_list(&mm, &right, 0);
>   	KUNIT_ASSERT_TRUE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
>   							   3 * ps, ps, &allocated,
>   							   DRM_BUDDY_CONTIGUOUS_ALLOCATION),
> @@ -89,7 +89,7 @@ static void drm_test_buddy_alloc_contiguous(struct kunit *test)
>   							    DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>   			       "buddy_alloc hit an error size=%u\n", 2 * ps);
>   
> -	drm_buddy_free_list(&mm, &left);
> +	drm_buddy_free_list(&mm, &left, 0);
>   	KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
>   							    3 * ps, ps, &allocated,
>   							    DRM_BUDDY_CONTIGUOUS_ALLOCATION),
> @@ -101,7 +101,7 @@ static void drm_test_buddy_alloc_contiguous(struct kunit *test)
>   
>   	KUNIT_ASSERT_EQ(test, total, ps * 2 + ps * 3);
>   
> -	drm_buddy_free_list(&mm, &allocated);
> +	drm_buddy_free_list(&mm, &allocated, 0);
>   	drm_buddy_fini(&mm);
>   }
>   
> @@ -170,7 +170,7 @@ static void drm_test_buddy_alloc_pathological(struct kunit *test)
>   							  top, max_order);
>   	}
>   
> -	drm_buddy_free_list(&mm, &holes);
> +	drm_buddy_free_list(&mm, &holes, 0);
>   
>   	/* Nothing larger than blocks of chunk_size now available */
>   	for (order = 1; order <= max_order; order++) {
> @@ -182,7 +182,7 @@ static void drm_test_buddy_alloc_pathological(struct kunit *test)
>   	}
>   
>   	list_splice_tail(&holes, &blocks);
> -	drm_buddy_free_list(&mm, &blocks);
> +	drm_buddy_free_list(&mm, &blocks, 0);
>   	drm_buddy_fini(&mm);
>   }
>   
> @@ -277,7 +277,7 @@ static void drm_test_buddy_alloc_pessimistic(struct kunit *test)
>   
>   	list_del(&block->link);
>   	drm_buddy_free_block(&mm, block);
> -	drm_buddy_free_list(&mm, &blocks);
> +	drm_buddy_free_list(&mm, &blocks, 0);
>   	drm_buddy_fini(&mm);
>   }
>   
> @@ -323,7 +323,7 @@ static void drm_test_buddy_alloc_optimistic(struct kunit *test)
>   							   size, size, &tmp, flags),
>   						  "buddy_alloc unexpectedly succeeded, it should be full!");
>   
> -	drm_buddy_free_list(&mm, &blocks);
> +	drm_buddy_free_list(&mm, &blocks, 0);
>   	drm_buddy_fini(&mm);
>   }
>   
> @@ -358,7 +358,7 @@ static void drm_test_buddy_alloc_limit(struct kunit *test)
>   						drm_buddy_block_size(&mm, block),
>   						BIT_ULL(mm.max_order) * PAGE_SIZE);
>   
> -	drm_buddy_free_list(&mm, &allocated);
> +	drm_buddy_free_list(&mm, &allocated, 0);
>   	drm_buddy_fini(&mm);
>   }
>   
> diff --git a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
> index 115ec745e502..1ad678b62c4a 100644
> --- a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
> +++ b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
> @@ -196,7 +196,7 @@ static int xe_ttm_vram_mgr_new(struct ttm_resource_manager *man,
>   	return 0;
>   
>   error_free_blocks:
> -	drm_buddy_free_list(mm, &vres->blocks);
> +	drm_buddy_free_list(mm, &vres->blocks, 0);
>   	mutex_unlock(&mgr->lock);
>   error_fini:
>   	ttm_resource_fini(man, &vres->base);
> @@ -214,7 +214,7 @@ static void xe_ttm_vram_mgr_del(struct ttm_resource_manager *man,
>   	struct drm_buddy *mm = &mgr->mm;
>   
>   	mutex_lock(&mgr->lock);
> -	drm_buddy_free_list(mm, &vres->blocks);
> +	drm_buddy_free_list(mm, &vres->blocks, 0);
>   	mgr->visible_avail += vres->used_visible_size;
>   	mutex_unlock(&mgr->lock);
>   
> diff --git a/include/drm/drm_buddy.h b/include/drm/drm_buddy.h
> index a5b39fc01003..82570f77e817 100644
> --- a/include/drm/drm_buddy.h
> +++ b/include/drm/drm_buddy.h
> @@ -25,6 +25,8 @@
>   #define DRM_BUDDY_RANGE_ALLOCATION		BIT(0)
>   #define DRM_BUDDY_TOPDOWN_ALLOCATION		BIT(1)
>   #define DRM_BUDDY_CONTIGUOUS_ALLOCATION		BIT(2)
> +#define DRM_BUDDY_CLEAR_ALLOCATION		BIT(3)
> +#define DRM_BUDDY_CLEARED			BIT(4)
>   
>   struct drm_buddy_block {
>   #define DRM_BUDDY_HEADER_OFFSET GENMASK_ULL(63, 12)
> @@ -32,8 +34,9 @@ struct drm_buddy_block {
>   #define   DRM_BUDDY_ALLOCATED	   (1 << 10)
>   #define   DRM_BUDDY_FREE	   (2 << 10)
>   #define   DRM_BUDDY_SPLIT	   (3 << 10)
> +#define DRM_BUDDY_HEADER_CLEAR  GENMASK_ULL(9, 9)
>   /* Free to be used, if needed in the future */
> -#define DRM_BUDDY_HEADER_UNUSED GENMASK_ULL(9, 6)
> +#define DRM_BUDDY_HEADER_UNUSED GENMASK_ULL(8, 6)
>   #define DRM_BUDDY_HEADER_ORDER  GENMASK_ULL(5, 0)
>   	u64 header;
>   
> @@ -86,6 +89,7 @@ struct drm_buddy {
>   	u64 chunk_size;
>   	u64 size;
>   	u64 avail;
> +	u64 clear_avail;
>   };
>   
>   static inline u64
> @@ -112,6 +116,12 @@ drm_buddy_block_is_allocated(struct drm_buddy_block *block)
>   	return drm_buddy_block_state(block) == DRM_BUDDY_ALLOCATED;
>   }
>   
> +static inline bool
> +drm_buddy_block_is_clear(struct drm_buddy_block *block)
> +{
> +	return block->header & DRM_BUDDY_HEADER_CLEAR;
> +}
> +
>   static inline bool
>   drm_buddy_block_is_free(struct drm_buddy_block *block)
>   {
> @@ -150,7 +160,9 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>   
>   void drm_buddy_free_block(struct drm_buddy *mm, struct drm_buddy_block *block);
>   
> -void drm_buddy_free_list(struct drm_buddy *mm, struct list_head *objects);
> +void drm_buddy_free_list(struct drm_buddy *mm,
> +			 struct list_head *objects,
> +			 unsigned int flags);
>   
>   void drm_buddy_print(struct drm_buddy *mm, struct drm_printer *p);
>   void drm_buddy_block_print(struct drm_buddy *mm,

Paneer Selvam, Arunpravin March 28, 2024, 4:07 p.m. UTC | #3

Hi Matthew,

On 3/26/2024 11:39 PM, Matthew Auld wrote:
> On 18/03/2024 21:40, Arunpravin Paneer Selvam wrote:
>> - Add tracking clear page feature.
>>
>> - Driver should enable the DRM_BUDDY_CLEARED flag if it
>>    successfully clears the blocks in the free path. On the otherhand,
>>    DRM buddy marks each block as cleared.
>>
>> - Track the available cleared pages size
>>
>> - If driver requests cleared memory we prefer cleared memory
>>    but fallback to uncleared if we can't find the cleared blocks.
>>    when driver requests uncleared memory we try to use uncleared but
>>    fallback to cleared memory if necessary.
>>
>> - When a block gets freed we clear it and mark the freed block as 
>> cleared,
>>    when there are buddies which are cleared as well we can merge them.
>>    Otherwise, we prefer to keep the blocks as separated.
>>
>> - Add a function to support defragmentation.
>>
>> v1:
>>    - Depends on the flag check DRM_BUDDY_CLEARED, enable the block as
>>      cleared. Else, reset the clear flag for each block in the 
>> list(Christian)
>>    - For merging the 2 cleared blocks compare as below,
>>      drm_buddy_is_clear(block) != drm_buddy_is_clear(buddy)(Christian)
>>    - Defragment the memory beginning from min_order
>>      till the required memory space is available.
>>
>> v2: (Matthew)
>>    - Add a wrapper drm_buddy_free_list_internal for the freeing of 
>> blocks
>>      operation within drm buddy.
>>    - Write a macro block_incompatible() to allocate the required blocks.
>>    - Update the xe driver for the drm_buddy_free_list change in 
>> arguments.
>>    - add a warning if the two blocks are incompatible on
>>      defragmentation
>>    - call full defragmentation in the fini() function
>>    - place a condition to test if min_order is equal to 0
>>    - replace the list with safe_reverse() variant as we might
>>      remove the block from the list.
>>
>> v3:
>>    - fix Gitlab user reported lockup issue.
>>    - Keep DRM_BUDDY_HEADER_CLEAR define sorted(Matthew)
>>    - modify to pass the root order instead max_order in fini()
>>      function(Matthew)
>>    - change bool 1 to true(Matthew)
>>    - add check if min_block_size is power of 2(Matthew)
>>    - modify the min_block_size datatype to u64(Matthew)
>>
>> v4:
>>    - rename the function drm_buddy_defrag with __force_merge.
>>    - Include __force_merge directly in drm buddy file and remove
>>      the defrag use in amdgpu driver.
>>    - Remove list_empty() check(Matthew)
>>    - Remove unnecessary space, headers and placement of new 
>> variables(Matthew)
>>    - Add a unit test case(Matthew)
>>
>> Signed-off-by: Arunpravin Paneer Selvam 
>> <[e-mail]>
>> Signed-off-by: Matthew Auld <[e-mail]>
>> Suggested-by: Christian König <[e-mail]>
>> Suggested-by: Matthew Auld <[e-mail]>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c  |   6 +-
>>   drivers/gpu/drm/drm_buddy.c                   | 427 ++++++++++++++----
>>   drivers/gpu/drm/i915/i915_ttm_buddy_manager.c |   6 +-
>>   drivers/gpu/drm/tests/drm_buddy_test.c        |  18 +-
>>   drivers/gpu/drm/xe/xe_ttm_vram_mgr.c          |   4 +-
>>   include/drm/drm_buddy.h                       |  16 +-
>>   6 files changed, 360 insertions(+), 117 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>> index 8db880244324..c0c851409241 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>> @@ -571,7 +571,7 @@ static int amdgpu_vram_mgr_new(struct 
>> ttm_resource_manager *man,
>>       return 0;
>>     error_free_blocks:
>> -    drm_buddy_free_list(mm, &vres->blocks);
>> +    drm_buddy_free_list(mm, &vres->blocks, 0);
>>       mutex_unlock(&mgr->lock);
>>   error_fini:
>>       ttm_resource_fini(man, &vres->base);
>> @@ -604,7 +604,7 @@ static void amdgpu_vram_mgr_del(struct 
>> ttm_resource_manager *man,
>>         amdgpu_vram_mgr_do_reserve(man);
>>   -    drm_buddy_free_list(mm, &vres->blocks);
>> +    drm_buddy_free_list(mm, &vres->blocks, 0);
>>       mutex_unlock(&mgr->lock);
>>         atomic64_sub(vis_usage, &mgr->vis_usage);
>> @@ -912,7 +912,7 @@ void amdgpu_vram_mgr_fini(struct amdgpu_device 
>> *adev)
>>           kfree(rsv);
>>         list_for_each_entry_safe(rsv, temp, &mgr->reserved_pages, 
>> blocks) {
>> -        drm_buddy_free_list(&mgr->mm, &rsv->allocated);
>> +        drm_buddy_free_list(&mgr->mm, &rsv->allocated, 0);
>>           kfree(rsv);
>>       }
>>       if (!adev->gmc.is_app_apu)
>> diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c
>> index c4222b886db7..625a30a6b855 100644
>> --- a/drivers/gpu/drm/drm_buddy.c
>> +++ b/drivers/gpu/drm/drm_buddy.c
>> @@ -38,8 +38,8 @@ static void drm_block_free(struct drm_buddy *mm,
>>       kmem_cache_free(slab_blocks, block);
>>   }
>>   -static void list_insert_sorted(struct drm_buddy *mm,
>> -                   struct drm_buddy_block *block)
>> +static void list_insert(struct drm_buddy *mm,
>> +            struct drm_buddy_block *block)
>>   {
>>       struct drm_buddy_block *node;
>>       struct list_head *head;
>> @@ -57,6 +57,16 @@ static void list_insert_sorted(struct drm_buddy *mm,
>>       __list_add(&block->link, node->link.prev, &node->link);
>>   }
>>   +static void clear_reset(struct drm_buddy_block *block)
>> +{
>> +    block->header &= ~DRM_BUDDY_HEADER_CLEAR;
>> +}
>> +
>> +static void mark_cleared(struct drm_buddy_block *block)
>> +{
>> +    block->header |= DRM_BUDDY_HEADER_CLEAR;
>> +}
>> +
>>   static void mark_allocated(struct drm_buddy_block *block)
>>   {
>>       block->header &= ~DRM_BUDDY_HEADER_STATE;
>> @@ -71,7 +81,7 @@ static void mark_free(struct drm_buddy *mm,
>>       block->header &= ~DRM_BUDDY_HEADER_STATE;
>>       block->header |= DRM_BUDDY_FREE;
>>   -    list_insert_sorted(mm, block);
>> +    list_insert(mm, block);
>>   }
>>     static void mark_split(struct drm_buddy_block *block)
>> @@ -82,6 +92,114 @@ static void mark_split(struct drm_buddy_block 
>> *block)
>>       list_del(&block->link);
>>   }
>>   +static struct drm_buddy_block *
>> +__get_buddy(struct drm_buddy_block *block)
>> +{
>> +    struct drm_buddy_block *parent;
>> +
>> +    parent = block->parent;
>> +    if (!parent)
>> +        return NULL;
>> +
>> +    if (parent->left == block)
>> +        return parent->right;
>> +
>> +    return parent->left;
>> +}
>> +
>> +static unsigned int __drm_buddy_free(struct drm_buddy *mm,
>> +                     struct drm_buddy_block *block,
>> +                     bool force_merge)
>> +{
>> +    struct drm_buddy_block *parent;
>> +    unsigned int order;
>> +
>> +    while ((parent = block->parent)) {
>> +        struct drm_buddy_block *buddy;
>> +
>> +        buddy = __get_buddy(block);
>> +
>> +        if (!drm_buddy_block_is_free(buddy))
>> +            break;
>> +
>> +        if (!force_merge) {
>> +            /**
>
> Not really valid kernel-doc AFAIK. I think drop the extra *. Below also.
>
>> +             * Check the block and its buddy clear state and exit
>> +             * the loop if they both have the dissimilar state.
>> +             */
>> +            if (drm_buddy_block_is_clear(block) !=
>> +                drm_buddy_block_is_clear(buddy))
>> +                break;
>> +
>> +            if (drm_buddy_block_is_clear(block))
>> +                mark_cleared(parent);
>> +        }
>> +
>> +        list_del(&buddy->link);
>> +        if (force_merge && drm_buddy_block_is_clear(buddy))
>> +            mm->clear_avail -= drm_buddy_block_size(mm, buddy);
>> +
>> +        drm_block_free(mm, block);
>> +        drm_block_free(mm, buddy);
>> +
>> +        block = parent;
>> +    }
>> +
>> +    order = drm_buddy_block_order(block);
>> +    mark_free(mm, block);
>> +
>> +    return order;
>> +}
>> +
>> +static int __force_merge(struct drm_buddy *mm,
>> +             unsigned int min_order)
>> +{
>> +    unsigned int order;
>> +    int i;
>> +
>> +    if (!min_order)
>> +        return -ENOMEM;
>> +
>> +    if (min_order > mm->max_order)
>> +        return -EINVAL;
>> +
>> +    for (i = min_order - 1; i >= 0; i--) {
>> +        struct drm_buddy_block *block, *prev;
>> +
>> +        list_for_each_entry_safe_reverse(block, prev, 
>> &mm->free_list[i], link) {
>> +            struct drm_buddy_block *buddy;
>> +
>> +            if (!block->parent)
>> +                continue;
>> +
>> +            buddy = __get_buddy(block);
>> +            if (!drm_buddy_block_is_free(buddy))
>> +                continue;
>> +
>> +            WARN_ON(drm_buddy_block_is_clear(block) ==
>> +                drm_buddy_block_is_clear(buddy));
>> +
>> +            /**
>> +             * If the prev block is same as buddy, don't access the
>> +             * block in the next iteration as we would free the
>> +             * buddy block as part of the free function.
>> +             */
>> +            if (prev == buddy)
>> +                prev = list_prev_entry(prev, link);
>> +
>> +            list_del(&block->link);
>> +            if (drm_buddy_block_is_clear(block))
>> +                mm->clear_avail -= drm_buddy_block_size(mm, block);
>> +
>> +            order = __drm_buddy_free(mm, block, true);
>> +            if (order >= min_order)
>> +                return 0;
>> +        }
>> +    }
>> +
>> +    return -ENOMEM;
>> +}
>> +
>>   /**
>>    * drm_buddy_init - init memory manager
>>    *
>> @@ -137,7 +255,7 @@ int drm_buddy_init(struct drm_buddy *mm, u64 
>> size, u64 chunk_size)
>>       offset = 0;
>>       i = 0;
>>   -    /*
>> +    /**
>>        * Split into power-of-two blocks, in case we are given a size 
>> that is
>>        * not itself a power-of-two.
>>        */
>> @@ -186,11 +304,21 @@ EXPORT_SYMBOL(drm_buddy_init);
>>    */
>>   void drm_buddy_fini(struct drm_buddy *mm)
>>   {
>> +    u64 root_size, size;
>> +    unsigned int order;
>>       int i;
>>   +    size = mm->size;
>> +
>>       for (i = 0; i < mm->n_roots; ++i) {
>> +        order = ilog2(size) - ilog2(mm->chunk_size);
>> +        __force_merge(mm, order);
>> +
>>           WARN_ON(!drm_buddy_block_is_free(mm->roots[i]));
>>           drm_block_free(mm, mm->roots[i]);
>> +
>> +        root_size = mm->chunk_size << order;
>> +        size -= root_size;
>>       }
>>         WARN_ON(mm->avail != mm->size);
>> @@ -223,26 +351,17 @@ static int split_block(struct drm_buddy *mm,
>>       mark_free(mm, block->left);
>>       mark_free(mm, block->right);
>>   +    if (drm_buddy_block_is_clear(block)) {
>> +        mark_cleared(block->left);
>> +        mark_cleared(block->right);
>> +        clear_reset(block);
>> +    }
>> +
>>       mark_split(block);
>>         return 0;
>>   }
>>   -static struct drm_buddy_block *
>> -__get_buddy(struct drm_buddy_block *block)
>> -{
>> -    struct drm_buddy_block *parent;
>> -
>> -    parent = block->parent;
>> -    if (!parent)
>> -        return NULL;
>> -
>> -    if (parent->left == block)
>> -        return parent->right;
>> -
>> -    return parent->left;
>> -}
>> -
>>   /**
>>    * drm_get_buddy - get buddy address
>>    *
>> @@ -260,30 +379,6 @@ drm_get_buddy(struct drm_buddy_block *block)
>>   }
>>   EXPORT_SYMBOL(drm_get_buddy);
>>   -static void __drm_buddy_free(struct drm_buddy *mm,
>> -                 struct drm_buddy_block *block)
>> -{
>> -    struct drm_buddy_block *parent;
>> -
>> -    while ((parent = block->parent)) {
>> -        struct drm_buddy_block *buddy;
>> -
>> -        buddy = __get_buddy(block);
>> -
>> -        if (!drm_buddy_block_is_free(buddy))
>> -            break;
>> -
>> -        list_del(&buddy->link);
>> -
>> -        drm_block_free(mm, block);
>> -        drm_block_free(mm, buddy);
>> -
>> -        block = parent;
>> -    }
>> -
>> -    mark_free(mm, block);
>> -}
>> -
>>   /**
>>    * drm_buddy_free_block - free a block
>>    *
>> @@ -295,26 +390,59 @@ void drm_buddy_free_block(struct drm_buddy *mm,
>>   {
>>       BUG_ON(!drm_buddy_block_is_allocated(block));
>>       mm->avail += drm_buddy_block_size(mm, block);
>> -    __drm_buddy_free(mm, block);
>> +    if (drm_buddy_block_is_clear(block))
>> +        mm->clear_avail += drm_buddy_block_size(mm, block);
>> +
>> +    __drm_buddy_free(mm, block, false);
>>   }
>>   EXPORT_SYMBOL(drm_buddy_free_block);
>>   -/**
>> - * drm_buddy_free_list - free blocks
>> - *
>> - * @mm: DRM buddy manager
>> - * @objects: input list head to free blocks
>> - */
>> -void drm_buddy_free_list(struct drm_buddy *mm, struct list_head 
>> *objects)
>> +static void __drm_buddy_free_list(struct drm_buddy *mm,
>> +                  struct list_head *objects,
>> +                  bool mark_clear,
>> +                  bool mark_dirty)
>>   {
>>       struct drm_buddy_block *block, *on;
>>   +    WARN_ON(mark_dirty && mark_clear);
>> +
>>       list_for_each_entry_safe(block, on, objects, link) {
>> +        if (mark_clear)
>> +            mark_cleared(block);
>> +        else if (mark_dirty)
>> +            clear_reset(block);
>>           drm_buddy_free_block(mm, block);
>>           cond_resched();
>>       }
>>       INIT_LIST_HEAD(objects);
>>   }
>> +
>> +static void drm_buddy_free_list_internal(struct drm_buddy *mm,
>> +                     struct list_head *objects)
>> +{
>> +    /**
>> +     * Don't touch the clear/dirty bit, since allocation is still 
>> internal
>> +     * at this point. For example we might have just failed part of the
>> +     * allocation.
>> +     */
>> +    __drm_buddy_free_list(mm, objects, false, false);
>> +}
>> +
>> +/**
>> + * drm_buddy_free_list - free blocks
>> + *
>> + * @mm: DRM buddy manager
>> + * @objects: input list head to free blocks
>> + * @flags: optional flags like DRM_BUDDY_CLEARED
>> + */
>> +void drm_buddy_free_list(struct drm_buddy *mm,
>> +             struct list_head *objects,
>> +             unsigned int flags)
>> +{
>> +    bool mark_clear = flags & DRM_BUDDY_CLEARED;
>> +
>> +    __drm_buddy_free_list(mm, objects, mark_clear, !mark_clear);
>> +}
>>   EXPORT_SYMBOL(drm_buddy_free_list);
>>     static inline bool overlaps(u64 s1, u64 e1, u64 s2, u64 e2)
>> @@ -327,10 +455,19 @@ static inline bool contains(u64 s1, u64 e1, u64 
>> s2, u64 e2)
>>       return s1 <= s2 && e1 >= e2;
>>   }
>>   +static bool block_incompatible(struct drm_buddy_block *block, 
>> unsigned int flags)
>> +{
>> +    bool needs_clear = flags & DRM_BUDDY_CLEAR_ALLOCATION;
>> +
>> +    return needs_clear != drm_buddy_block_is_clear(block);
>> +}
>> +
>>   static struct drm_buddy_block *
>> -alloc_range_bias(struct drm_buddy *mm,
>> -         u64 start, u64 end,
>> -         unsigned int order)
>> +__alloc_range_bias(struct drm_buddy *mm,
>> +           u64 start, u64 end,
>> +           unsigned int order,
>> +           unsigned long flags,
>> +           bool fallback)
>>   {
>>       struct drm_buddy_block *block;
>>       struct drm_buddy_block *buddy;
>> @@ -369,7 +506,10 @@ alloc_range_bias(struct drm_buddy *mm,
>>             if (contains(start, end, block_start, block_end) &&
>>               order == drm_buddy_block_order(block)) {
>> -            /*
>> +            if (!fallback && block_incompatible(block, flags))
>> +                continue;
>> +
>> +            /**
>>                * Find the free block within the range.
>>                */
>>               if (drm_buddy_block_is_free(block))
>> @@ -391,7 +531,7 @@ alloc_range_bias(struct drm_buddy *mm,
>>       return ERR_PTR(-ENOSPC);
>>     err_undo:
>> -    /*
>> +    /**
>>        * We really don't want to leave around a bunch of split 
>> blocks, since
>>        * bigger is better, so make sure we merge everything back 
>> before we
>>        * free the allocated blocks.
>> @@ -400,30 +540,57 @@ alloc_range_bias(struct drm_buddy *mm,
>>       if (buddy &&
>>           (drm_buddy_block_is_free(block) &&
>>            drm_buddy_block_is_free(buddy)))
>> -        __drm_buddy_free(mm, block);
>> +        __drm_buddy_free(mm, block, false);
>>       return ERR_PTR(err);
>>   }
>>     static struct drm_buddy_block *
>> -get_maxblock(struct drm_buddy *mm, unsigned int order)
>> +__drm_buddy_alloc_range_bias(struct drm_buddy *mm,
>> +                 u64 start, u64 end,
>> +                 unsigned int order,
>> +                 unsigned long flags)
>> +{
>> +    struct drm_buddy_block *block;
>> +    bool fallback = false;
>> +
>> +    block = __alloc_range_bias(mm, start, end, order,
>> +                   flags, fallback);
>> +    if (IS_ERR(block) && mm->clear_avail)
>> +        return __alloc_range_bias(mm, start, end, order,
>> +                      flags, !fallback);
>> +
>> +    return block;
>> +}
>> +
>> +static struct drm_buddy_block *
>> +get_maxblock(struct drm_buddy *mm, unsigned int order,
>> +         unsigned long flags)
>>   {
>> -    struct drm_buddy_block *max_block = NULL, *node;
>> +    struct drm_buddy_block *max_block = NULL, *block = NULL;
>>       unsigned int i;
>>         for (i = order; i <= mm->max_order; ++i) {
>> -        if (!list_empty(&mm->free_list[i])) {
>> -            node = list_last_entry(&mm->free_list[i],
>> -                           struct drm_buddy_block,
>> -                           link);
>> -            if (!max_block) {
>> -                max_block = node;
>> +        struct drm_buddy_block *tmp_block;
>> +
>> +        list_for_each_entry_reverse(tmp_block, &mm->free_list[i], 
>> link) {
>> +            if (block_incompatible(tmp_block, flags))
>>                   continue;
>> -            }
>>   -            if (drm_buddy_block_offset(node) >
>> -                drm_buddy_block_offset(max_block)) {
>> -                max_block = node;
>> -            }
>> +            block = tmp_block;
>> +            break;
>> +        }
>> +
>> +        if (!block)
>> +            continue;
>> +
>> +        if (!max_block) {
>> +            max_block = block;
>> +            continue;
>> +        }
>> +
>> +        if (drm_buddy_block_offset(block) >
>> +            drm_buddy_block_offset(max_block)) {
>> +            max_block = block;
>>           }
>>       }
>>   @@ -440,11 +607,29 @@ alloc_from_freelist(struct drm_buddy *mm,
>>       int err;
>>         if (flags & DRM_BUDDY_TOPDOWN_ALLOCATION) {
>> -        block = get_maxblock(mm, order);
>> +        block = get_maxblock(mm, order, flags);
>>           if (block)
>>               /* Store the obtained block order */
>>               tmp = drm_buddy_block_order(block);
>>       } else {
>> +        for (tmp = order; tmp <= mm->max_order; ++tmp) {
>> +            struct drm_buddy_block *tmp_block;
>> +
>> +            list_for_each_entry_reverse(tmp_block, 
>> &mm->free_list[tmp], link) {
>> +                if (block_incompatible(tmp_block, flags))
>> +                    continue;
>> +
>> +                block = tmp_block;
>> +                break;
>> +            }
>> +
>> +            if (block)
>> +                break;
>> +        }
>> +    }
>> +
>> +    if (!block) {
>> +        /* Fallback method */
>>           for (tmp = order; tmp <= mm->max_order; ++tmp) {
>>               if (!list_empty(&mm->free_list[tmp])) {
>>                   block = list_last_entry(&mm->free_list[tmp],
>> @@ -454,10 +639,10 @@ alloc_from_freelist(struct drm_buddy *mm,
>>                       break;
>>               }
>>           }
>> -    }
>>   -    if (!block)
>> -        return ERR_PTR(-ENOSPC);
>> +        if (!block)
>> +            return ERR_PTR(-ENOSPC);
>> +    }
>>         BUG_ON(!drm_buddy_block_is_free(block));
>>   @@ -473,7 +658,7 @@ alloc_from_freelist(struct drm_buddy *mm,
>>     err_undo:
>>       if (tmp != order)
>> -        __drm_buddy_free(mm, block);
>> +        __drm_buddy_free(mm, block, false);
>>       return ERR_PTR(err);
>>   }
>>   @@ -524,6 +709,8 @@ static int __alloc_range(struct drm_buddy *mm,
>>               mark_allocated(block);
>>               total_allocated += drm_buddy_block_size(mm, block);
>>               mm->avail -= drm_buddy_block_size(mm, block);
>> +            if (drm_buddy_block_is_clear(block))
>> +                mm->clear_avail -= drm_buddy_block_size(mm, block);
>>               list_add_tail(&block->link, &allocated);
>>               continue;
>>           }
>> @@ -548,7 +735,7 @@ static int __alloc_range(struct drm_buddy *mm,
>>       return 0;
>>     err_undo:
>> -    /*
>> +    /**
>>        * We really don't want to leave around a bunch of split 
>> blocks, since
>>        * bigger is better, so make sure we merge everything back 
>> before we
>>        * free the allocated blocks.
>> @@ -557,14 +744,14 @@ static int __alloc_range(struct drm_buddy *mm,
>>       if (buddy &&
>>           (drm_buddy_block_is_free(block) &&
>>            drm_buddy_block_is_free(buddy)))
>> -        __drm_buddy_free(mm, block);
>> +        __drm_buddy_free(mm, block, false);
>>     err_free:
>>       if (err == -ENOSPC && total_allocated_on_err) {
>>           list_splice_tail(&allocated, blocks);
>>           *total_allocated_on_err = total_allocated;
>>       } else {
>> -        drm_buddy_free_list(mm, &allocated);
>> +        drm_buddy_free_list_internal(mm, &allocated);
>>       }
>>         return err;
>> @@ -630,11 +817,11 @@ static int __alloc_contig_try_harder(struct 
>> drm_buddy *mm,
>>               list_splice(&blocks_lhs, blocks);
>>               return 0;
>>           } else if (err != -ENOSPC) {
>> -            drm_buddy_free_list(mm, blocks);
>> +            drm_buddy_free_list_internal(mm, blocks);
>>               return err;
>>           }
>>           /* Free blocks for the next iteration */
>> -        drm_buddy_free_list(mm, blocks);
>> +        drm_buddy_free_list_internal(mm, blocks);
>>       }
>>         return -ENOSPC;
>> @@ -690,6 +877,8 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>>       list_del(&block->link);
>>       mark_free(mm, block);
>>       mm->avail += drm_buddy_block_size(mm, block);
>> +    if (drm_buddy_block_is_clear(block))
>> +        mm->clear_avail += drm_buddy_block_size(mm, block);
>>         /* Prevent recursively freeing this node */
>>       parent = block->parent;
>> @@ -701,6 +890,8 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>>       if (err) {
>>           mark_allocated(block);
>>           mm->avail -= drm_buddy_block_size(mm, block);
>> +        if (drm_buddy_block_is_clear(block))
>> +            mm->clear_avail -= drm_buddy_block_size(mm, block);
>>           list_add(&block->link, blocks);
>>       }
>>   @@ -709,13 +900,28 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>>   }
>>   EXPORT_SYMBOL(drm_buddy_block_trim);
>>   +static struct drm_buddy_block *
>> +__drm_buddy_alloc_blocks(struct drm_buddy *mm,
>> +             u64 start, u64 end,
>> +             unsigned int order,
>> +             unsigned long flags)
>> +{
>> +    if (flags & DRM_BUDDY_RANGE_ALLOCATION)
>> +        /* Allocate traversing within the range */
>> +        return  __drm_buddy_alloc_range_bias(mm, start, end,
>> +                             order, flags);
>> +    else
>> +        /* Allocate from freelist */
>> +        return alloc_from_freelist(mm, order, flags);
>> +}
>> +
>>   /**
>>    * drm_buddy_alloc_blocks - allocate power-of-two blocks
>>    *
>>    * @mm: DRM buddy manager to allocate from
>>    * @start: start of the allowed range for this block
>>    * @end: end of the allowed range for this block
>> - * @size: size of the allocation
>> + * @size: size of the allocation in bytes
>>    * @min_block_size: alignment of the allocation
>>    * @blocks: output list head to add allocated blocks
>>    * @flags: DRM_BUDDY_*_ALLOCATION flags
>> @@ -761,8 +967,18 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>>           return -EINVAL;
>>         /* Actual range allocation */
>> -    if (start + size == end)
>> -        return __drm_buddy_alloc_range(mm, start, size, NULL, blocks);
>> +    if (start + size == end) {
>> +        err =  __drm_buddy_alloc_range(mm, start, size, NULL, blocks);
>> +        if (err) {
>> +            order = ilog2(size) - ilog2(mm->chunk_size);
>> +            if (mm->clear_avail && !__force_merge(mm, order))
>> +                return __drm_buddy_alloc_range(mm, start, size, 
>> NULL, blocks);
>
> That seems strange at a glance. With an actual range allocation like 
> with intitial fb or whatever it should just find all overlapping 
> pages, splitting down where needed on the edges. Not sure why 
> force_merge would factor in here?
In case of not merged (fragmentation due to dirty and clear pages 
split), if the memory request goes into that range, we might see the 
split blocks as not free and end up returning -ENOSPC.
I found this problem when I tried to allocate the max_order where the 
start + size == end and it ends up entering into this code block and it 
returns -ENOSPC as there is no force_merge call
and the requested range max order block seen as not free. And we have an 
another issue though if we use force_merge to defragment a specific 
ordered block, there is a less probability that
we merge back the required blocks in the specific range. For now, we can 
go ahead with no force merge support for actual range allocation if we 
are sure that we use this only for initial fb etc.

If there are no major concerns, can we push these patches?

Regards,
Arun.
>> +
>> +            return err;
>> +        }
>> +
>> +        return err;
>> +    }
>>         original_size = size;
>>       original_min_size = min_block_size;
>> @@ -786,23 +1002,34 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>>           BUG_ON(order < min_order);
>>             do {
>> -            if (flags & DRM_BUDDY_RANGE_ALLOCATION)
>> -                /* Allocate traversing within the range */
>> -                block = alloc_range_bias(mm, start, end, order);
>> -            else
>> -                /* Allocate from freelist */
>> -                block = alloc_from_freelist(mm, order, flags);
>> -
>> +            block = __drm_buddy_alloc_blocks(mm, start,
>> +                             end,
>> +                             order,
>> +                             flags);
>>               if (!IS_ERR(block))
>>                   break;
>>                 if (order-- == min_order) {
>> +                /**
>> +                 * Try allocation through force merge method
>> +                 */
>> +                if (mm->clear_avail && !__force_merge(mm, min_order)) {
>> +                    block = __drm_buddy_alloc_blocks(mm, start,
>> +                                     end,
>> +                                     min_order,
>> +                                     flags);
>> +                    if (!IS_ERR(block)) {
>> +                        order = min_order;
>> +                        break;
>> +                    }
>> +                }
>> +
>> +                /**
>> +                 * Try contiguous block allocation through
>> +                 * try harder method.
>> +                 */
>>                   if (flags & DRM_BUDDY_CONTIGUOUS_ALLOCATION &&
>>                       !(flags & DRM_BUDDY_RANGE_ALLOCATION))
>> -                    /*
>> -                     * Try contiguous block allocation through
>> -                     * try harder method
>> -                     */
>>                       return __alloc_contig_try_harder(mm,
>>                                        original_size,
>>                                        original_min_size,
>> @@ -814,6 +1041,8 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>>             mark_allocated(block);
>>           mm->avail -= drm_buddy_block_size(mm, block);
>> +        if (drm_buddy_block_is_clear(block))
>> +            mm->clear_avail -= drm_buddy_block_size(mm, block);
>>           kmemleak_update_trace(block);
>>           list_add_tail(&block->link, &allocated);
>>   @@ -823,7 +1052,9 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>>               break;
>>       } while (1);
>>   -    /* Trim the allocated block to the required size */
>> +    /**
>> +     * Trim the allocated block to the required size
>> +     */
>>       if (original_size != size) {
>>           struct list_head *trim_list;
>>           LIST_HEAD(temp);
>> @@ -852,7 +1083,7 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>>       return 0;
>>     err_free:
>> -    drm_buddy_free_list(mm, &allocated);
>> +    drm_buddy_free_list_internal(mm, &allocated);
>>       return err;
>>   }
>>   EXPORT_SYMBOL(drm_buddy_alloc_blocks);
>> @@ -885,8 +1116,8 @@ void drm_buddy_print(struct drm_buddy *mm, 
>> struct drm_printer *p)
>>   {
>>       int order;
>>   -    drm_printf(p, "chunk_size: %lluKiB, total: %lluMiB, free: 
>> %lluMiB\n",
>> -           mm->chunk_size >> 10, mm->size >> 20, mm->avail >> 20);
>> +    drm_printf(p, "chunk_size: %lluKiB, total: %lluMiB, free: 
>> %lluMiB, clear_free: %lluMiB\n",
>> +           mm->chunk_size >> 10, mm->size >> 20, mm->avail >> 20, 
>> mm->clear_avail >> 20);
>>         for (order = mm->max_order; order >= 0; order--) {
>>           struct drm_buddy_block *block;
>> diff --git a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c 
>> b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
>> index 0d735d5c2b35..942345548bc3 100644
>> --- a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
>> +++ b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
>> @@ -126,7 +126,7 @@ static int i915_ttm_buddy_man_alloc(struct 
>> ttm_resource_manager *man,
>>       return 0;
>>     err_free_blocks:
>> -    drm_buddy_free_list(mm, &bman_res->blocks);
>> +    drm_buddy_free_list(mm, &bman_res->blocks, 0);
>>       mutex_unlock(&bman->lock);
>>   err_free_res:
>>       ttm_resource_fini(man, &bman_res->base);
>> @@ -141,7 +141,7 @@ static void i915_ttm_buddy_man_free(struct 
>> ttm_resource_manager *man,
>>       struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
>>         mutex_lock(&bman->lock);
>> -    drm_buddy_free_list(&bman->mm, &bman_res->blocks);
>> +    drm_buddy_free_list(&bman->mm, &bman_res->blocks, 0);
>>       bman->visible_avail += bman_res->used_visible_size;
>>       mutex_unlock(&bman->lock);
>>   @@ -345,7 +345,7 @@ int i915_ttm_buddy_man_fini(struct ttm_device 
>> *bdev, unsigned int type)
>>       ttm_set_driver_manager(bdev, type, NULL);
>>         mutex_lock(&bman->lock);
>> -    drm_buddy_free_list(mm, &bman->reserved);
>> +    drm_buddy_free_list(mm, &bman->reserved, 0);
>>       drm_buddy_fini(mm);
>>       bman->visible_avail += bman->visible_reserved;
>>       WARN_ON_ONCE(bman->visible_avail != bman->visible_size);
>> diff --git a/drivers/gpu/drm/tests/drm_buddy_test.c 
>> b/drivers/gpu/drm/tests/drm_buddy_test.c
>> index 2f32fb2f12e7..454ad9952f56 100644
>> --- a/drivers/gpu/drm/tests/drm_buddy_test.c
>> +++ b/drivers/gpu/drm/tests/drm_buddy_test.c
>> @@ -64,7 +64,7 @@ static void drm_test_buddy_alloc_contiguous(struct 
>> kunit *test)
>> DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>>                      "buddy_alloc didn't error size=%u\n", 3 * ps);
>>   -    drm_buddy_free_list(&mm, &middle);
>> +    drm_buddy_free_list(&mm, &middle, 0);
>>       KUNIT_ASSERT_TRUE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, 
>> mm_size,
>>                                  3 * ps, ps, &allocated,
>> DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>> @@ -74,7 +74,7 @@ static void drm_test_buddy_alloc_contiguous(struct 
>> kunit *test)
>> DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>>                      "buddy_alloc didn't error size=%u\n", 2 * ps);
>>   -    drm_buddy_free_list(&mm, &right);
>> +    drm_buddy_free_list(&mm, &right, 0);
>>       KUNIT_ASSERT_TRUE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, 
>> mm_size,
>>                                  3 * ps, ps, &allocated,
>> DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>> @@ -89,7 +89,7 @@ static void drm_test_buddy_alloc_contiguous(struct 
>> kunit *test)
>> DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>>                      "buddy_alloc hit an error size=%u\n", 2 * ps);
>>   -    drm_buddy_free_list(&mm, &left);
>> +    drm_buddy_free_list(&mm, &left, 0);
>>       KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, 
>> mm_size,
>>                                   3 * ps, ps, &allocated,
>> DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>> @@ -101,7 +101,7 @@ static void 
>> drm_test_buddy_alloc_contiguous(struct kunit *test)
>>         KUNIT_ASSERT_EQ(test, total, ps * 2 + ps * 3);
>>   -    drm_buddy_free_list(&mm, &allocated);
>> +    drm_buddy_free_list(&mm, &allocated, 0);
>>       drm_buddy_fini(&mm);
>>   }
>>   @@ -170,7 +170,7 @@ static void 
>> drm_test_buddy_alloc_pathological(struct kunit *test)
>>                                 top, max_order);
>>       }
>>   -    drm_buddy_free_list(&mm, &holes);
>> +    drm_buddy_free_list(&mm, &holes, 0);
>>         /* Nothing larger than blocks of chunk_size now available */
>>       for (order = 1; order <= max_order; order++) {
>> @@ -182,7 +182,7 @@ static void 
>> drm_test_buddy_alloc_pathological(struct kunit *test)
>>       }
>>         list_splice_tail(&holes, &blocks);
>> -    drm_buddy_free_list(&mm, &blocks);
>> +    drm_buddy_free_list(&mm, &blocks, 0);
>>       drm_buddy_fini(&mm);
>>   }
>>   @@ -277,7 +277,7 @@ static void 
>> drm_test_buddy_alloc_pessimistic(struct kunit *test)
>>         list_del(&block->link);
>>       drm_buddy_free_block(&mm, block);
>> -    drm_buddy_free_list(&mm, &blocks);
>> +    drm_buddy_free_list(&mm, &blocks, 0);
>>       drm_buddy_fini(&mm);
>>   }
>>   @@ -323,7 +323,7 @@ static void 
>> drm_test_buddy_alloc_optimistic(struct kunit *test)
>>                                  size, size, &tmp, flags),
>>                             "buddy_alloc unexpectedly succeeded, it 
>> should be full!");
>>   -    drm_buddy_free_list(&mm, &blocks);
>> +    drm_buddy_free_list(&mm, &blocks, 0);
>>       drm_buddy_fini(&mm);
>>   }
>>   @@ -358,7 +358,7 @@ static void drm_test_buddy_alloc_limit(struct 
>> kunit *test)
>>                           drm_buddy_block_size(&mm, block),
>>                           BIT_ULL(mm.max_order) * PAGE_SIZE);
>>   -    drm_buddy_free_list(&mm, &allocated);
>> +    drm_buddy_free_list(&mm, &allocated, 0);
>>       drm_buddy_fini(&mm);
>>   }
>>   diff --git a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c 
>> b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
>> index 115ec745e502..1ad678b62c4a 100644
>> --- a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
>> +++ b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
>> @@ -196,7 +196,7 @@ static int xe_ttm_vram_mgr_new(struct 
>> ttm_resource_manager *man,
>>       return 0;
>>     error_free_blocks:
>> -    drm_buddy_free_list(mm, &vres->blocks);
>> +    drm_buddy_free_list(mm, &vres->blocks, 0);
>>       mutex_unlock(&mgr->lock);
>>   error_fini:
>>       ttm_resource_fini(man, &vres->base);
>> @@ -214,7 +214,7 @@ static void xe_ttm_vram_mgr_del(struct 
>> ttm_resource_manager *man,
>>       struct drm_buddy *mm = &mgr->mm;
>>         mutex_lock(&mgr->lock);
>> -    drm_buddy_free_list(mm, &vres->blocks);
>> +    drm_buddy_free_list(mm, &vres->blocks, 0);
>>       mgr->visible_avail += vres->used_visible_size;
>>       mutex_unlock(&mgr->lock);
>>   diff --git a/include/drm/drm_buddy.h b/include/drm/drm_buddy.h
>> index a5b39fc01003..82570f77e817 100644
>> --- a/include/drm/drm_buddy.h
>> +++ b/include/drm/drm_buddy.h
>> @@ -25,6 +25,8 @@
>>   #define DRM_BUDDY_RANGE_ALLOCATION        BIT(0)
>>   #define DRM_BUDDY_TOPDOWN_ALLOCATION        BIT(1)
>>   #define DRM_BUDDY_CONTIGUOUS_ALLOCATION        BIT(2)
>> +#define DRM_BUDDY_CLEAR_ALLOCATION        BIT(3)
>> +#define DRM_BUDDY_CLEARED            BIT(4)
>>     struct drm_buddy_block {
>>   #define DRM_BUDDY_HEADER_OFFSET GENMASK_ULL(63, 12)
>> @@ -32,8 +34,9 @@ struct drm_buddy_block {
>>   #define   DRM_BUDDY_ALLOCATED       (1 << 10)
>>   #define   DRM_BUDDY_FREE       (2 << 10)
>>   #define   DRM_BUDDY_SPLIT       (3 << 10)
>> +#define DRM_BUDDY_HEADER_CLEAR  GENMASK_ULL(9, 9)
>>   /* Free to be used, if needed in the future */
>> -#define DRM_BUDDY_HEADER_UNUSED GENMASK_ULL(9, 6)
>> +#define DRM_BUDDY_HEADER_UNUSED GENMASK_ULL(8, 6)
>>   #define DRM_BUDDY_HEADER_ORDER  GENMASK_ULL(5, 0)
>>       u64 header;
>>   @@ -86,6 +89,7 @@ struct drm_buddy {
>>       u64 chunk_size;
>>       u64 size;
>>       u64 avail;
>> +    u64 clear_avail;
>>   };
>>     static inline u64
>> @@ -112,6 +116,12 @@ drm_buddy_block_is_allocated(struct 
>> drm_buddy_block *block)
>>       return drm_buddy_block_state(block) == DRM_BUDDY_ALLOCATED;
>>   }
>>   +static inline bool
>> +drm_buddy_block_is_clear(struct drm_buddy_block *block)
>> +{
>> +    return block->header & DRM_BUDDY_HEADER_CLEAR;
>> +}
>> +
>>   static inline bool
>>   drm_buddy_block_is_free(struct drm_buddy_block *block)
>>   {
>> @@ -150,7 +160,9 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>>     void drm_buddy_free_block(struct drm_buddy *mm, struct 
>> drm_buddy_block *block);
>>   -void drm_buddy_free_list(struct drm_buddy *mm, struct list_head 
>> *objects);
>> +void drm_buddy_free_list(struct drm_buddy *mm,
>> +             struct list_head *objects,
>> +             unsigned int flags);
>>     void drm_buddy_print(struct drm_buddy *mm, struct drm_printer *p);
>>   void drm_buddy_block_print(struct drm_buddy *mm,

Matthew Auld March 28, 2024, 4:48 p.m. UTC | #4

On 28/03/2024 16:07, Paneer Selvam, Arunpravin wrote:
> Hi Matthew,
> 
> On 3/26/2024 11:39 PM, Matthew Auld wrote:
>> On 18/03/2024 21:40, Arunpravin Paneer Selvam wrote:
>>> - Add tracking clear page feature.
>>>
>>> - Driver should enable the DRM_BUDDY_CLEARED flag if it
>>>    successfully clears the blocks in the free path. On the otherhand,
>>>    DRM buddy marks each block as cleared.
>>>
>>> - Track the available cleared pages size
>>>
>>> - If driver requests cleared memory we prefer cleared memory
>>>    but fallback to uncleared if we can't find the cleared blocks.
>>>    when driver requests uncleared memory we try to use uncleared but
>>>    fallback to cleared memory if necessary.
>>>
>>> - When a block gets freed we clear it and mark the freed block as 
>>> cleared,
>>>    when there are buddies which are cleared as well we can merge them.
>>>    Otherwise, we prefer to keep the blocks as separated.
>>>
>>> - Add a function to support defragmentation.
>>>
>>> v1:
>>>    - Depends on the flag check DRM_BUDDY_CLEARED, enable the block as
>>>      cleared. Else, reset the clear flag for each block in the 
>>> list(Christian)
>>>    - For merging the 2 cleared blocks compare as below,
>>>      drm_buddy_is_clear(block) != drm_buddy_is_clear(buddy)(Christian)
>>>    - Defragment the memory beginning from min_order
>>>      till the required memory space is available.
>>>
>>> v2: (Matthew)
>>>    - Add a wrapper drm_buddy_free_list_internal for the freeing of 
>>> blocks
>>>      operation within drm buddy.
>>>    - Write a macro block_incompatible() to allocate the required blocks.
>>>    - Update the xe driver for the drm_buddy_free_list change in 
>>> arguments.
>>>    - add a warning if the two blocks are incompatible on
>>>      defragmentation
>>>    - call full defragmentation in the fini() function
>>>    - place a condition to test if min_order is equal to 0
>>>    - replace the list with safe_reverse() variant as we might
>>>      remove the block from the list.
>>>
>>> v3:
>>>    - fix Gitlab user reported lockup issue.
>>>    - Keep DRM_BUDDY_HEADER_CLEAR define sorted(Matthew)
>>>    - modify to pass the root order instead max_order in fini()
>>>      function(Matthew)
>>>    - change bool 1 to true(Matthew)
>>>    - add check if min_block_size is power of 2(Matthew)
>>>    - modify the min_block_size datatype to u64(Matthew)
>>>
>>> v4:
>>>    - rename the function drm_buddy_defrag with __force_merge.
>>>    - Include __force_merge directly in drm buddy file and remove
>>>      the defrag use in amdgpu driver.
>>>    - Remove list_empty() check(Matthew)
>>>    - Remove unnecessary space, headers and placement of new 
>>> variables(Matthew)
>>>    - Add a unit test case(Matthew)
>>>
>>> Signed-off-by: Arunpravin Paneer Selvam 
>>> <[e-mail]>
>>> Signed-off-by: Matthew Auld <[e-mail]>
>>> Suggested-by: Christian König <[e-mail]>
>>> Suggested-by: Matthew Auld <[e-mail]>
>>> ---
>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c  |   6 +-
>>>   drivers/gpu/drm/drm_buddy.c                   | 427 ++++++++++++++----
>>>   drivers/gpu/drm/i915/i915_ttm_buddy_manager.c |   6 +-
>>>   drivers/gpu/drm/tests/drm_buddy_test.c        |  18 +-
>>>   drivers/gpu/drm/xe/xe_ttm_vram_mgr.c          |   4 +-
>>>   include/drm/drm_buddy.h                       |  16 +-
>>>   6 files changed, 360 insertions(+), 117 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c 
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>>> index 8db880244324..c0c851409241 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>>> @@ -571,7 +571,7 @@ static int amdgpu_vram_mgr_new(struct 
>>> ttm_resource_manager *man,
>>>       return 0;
>>>     error_free_blocks:
>>> -    drm_buddy_free_list(mm, &vres->blocks);
>>> +    drm_buddy_free_list(mm, &vres->blocks, 0);
>>>       mutex_unlock(&mgr->lock);
>>>   error_fini:
>>>       ttm_resource_fini(man, &vres->base);
>>> @@ -604,7 +604,7 @@ static void amdgpu_vram_mgr_del(struct 
>>> ttm_resource_manager *man,
>>>         amdgpu_vram_mgr_do_reserve(man);
>>>   -    drm_buddy_free_list(mm, &vres->blocks);
>>> +    drm_buddy_free_list(mm, &vres->blocks, 0);
>>>       mutex_unlock(&mgr->lock);
>>>         atomic64_sub(vis_usage, &mgr->vis_usage);
>>> @@ -912,7 +912,7 @@ void amdgpu_vram_mgr_fini(struct amdgpu_device 
>>> *adev)
>>>           kfree(rsv);
>>>         list_for_each_entry_safe(rsv, temp, &mgr->reserved_pages, 
>>> blocks) {
>>> -        drm_buddy_free_list(&mgr->mm, &rsv->allocated);
>>> +        drm_buddy_free_list(&mgr->mm, &rsv->allocated, 0);
>>>           kfree(rsv);
>>>       }
>>>       if (!adev->gmc.is_app_apu)
>>> diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c
>>> index c4222b886db7..625a30a6b855 100644
>>> --- a/drivers/gpu/drm/drm_buddy.c
>>> +++ b/drivers/gpu/drm/drm_buddy.c
>>> @@ -38,8 +38,8 @@ static void drm_block_free(struct drm_buddy *mm,
>>>       kmem_cache_free(slab_blocks, block);
>>>   }
>>>   -static void list_insert_sorted(struct drm_buddy *mm,
>>> -                   struct drm_buddy_block *block)
>>> +static void list_insert(struct drm_buddy *mm,
>>> +            struct drm_buddy_block *block)
>>>   {
>>>       struct drm_buddy_block *node;
>>>       struct list_head *head;
>>> @@ -57,6 +57,16 @@ static void list_insert_sorted(struct drm_buddy *mm,
>>>       __list_add(&block->link, node->link.prev, &node->link);
>>>   }
>>>   +static void clear_reset(struct drm_buddy_block *block)
>>> +{
>>> +    block->header &= ~DRM_BUDDY_HEADER_CLEAR;
>>> +}
>>> +
>>> +static void mark_cleared(struct drm_buddy_block *block)
>>> +{
>>> +    block->header |= DRM_BUDDY_HEADER_CLEAR;
>>> +}
>>> +
>>>   static void mark_allocated(struct drm_buddy_block *block)
>>>   {
>>>       block->header &= ~DRM_BUDDY_HEADER_STATE;
>>> @@ -71,7 +81,7 @@ static void mark_free(struct drm_buddy *mm,
>>>       block->header &= ~DRM_BUDDY_HEADER_STATE;
>>>       block->header |= DRM_BUDDY_FREE;
>>>   -    list_insert_sorted(mm, block);
>>> +    list_insert(mm, block);
>>>   }
>>>     static void mark_split(struct drm_buddy_block *block)
>>> @@ -82,6 +92,114 @@ static void mark_split(struct drm_buddy_block 
>>> *block)
>>>       list_del(&block->link);
>>>   }
>>>   +static struct drm_buddy_block *
>>> +__get_buddy(struct drm_buddy_block *block)
>>> +{
>>> +    struct drm_buddy_block *parent;
>>> +
>>> +    parent = block->parent;
>>> +    if (!parent)
>>> +        return NULL;
>>> +
>>> +    if (parent->left == block)
>>> +        return parent->right;
>>> +
>>> +    return parent->left;
>>> +}
>>> +
>>> +static unsigned int __drm_buddy_free(struct drm_buddy *mm,
>>> +                     struct drm_buddy_block *block,
>>> +                     bool force_merge)
>>> +{
>>> +    struct drm_buddy_block *parent;
>>> +    unsigned int order;
>>> +
>>> +    while ((parent = block->parent)) {
>>> +        struct drm_buddy_block *buddy;
>>> +
>>> +        buddy = __get_buddy(block);
>>> +
>>> +        if (!drm_buddy_block_is_free(buddy))
>>> +            break;
>>> +
>>> +        if (!force_merge) {
>>> +            /**
>>
>> Not really valid kernel-doc AFAIK. I think drop the extra *. Below also.
>>
>>> +             * Check the block and its buddy clear state and exit
>>> +             * the loop if they both have the dissimilar state.
>>> +             */
>>> +            if (drm_buddy_block_is_clear(block) !=
>>> +                drm_buddy_block_is_clear(buddy))
>>> +                break;
>>> +
>>> +            if (drm_buddy_block_is_clear(block))
>>> +                mark_cleared(parent);
>>> +        }
>>> +
>>> +        list_del(&buddy->link);
>>> +        if (force_merge && drm_buddy_block_is_clear(buddy))
>>> +            mm->clear_avail -= drm_buddy_block_size(mm, buddy);
>>> +
>>> +        drm_block_free(mm, block);
>>> +        drm_block_free(mm, buddy);
>>> +
>>> +        block = parent;
>>> +    }
>>> +
>>> +    order = drm_buddy_block_order(block);
>>> +    mark_free(mm, block);
>>> +
>>> +    return order;
>>> +}
>>> +
>>> +static int __force_merge(struct drm_buddy *mm,
>>> +             unsigned int min_order)
>>> +{
>>> +    unsigned int order;
>>> +    int i;
>>> +
>>> +    if (!min_order)
>>> +        return -ENOMEM;
>>> +
>>> +    if (min_order > mm->max_order)
>>> +        return -EINVAL;
>>> +
>>> +    for (i = min_order - 1; i >= 0; i--) {
>>> +        struct drm_buddy_block *block, *prev;
>>> +
>>> +        list_for_each_entry_safe_reverse(block, prev, 
>>> &mm->free_list[i], link) {
>>> +            struct drm_buddy_block *buddy;
>>> +
>>> +            if (!block->parent)
>>> +                continue;
>>> +
>>> +            buddy = __get_buddy(block);
>>> +            if (!drm_buddy_block_is_free(buddy))
>>> +                continue;
>>> +
>>> +            WARN_ON(drm_buddy_block_is_clear(block) ==
>>> +                drm_buddy_block_is_clear(buddy));
>>> +
>>> +            /**
>>> +             * If the prev block is same as buddy, don't access the
>>> +             * block in the next iteration as we would free the
>>> +             * buddy block as part of the free function.
>>> +             */
>>> +            if (prev == buddy)
>>> +                prev = list_prev_entry(prev, link);
>>> +
>>> +            list_del(&block->link);
>>> +            if (drm_buddy_block_is_clear(block))
>>> +                mm->clear_avail -= drm_buddy_block_size(mm, block);
>>> +
>>> +            order = __drm_buddy_free(mm, block, true);
>>> +            if (order >= min_order)
>>> +                return 0;
>>> +        }
>>> +    }
>>> +
>>> +    return -ENOMEM;
>>> +}
>>> +
>>>   /**
>>>    * drm_buddy_init - init memory manager
>>>    *
>>> @@ -137,7 +255,7 @@ int drm_buddy_init(struct drm_buddy *mm, u64 
>>> size, u64 chunk_size)
>>>       offset = 0;
>>>       i = 0;
>>>   -    /*
>>> +    /**
>>>        * Split into power-of-two blocks, in case we are given a size 
>>> that is
>>>        * not itself a power-of-two.
>>>        */
>>> @@ -186,11 +304,21 @@ EXPORT_SYMBOL(drm_buddy_init);
>>>    */
>>>   void drm_buddy_fini(struct drm_buddy *mm)
>>>   {
>>> +    u64 root_size, size;
>>> +    unsigned int order;
>>>       int i;
>>>   +    size = mm->size;
>>> +
>>>       for (i = 0; i < mm->n_roots; ++i) {
>>> +        order = ilog2(size) - ilog2(mm->chunk_size);
>>> +        __force_merge(mm, order);
>>> +
>>>           WARN_ON(!drm_buddy_block_is_free(mm->roots[i]));
>>>           drm_block_free(mm, mm->roots[i]);
>>> +
>>> +        root_size = mm->chunk_size << order;
>>> +        size -= root_size;
>>>       }
>>>         WARN_ON(mm->avail != mm->size);
>>> @@ -223,26 +351,17 @@ static int split_block(struct drm_buddy *mm,
>>>       mark_free(mm, block->left);
>>>       mark_free(mm, block->right);
>>>   +    if (drm_buddy_block_is_clear(block)) {
>>> +        mark_cleared(block->left);
>>> +        mark_cleared(block->right);
>>> +        clear_reset(block);
>>> +    }
>>> +
>>>       mark_split(block);
>>>         return 0;
>>>   }
>>>   -static struct drm_buddy_block *
>>> -__get_buddy(struct drm_buddy_block *block)
>>> -{
>>> -    struct drm_buddy_block *parent;
>>> -
>>> -    parent = block->parent;
>>> -    if (!parent)
>>> -        return NULL;
>>> -
>>> -    if (parent->left == block)
>>> -        return parent->right;
>>> -
>>> -    return parent->left;
>>> -}
>>> -
>>>   /**
>>>    * drm_get_buddy - get buddy address
>>>    *
>>> @@ -260,30 +379,6 @@ drm_get_buddy(struct drm_buddy_block *block)
>>>   }
>>>   EXPORT_SYMBOL(drm_get_buddy);
>>>   -static void __drm_buddy_free(struct drm_buddy *mm,
>>> -                 struct drm_buddy_block *block)
>>> -{
>>> -    struct drm_buddy_block *parent;
>>> -
>>> -    while ((parent = block->parent)) {
>>> -        struct drm_buddy_block *buddy;
>>> -
>>> -        buddy = __get_buddy(block);
>>> -
>>> -        if (!drm_buddy_block_is_free(buddy))
>>> -            break;
>>> -
>>> -        list_del(&buddy->link);
>>> -
>>> -        drm_block_free(mm, block);
>>> -        drm_block_free(mm, buddy);
>>> -
>>> -        block = parent;
>>> -    }
>>> -
>>> -    mark_free(mm, block);
>>> -}
>>> -
>>>   /**
>>>    * drm_buddy_free_block - free a block
>>>    *
>>> @@ -295,26 +390,59 @@ void drm_buddy_free_block(struct drm_buddy *mm,
>>>   {
>>>       BUG_ON(!drm_buddy_block_is_allocated(block));
>>>       mm->avail += drm_buddy_block_size(mm, block);
>>> -    __drm_buddy_free(mm, block);
>>> +    if (drm_buddy_block_is_clear(block))
>>> +        mm->clear_avail += drm_buddy_block_size(mm, block);
>>> +
>>> +    __drm_buddy_free(mm, block, false);
>>>   }
>>>   EXPORT_SYMBOL(drm_buddy_free_block);
>>>   -/**
>>> - * drm_buddy_free_list - free blocks
>>> - *
>>> - * @mm: DRM buddy manager
>>> - * @objects: input list head to free blocks
>>> - */
>>> -void drm_buddy_free_list(struct drm_buddy *mm, struct list_head 
>>> *objects)
>>> +static void __drm_buddy_free_list(struct drm_buddy *mm,
>>> +                  struct list_head *objects,
>>> +                  bool mark_clear,
>>> +                  bool mark_dirty)
>>>   {
>>>       struct drm_buddy_block *block, *on;
>>>   +    WARN_ON(mark_dirty && mark_clear);
>>> +
>>>       list_for_each_entry_safe(block, on, objects, link) {
>>> +        if (mark_clear)
>>> +            mark_cleared(block);
>>> +        else if (mark_dirty)
>>> +            clear_reset(block);
>>>           drm_buddy_free_block(mm, block);
>>>           cond_resched();
>>>       }
>>>       INIT_LIST_HEAD(objects);
>>>   }
>>> +
>>> +static void drm_buddy_free_list_internal(struct drm_buddy *mm,
>>> +                     struct list_head *objects)
>>> +{
>>> +    /**
>>> +     * Don't touch the clear/dirty bit, since allocation is still 
>>> internal
>>> +     * at this point. For example we might have just failed part of the
>>> +     * allocation.
>>> +     */
>>> +    __drm_buddy_free_list(mm, objects, false, false);
>>> +}
>>> +
>>> +/**
>>> + * drm_buddy_free_list - free blocks
>>> + *
>>> + * @mm: DRM buddy manager
>>> + * @objects: input list head to free blocks
>>> + * @flags: optional flags like DRM_BUDDY_CLEARED
>>> + */
>>> +void drm_buddy_free_list(struct drm_buddy *mm,
>>> +             struct list_head *objects,
>>> +             unsigned int flags)
>>> +{
>>> +    bool mark_clear = flags & DRM_BUDDY_CLEARED;
>>> +
>>> +    __drm_buddy_free_list(mm, objects, mark_clear, !mark_clear);
>>> +}
>>>   EXPORT_SYMBOL(drm_buddy_free_list);
>>>     static inline bool overlaps(u64 s1, u64 e1, u64 s2, u64 e2)
>>> @@ -327,10 +455,19 @@ static inline bool contains(u64 s1, u64 e1, u64 
>>> s2, u64 e2)
>>>       return s1 <= s2 && e1 >= e2;
>>>   }
>>>   +static bool block_incompatible(struct drm_buddy_block *block, 
>>> unsigned int flags)
>>> +{
>>> +    bool needs_clear = flags & DRM_BUDDY_CLEAR_ALLOCATION;
>>> +
>>> +    return needs_clear != drm_buddy_block_is_clear(block);
>>> +}
>>> +
>>>   static struct drm_buddy_block *
>>> -alloc_range_bias(struct drm_buddy *mm,
>>> -         u64 start, u64 end,
>>> -         unsigned int order)
>>> +__alloc_range_bias(struct drm_buddy *mm,
>>> +           u64 start, u64 end,
>>> +           unsigned int order,
>>> +           unsigned long flags,
>>> +           bool fallback)
>>>   {
>>>       struct drm_buddy_block *block;
>>>       struct drm_buddy_block *buddy;
>>> @@ -369,7 +506,10 @@ alloc_range_bias(struct drm_buddy *mm,
>>>             if (contains(start, end, block_start, block_end) &&
>>>               order == drm_buddy_block_order(block)) {
>>> -            /*
>>> +            if (!fallback && block_incompatible(block, flags))
>>> +                continue;
>>> +
>>> +            /**
>>>                * Find the free block within the range.
>>>                */
>>>               if (drm_buddy_block_is_free(block))
>>> @@ -391,7 +531,7 @@ alloc_range_bias(struct drm_buddy *mm,
>>>       return ERR_PTR(-ENOSPC);
>>>     err_undo:
>>> -    /*
>>> +    /**
>>>        * We really don't want to leave around a bunch of split 
>>> blocks, since
>>>        * bigger is better, so make sure we merge everything back 
>>> before we
>>>        * free the allocated blocks.
>>> @@ -400,30 +540,57 @@ alloc_range_bias(struct drm_buddy *mm,
>>>       if (buddy &&
>>>           (drm_buddy_block_is_free(block) &&
>>>            drm_buddy_block_is_free(buddy)))
>>> -        __drm_buddy_free(mm, block);
>>> +        __drm_buddy_free(mm, block, false);
>>>       return ERR_PTR(err);
>>>   }
>>>     static struct drm_buddy_block *
>>> -get_maxblock(struct drm_buddy *mm, unsigned int order)
>>> +__drm_buddy_alloc_range_bias(struct drm_buddy *mm,
>>> +                 u64 start, u64 end,
>>> +                 unsigned int order,
>>> +                 unsigned long flags)
>>> +{
>>> +    struct drm_buddy_block *block;
>>> +    bool fallback = false;
>>> +
>>> +    block = __alloc_range_bias(mm, start, end, order,
>>> +                   flags, fallback);
>>> +    if (IS_ERR(block) && mm->clear_avail)
>>> +        return __alloc_range_bias(mm, start, end, order,
>>> +                      flags, !fallback);
>>> +
>>> +    return block;
>>> +}
>>> +
>>> +static struct drm_buddy_block *
>>> +get_maxblock(struct drm_buddy *mm, unsigned int order,
>>> +         unsigned long flags)
>>>   {
>>> -    struct drm_buddy_block *max_block = NULL, *node;
>>> +    struct drm_buddy_block *max_block = NULL, *block = NULL;
>>>       unsigned int i;
>>>         for (i = order; i <= mm->max_order; ++i) {
>>> -        if (!list_empty(&mm->free_list[i])) {
>>> -            node = list_last_entry(&mm->free_list[i],
>>> -                           struct drm_buddy_block,
>>> -                           link);
>>> -            if (!max_block) {
>>> -                max_block = node;
>>> +        struct drm_buddy_block *tmp_block;
>>> +
>>> +        list_for_each_entry_reverse(tmp_block, &mm->free_list[i], 
>>> link) {
>>> +            if (block_incompatible(tmp_block, flags))
>>>                   continue;
>>> -            }
>>>   -            if (drm_buddy_block_offset(node) >
>>> -                drm_buddy_block_offset(max_block)) {
>>> -                max_block = node;
>>> -            }
>>> +            block = tmp_block;
>>> +            break;
>>> +        }
>>> +
>>> +        if (!block)
>>> +            continue;
>>> +
>>> +        if (!max_block) {
>>> +            max_block = block;
>>> +            continue;
>>> +        }
>>> +
>>> +        if (drm_buddy_block_offset(block) >
>>> +            drm_buddy_block_offset(max_block)) {
>>> +            max_block = block;
>>>           }
>>>       }
>>>   @@ -440,11 +607,29 @@ alloc_from_freelist(struct drm_buddy *mm,
>>>       int err;
>>>         if (flags & DRM_BUDDY_TOPDOWN_ALLOCATION) {
>>> -        block = get_maxblock(mm, order);
>>> +        block = get_maxblock(mm, order, flags);
>>>           if (block)
>>>               /* Store the obtained block order */
>>>               tmp = drm_buddy_block_order(block);
>>>       } else {
>>> +        for (tmp = order; tmp <= mm->max_order; ++tmp) {
>>> +            struct drm_buddy_block *tmp_block;
>>> +
>>> +            list_for_each_entry_reverse(tmp_block, 
>>> &mm->free_list[tmp], link) {
>>> +                if (block_incompatible(tmp_block, flags))
>>> +                    continue;
>>> +
>>> +                block = tmp_block;
>>> +                break;
>>> +            }
>>> +
>>> +            if (block)
>>> +                break;
>>> +        }
>>> +    }
>>> +
>>> +    if (!block) {
>>> +        /* Fallback method */
>>>           for (tmp = order; tmp <= mm->max_order; ++tmp) {
>>>               if (!list_empty(&mm->free_list[tmp])) {
>>>                   block = list_last_entry(&mm->free_list[tmp],
>>> @@ -454,10 +639,10 @@ alloc_from_freelist(struct drm_buddy *mm,
>>>                       break;
>>>               }
>>>           }
>>> -    }
>>>   -    if (!block)
>>> -        return ERR_PTR(-ENOSPC);
>>> +        if (!block)
>>> +            return ERR_PTR(-ENOSPC);
>>> +    }
>>>         BUG_ON(!drm_buddy_block_is_free(block));
>>>   @@ -473,7 +658,7 @@ alloc_from_freelist(struct drm_buddy *mm,
>>>     err_undo:
>>>       if (tmp != order)
>>> -        __drm_buddy_free(mm, block);
>>> +        __drm_buddy_free(mm, block, false);
>>>       return ERR_PTR(err);
>>>   }
>>>   @@ -524,6 +709,8 @@ static int __alloc_range(struct drm_buddy *mm,
>>>               mark_allocated(block);
>>>               total_allocated += drm_buddy_block_size(mm, block);
>>>               mm->avail -= drm_buddy_block_size(mm, block);
>>> +            if (drm_buddy_block_is_clear(block))
>>> +                mm->clear_avail -= drm_buddy_block_size(mm, block);
>>>               list_add_tail(&block->link, &allocated);
>>>               continue;
>>>           }
>>> @@ -548,7 +735,7 @@ static int __alloc_range(struct drm_buddy *mm,
>>>       return 0;
>>>     err_undo:
>>> -    /*
>>> +    /**
>>>        * We really don't want to leave around a bunch of split 
>>> blocks, since
>>>        * bigger is better, so make sure we merge everything back 
>>> before we
>>>        * free the allocated blocks.
>>> @@ -557,14 +744,14 @@ static int __alloc_range(struct drm_buddy *mm,
>>>       if (buddy &&
>>>           (drm_buddy_block_is_free(block) &&
>>>            drm_buddy_block_is_free(buddy)))
>>> -        __drm_buddy_free(mm, block);
>>> +        __drm_buddy_free(mm, block, false);
>>>     err_free:
>>>       if (err == -ENOSPC && total_allocated_on_err) {
>>>           list_splice_tail(&allocated, blocks);
>>>           *total_allocated_on_err = total_allocated;
>>>       } else {
>>> -        drm_buddy_free_list(mm, &allocated);
>>> +        drm_buddy_free_list_internal(mm, &allocated);
>>>       }
>>>         return err;
>>> @@ -630,11 +817,11 @@ static int __alloc_contig_try_harder(struct 
>>> drm_buddy *mm,
>>>               list_splice(&blocks_lhs, blocks);
>>>               return 0;
>>>           } else if (err != -ENOSPC) {
>>> -            drm_buddy_free_list(mm, blocks);
>>> +            drm_buddy_free_list_internal(mm, blocks);
>>>               return err;
>>>           }
>>>           /* Free blocks for the next iteration */
>>> -        drm_buddy_free_list(mm, blocks);
>>> +        drm_buddy_free_list_internal(mm, blocks);
>>>       }
>>>         return -ENOSPC;
>>> @@ -690,6 +877,8 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>>>       list_del(&block->link);
>>>       mark_free(mm, block);
>>>       mm->avail += drm_buddy_block_size(mm, block);
>>> +    if (drm_buddy_block_is_clear(block))
>>> +        mm->clear_avail += drm_buddy_block_size(mm, block);
>>>         /* Prevent recursively freeing this node */
>>>       parent = block->parent;
>>> @@ -701,6 +890,8 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>>>       if (err) {
>>>           mark_allocated(block);
>>>           mm->avail -= drm_buddy_block_size(mm, block);
>>> +        if (drm_buddy_block_is_clear(block))
>>> +            mm->clear_avail -= drm_buddy_block_size(mm, block);
>>>           list_add(&block->link, blocks);
>>>       }
>>>   @@ -709,13 +900,28 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>>>   }
>>>   EXPORT_SYMBOL(drm_buddy_block_trim);
>>>   +static struct drm_buddy_block *
>>> +__drm_buddy_alloc_blocks(struct drm_buddy *mm,
>>> +             u64 start, u64 end,
>>> +             unsigned int order,
>>> +             unsigned long flags)
>>> +{
>>> +    if (flags & DRM_BUDDY_RANGE_ALLOCATION)
>>> +        /* Allocate traversing within the range */
>>> +        return  __drm_buddy_alloc_range_bias(mm, start, end,
>>> +                             order, flags);
>>> +    else
>>> +        /* Allocate from freelist */
>>> +        return alloc_from_freelist(mm, order, flags);
>>> +}
>>> +
>>>   /**
>>>    * drm_buddy_alloc_blocks - allocate power-of-two blocks
>>>    *
>>>    * @mm: DRM buddy manager to allocate from
>>>    * @start: start of the allowed range for this block
>>>    * @end: end of the allowed range for this block
>>> - * @size: size of the allocation
>>> + * @size: size of the allocation in bytes
>>>    * @min_block_size: alignment of the allocation
>>>    * @blocks: output list head to add allocated blocks
>>>    * @flags: DRM_BUDDY_*_ALLOCATION flags
>>> @@ -761,8 +967,18 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>>>           return -EINVAL;
>>>         /* Actual range allocation */
>>> -    if (start + size == end)
>>> -        return __drm_buddy_alloc_range(mm, start, size, NULL, blocks);
>>> +    if (start + size == end) {
>>> +        err =  __drm_buddy_alloc_range(mm, start, size, NULL, blocks);
>>> +        if (err) {
>>> +            order = ilog2(size) - ilog2(mm->chunk_size);
>>> +            if (mm->clear_avail && !__force_merge(mm, order))
>>> +                return __drm_buddy_alloc_range(mm, start, size, 
>>> NULL, blocks);
>>
>> That seems strange at a glance. With an actual range allocation like 
>> with intitial fb or whatever it should just find all overlapping 
>> pages, splitting down where needed on the edges. Not sure why 
>> force_merge would factor in here?
> In case of not merged (fragmentation due to dirty and clear pages 
> split), if the memory request goes into that range, we might see the 
> split blocks as not free and end up returning -ENOSPC.
> I found this problem when I tried to allocate the max_order where the 
> start + size == end and it ends up entering into this code block and it 
> returns -ENOSPC as there is no force_merge call
> and the requested range max order block seen as not free. And we have an 
> another issue though if we use force_merge to defragment a specific 
> ordered block, there is a less probability that
> we merge back the required blocks in the specific range. For now, we can 
> go ahead with no force merge support for actual range allocation if we 
> are sure that we use this only for initial fb etc.

Ah right, now I see. But AFAICT trouble is if we say allocate 8K range 
at some specific offset, like above, which fails due to clear/dirty 
split then calling force_merge(order(8K)) is not always going to help. 
It will just force merge enough for 8K, but that might not be the 8K at 
the offset we were looking for, so it still fails. I think perhaps 
update the dfs in alloc_range to not bail when contains && split. Or I 
think other option is to force merge the entire address space on err. 
Other ideas?

> 
> If there are no major concerns, can we push these patches?
> 
> Regards,
> Arun.
>>> +
>>> +            return err;
>>> +        }
>>> +
>>> +        return err;
>>> +    }
>>>         original_size = size;
>>>       original_min_size = min_block_size;
>>> @@ -786,23 +1002,34 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>>>           BUG_ON(order < min_order);
>>>             do {
>>> -            if (flags & DRM_BUDDY_RANGE_ALLOCATION)
>>> -                /* Allocate traversing within the range */
>>> -                block = alloc_range_bias(mm, start, end, order);
>>> -            else
>>> -                /* Allocate from freelist */
>>> -                block = alloc_from_freelist(mm, order, flags);
>>> -
>>> +            block = __drm_buddy_alloc_blocks(mm, start,
>>> +                             end,
>>> +                             order,
>>> +                             flags);
>>>               if (!IS_ERR(block))
>>>                   break;
>>>                 if (order-- == min_order) {
>>> +                /**
>>> +                 * Try allocation through force merge method
>>> +                 */
>>> +                if (mm->clear_avail && !__force_merge(mm, min_order)) {
>>> +                    block = __drm_buddy_alloc_blocks(mm, start,
>>> +                                     end,
>>> +                                     min_order,
>>> +                                     flags);
>>> +                    if (!IS_ERR(block)) {
>>> +                        order = min_order;
>>> +                        break;
>>> +                    }
>>> +                }
>>> +
>>> +                /**
>>> +                 * Try contiguous block allocation through
>>> +                 * try harder method.
>>> +                 */
>>>                   if (flags & DRM_BUDDY_CONTIGUOUS_ALLOCATION &&
>>>                       !(flags & DRM_BUDDY_RANGE_ALLOCATION))
>>> -                    /*
>>> -                     * Try contiguous block allocation through
>>> -                     * try harder method
>>> -                     */
>>>                       return __alloc_contig_try_harder(mm,
>>>                                        original_size,
>>>                                        original_min_size,
>>> @@ -814,6 +1041,8 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>>>             mark_allocated(block);
>>>           mm->avail -= drm_buddy_block_size(mm, block);
>>> +        if (drm_buddy_block_is_clear(block))
>>> +            mm->clear_avail -= drm_buddy_block_size(mm, block);
>>>           kmemleak_update_trace(block);
>>>           list_add_tail(&block->link, &allocated);
>>>   @@ -823,7 +1052,9 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>>>               break;
>>>       } while (1);
>>>   -    /* Trim the allocated block to the required size */
>>> +    /**
>>> +     * Trim the allocated block to the required size
>>> +     */
>>>       if (original_size != size) {
>>>           struct list_head *trim_list;
>>>           LIST_HEAD(temp);
>>> @@ -852,7 +1083,7 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>>>       return 0;
>>>     err_free:
>>> -    drm_buddy_free_list(mm, &allocated);
>>> +    drm_buddy_free_list_internal(mm, &allocated);
>>>       return err;
>>>   }
>>>   EXPORT_SYMBOL(drm_buddy_alloc_blocks);
>>> @@ -885,8 +1116,8 @@ void drm_buddy_print(struct drm_buddy *mm, 
>>> struct drm_printer *p)
>>>   {
>>>       int order;
>>>   -    drm_printf(p, "chunk_size: %lluKiB, total: %lluMiB, free: 
>>> %lluMiB\n",
>>> -           mm->chunk_size >> 10, mm->size >> 20, mm->avail >> 20);
>>> +    drm_printf(p, "chunk_size: %lluKiB, total: %lluMiB, free: 
>>> %lluMiB, clear_free: %lluMiB\n",
>>> +           mm->chunk_size >> 10, mm->size >> 20, mm->avail >> 20, 
>>> mm->clear_avail >> 20);
>>>         for (order = mm->max_order; order >= 0; order--) {
>>>           struct drm_buddy_block *block;
>>> diff --git a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c 
>>> b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
>>> index 0d735d5c2b35..942345548bc3 100644
>>> --- a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
>>> +++ b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
>>> @@ -126,7 +126,7 @@ static int i915_ttm_buddy_man_alloc(struct 
>>> ttm_resource_manager *man,
>>>       return 0;
>>>     err_free_blocks:
>>> -    drm_buddy_free_list(mm, &bman_res->blocks);
>>> +    drm_buddy_free_list(mm, &bman_res->blocks, 0);
>>>       mutex_unlock(&bman->lock);
>>>   err_free_res:
>>>       ttm_resource_fini(man, &bman_res->base);
>>> @@ -141,7 +141,7 @@ static void i915_ttm_buddy_man_free(struct 
>>> ttm_resource_manager *man,
>>>       struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
>>>         mutex_lock(&bman->lock);
>>> -    drm_buddy_free_list(&bman->mm, &bman_res->blocks);
>>> +    drm_buddy_free_list(&bman->mm, &bman_res->blocks, 0);
>>>       bman->visible_avail += bman_res->used_visible_size;
>>>       mutex_unlock(&bman->lock);
>>>   @@ -345,7 +345,7 @@ int i915_ttm_buddy_man_fini(struct ttm_device 
>>> *bdev, unsigned int type)
>>>       ttm_set_driver_manager(bdev, type, NULL);
>>>         mutex_lock(&bman->lock);
>>> -    drm_buddy_free_list(mm, &bman->reserved);
>>> +    drm_buddy_free_list(mm, &bman->reserved, 0);
>>>       drm_buddy_fini(mm);
>>>       bman->visible_avail += bman->visible_reserved;
>>>       WARN_ON_ONCE(bman->visible_avail != bman->visible_size);
>>> diff --git a/drivers/gpu/drm/tests/drm_buddy_test.c 
>>> b/drivers/gpu/drm/tests/drm_buddy_test.c
>>> index 2f32fb2f12e7..454ad9952f56 100644
>>> --- a/drivers/gpu/drm/tests/drm_buddy_test.c
>>> +++ b/drivers/gpu/drm/tests/drm_buddy_test.c
>>> @@ -64,7 +64,7 @@ static void drm_test_buddy_alloc_contiguous(struct 
>>> kunit *test)
>>> DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>>>                      "buddy_alloc didn't error size=%u\n", 3 * ps);
>>>   -    drm_buddy_free_list(&mm, &middle);
>>> +    drm_buddy_free_list(&mm, &middle, 0);
>>>       KUNIT_ASSERT_TRUE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, 
>>> mm_size,
>>>                                  3 * ps, ps, &allocated,
>>> DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>>> @@ -74,7 +74,7 @@ static void drm_test_buddy_alloc_contiguous(struct 
>>> kunit *test)
>>> DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>>>                      "buddy_alloc didn't error size=%u\n", 2 * ps);
>>>   -    drm_buddy_free_list(&mm, &right);
>>> +    drm_buddy_free_list(&mm, &right, 0);
>>>       KUNIT_ASSERT_TRUE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, 
>>> mm_size,
>>>                                  3 * ps, ps, &allocated,
>>> DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>>> @@ -89,7 +89,7 @@ static void drm_test_buddy_alloc_contiguous(struct 
>>> kunit *test)
>>> DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>>>                      "buddy_alloc hit an error size=%u\n", 2 * ps);
>>>   -    drm_buddy_free_list(&mm, &left);
>>> +    drm_buddy_free_list(&mm, &left, 0);
>>>       KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, 
>>> mm_size,
>>>                                   3 * ps, ps, &allocated,
>>> DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>>> @@ -101,7 +101,7 @@ static void 
>>> drm_test_buddy_alloc_contiguous(struct kunit *test)
>>>         KUNIT_ASSERT_EQ(test, total, ps * 2 + ps * 3);
>>>   -    drm_buddy_free_list(&mm, &allocated);
>>> +    drm_buddy_free_list(&mm, &allocated, 0);
>>>       drm_buddy_fini(&mm);
>>>   }
>>>   @@ -170,7 +170,7 @@ static void 
>>> drm_test_buddy_alloc_pathological(struct kunit *test)
>>>                                 top, max_order);
>>>       }
>>>   -    drm_buddy_free_list(&mm, &holes);
>>> +    drm_buddy_free_list(&mm, &holes, 0);
>>>         /* Nothing larger than blocks of chunk_size now available */
>>>       for (order = 1; order <= max_order; order++) {
>>> @@ -182,7 +182,7 @@ static void 
>>> drm_test_buddy_alloc_pathological(struct kunit *test)
>>>       }
>>>         list_splice_tail(&holes, &blocks);
>>> -    drm_buddy_free_list(&mm, &blocks);
>>> +    drm_buddy_free_list(&mm, &blocks, 0);
>>>       drm_buddy_fini(&mm);
>>>   }
>>>   @@ -277,7 +277,7 @@ static void 
>>> drm_test_buddy_alloc_pessimistic(struct kunit *test)
>>>         list_del(&block->link);
>>>       drm_buddy_free_block(&mm, block);
>>> -    drm_buddy_free_list(&mm, &blocks);
>>> +    drm_buddy_free_list(&mm, &blocks, 0);
>>>       drm_buddy_fini(&mm);
>>>   }
>>>   @@ -323,7 +323,7 @@ static void 
>>> drm_test_buddy_alloc_optimistic(struct kunit *test)
>>>                                  size, size, &tmp, flags),
>>>                             "buddy_alloc unexpectedly succeeded, it 
>>> should be full!");
>>>   -    drm_buddy_free_list(&mm, &blocks);
>>> +    drm_buddy_free_list(&mm, &blocks, 0);
>>>       drm_buddy_fini(&mm);
>>>   }
>>>   @@ -358,7 +358,7 @@ static void drm_test_buddy_alloc_limit(struct 
>>> kunit *test)
>>>                           drm_buddy_block_size(&mm, block),
>>>                           BIT_ULL(mm.max_order) * PAGE_SIZE);
>>>   -    drm_buddy_free_list(&mm, &allocated);
>>> +    drm_buddy_free_list(&mm, &allocated, 0);
>>>       drm_buddy_fini(&mm);
>>>   }
>>>   diff --git a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c 
>>> b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
>>> index 115ec745e502..1ad678b62c4a 100644
>>> --- a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
>>> +++ b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
>>> @@ -196,7 +196,7 @@ static int xe_ttm_vram_mgr_new(struct 
>>> ttm_resource_manager *man,
>>>       return 0;
>>>     error_free_blocks:
>>> -    drm_buddy_free_list(mm, &vres->blocks);
>>> +    drm_buddy_free_list(mm, &vres->blocks, 0);
>>>       mutex_unlock(&mgr->lock);
>>>   error_fini:
>>>       ttm_resource_fini(man, &vres->base);
>>> @@ -214,7 +214,7 @@ static void xe_ttm_vram_mgr_del(struct 
>>> ttm_resource_manager *man,
>>>       struct drm_buddy *mm = &mgr->mm;
>>>         mutex_lock(&mgr->lock);
>>> -    drm_buddy_free_list(mm, &vres->blocks);
>>> +    drm_buddy_free_list(mm, &vres->blocks, 0);
>>>       mgr->visible_avail += vres->used_visible_size;
>>>       mutex_unlock(&mgr->lock);
>>>   diff --git a/include/drm/drm_buddy.h b/include/drm/drm_buddy.h
>>> index a5b39fc01003..82570f77e817 100644
>>> --- a/include/drm/drm_buddy.h
>>> +++ b/include/drm/drm_buddy.h
>>> @@ -25,6 +25,8 @@
>>>   #define DRM_BUDDY_RANGE_ALLOCATION        BIT(0)
>>>   #define DRM_BUDDY_TOPDOWN_ALLOCATION        BIT(1)
>>>   #define DRM_BUDDY_CONTIGUOUS_ALLOCATION        BIT(2)
>>> +#define DRM_BUDDY_CLEAR_ALLOCATION        BIT(3)
>>> +#define DRM_BUDDY_CLEARED            BIT(4)
>>>     struct drm_buddy_block {
>>>   #define DRM_BUDDY_HEADER_OFFSET GENMASK_ULL(63, 12)
>>> @@ -32,8 +34,9 @@ struct drm_buddy_block {
>>>   #define   DRM_BUDDY_ALLOCATED       (1 << 10)
>>>   #define   DRM_BUDDY_FREE       (2 << 10)
>>>   #define   DRM_BUDDY_SPLIT       (3 << 10)
>>> +#define DRM_BUDDY_HEADER_CLEAR  GENMASK_ULL(9, 9)
>>>   /* Free to be used, if needed in the future */
>>> -#define DRM_BUDDY_HEADER_UNUSED GENMASK_ULL(9, 6)
>>> +#define DRM_BUDDY_HEADER_UNUSED GENMASK_ULL(8, 6)
>>>   #define DRM_BUDDY_HEADER_ORDER  GENMASK_ULL(5, 0)
>>>       u64 header;
>>>   @@ -86,6 +89,7 @@ struct drm_buddy {
>>>       u64 chunk_size;
>>>       u64 size;
>>>       u64 avail;
>>> +    u64 clear_avail;
>>>   };
>>>     static inline u64
>>> @@ -112,6 +116,12 @@ drm_buddy_block_is_allocated(struct 
>>> drm_buddy_block *block)
>>>       return drm_buddy_block_state(block) == DRM_BUDDY_ALLOCATED;
>>>   }
>>>   +static inline bool
>>> +drm_buddy_block_is_clear(struct drm_buddy_block *block)
>>> +{
>>> +    return block->header & DRM_BUDDY_HEADER_CLEAR;
>>> +}
>>> +
>>>   static inline bool
>>>   drm_buddy_block_is_free(struct drm_buddy_block *block)
>>>   {
>>> @@ -150,7 +160,9 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>>>     void drm_buddy_free_block(struct drm_buddy *mm, struct 
>>> drm_buddy_block *block);
>>>   -void drm_buddy_free_list(struct drm_buddy *mm, struct list_head 
>>> *objects);
>>> +void drm_buddy_free_list(struct drm_buddy *mm,
>>> +             struct list_head *objects,
>>> +             unsigned int flags);
>>>     void drm_buddy_print(struct drm_buddy *mm, struct drm_printer *p);
>>>   void drm_buddy_block_print(struct drm_buddy *mm,
>

Paneer Selvam, Arunpravin April 1, 2024, 11:07 a.m. UTC | #5

Hi Matthew,

On 3/28/2024 10:18 PM, Matthew Auld wrote:
> On 28/03/2024 16:07, Paneer Selvam, Arunpravin wrote:
>> Hi Matthew,
>>
>> On 3/26/2024 11:39 PM, Matthew Auld wrote:
>>> On 18/03/2024 21:40, Arunpravin Paneer Selvam wrote:
>>>> - Add tracking clear page feature.
>>>>
>>>> - Driver should enable the DRM_BUDDY_CLEARED flag if it
>>>>    successfully clears the blocks in the free path. On the otherhand,
>>>>    DRM buddy marks each block as cleared.
>>>>
>>>> - Track the available cleared pages size
>>>>
>>>> - If driver requests cleared memory we prefer cleared memory
>>>>    but fallback to uncleared if we can't find the cleared blocks.
>>>>    when driver requests uncleared memory we try to use uncleared but
>>>>    fallback to cleared memory if necessary.
>>>>
>>>> - When a block gets freed we clear it and mark the freed block as 
>>>> cleared,
>>>>    when there are buddies which are cleared as well we can merge them.
>>>>    Otherwise, we prefer to keep the blocks as separated.
>>>>
>>>> - Add a function to support defragmentation.
>>>>
>>>> v1:
>>>>    - Depends on the flag check DRM_BUDDY_CLEARED, enable the block as
>>>>      cleared. Else, reset the clear flag for each block in the 
>>>> list(Christian)
>>>>    - For merging the 2 cleared blocks compare as below,
>>>>      drm_buddy_is_clear(block) != drm_buddy_is_clear(buddy)(Christian)
>>>>    - Defragment the memory beginning from min_order
>>>>      till the required memory space is available.
>>>>
>>>> v2: (Matthew)
>>>>    - Add a wrapper drm_buddy_free_list_internal for the freeing of 
>>>> blocks
>>>>      operation within drm buddy.
>>>>    - Write a macro block_incompatible() to allocate the required 
>>>> blocks.
>>>>    - Update the xe driver for the drm_buddy_free_list change in 
>>>> arguments.
>>>>    - add a warning if the two blocks are incompatible on
>>>>      defragmentation
>>>>    - call full defragmentation in the fini() function
>>>>    - place a condition to test if min_order is equal to 0
>>>>    - replace the list with safe_reverse() variant as we might
>>>>      remove the block from the list.
>>>>
>>>> v3:
>>>>    - fix Gitlab user reported lockup issue.
>>>>    - Keep DRM_BUDDY_HEADER_CLEAR define sorted(Matthew)
>>>>    - modify to pass the root order instead max_order in fini()
>>>>      function(Matthew)
>>>>    - change bool 1 to true(Matthew)
>>>>    - add check if min_block_size is power of 2(Matthew)
>>>>    - modify the min_block_size datatype to u64(Matthew)
>>>>
>>>> v4:
>>>>    - rename the function drm_buddy_defrag with __force_merge.
>>>>    - Include __force_merge directly in drm buddy file and remove
>>>>      the defrag use in amdgpu driver.
>>>>    - Remove list_empty() check(Matthew)
>>>>    - Remove unnecessary space, headers and placement of new 
>>>> variables(Matthew)
>>>>    - Add a unit test case(Matthew)
>>>>
>>>> Signed-off-by: Arunpravin Paneer Selvam 
>>>> <[e-mail]>
>>>> Signed-off-by: Matthew Auld <[e-mail]>
>>>> Suggested-by: Christian König <[e-mail]>
>>>> Suggested-by: Matthew Auld <[e-mail]>
>>>> ---
>>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c  |   6 +-
>>>>   drivers/gpu/drm/drm_buddy.c                   | 427 
>>>> ++++++++++++++----
>>>>   drivers/gpu/drm/i915/i915_ttm_buddy_manager.c |   6 +-
>>>>   drivers/gpu/drm/tests/drm_buddy_test.c        |  18 +-
>>>>   drivers/gpu/drm/xe/xe_ttm_vram_mgr.c          |   4 +-
>>>>   include/drm/drm_buddy.h                       |  16 +-
>>>>   6 files changed, 360 insertions(+), 117 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c 
>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>>>> index 8db880244324..c0c851409241 100644
>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>>>> @@ -571,7 +571,7 @@ static int amdgpu_vram_mgr_new(struct 
>>>> ttm_resource_manager *man,
>>>>       return 0;
>>>>     error_free_blocks:
>>>> -    drm_buddy_free_list(mm, &vres->blocks);
>>>> +    drm_buddy_free_list(mm, &vres->blocks, 0);
>>>>       mutex_unlock(&mgr->lock);
>>>>   error_fini:
>>>>       ttm_resource_fini(man, &vres->base);
>>>> @@ -604,7 +604,7 @@ static void amdgpu_vram_mgr_del(struct 
>>>> ttm_resource_manager *man,
>>>>         amdgpu_vram_mgr_do_reserve(man);
>>>>   -    drm_buddy_free_list(mm, &vres->blocks);
>>>> +    drm_buddy_free_list(mm, &vres->blocks, 0);
>>>>       mutex_unlock(&mgr->lock);
>>>>         atomic64_sub(vis_usage, &mgr->vis_usage);
>>>> @@ -912,7 +912,7 @@ void amdgpu_vram_mgr_fini(struct amdgpu_device 
>>>> *adev)
>>>>           kfree(rsv);
>>>>         list_for_each_entry_safe(rsv, temp, &mgr->reserved_pages, 
>>>> blocks) {
>>>> -        drm_buddy_free_list(&mgr->mm, &rsv->allocated);
>>>> +        drm_buddy_free_list(&mgr->mm, &rsv->allocated, 0);
>>>>           kfree(rsv);
>>>>       }
>>>>       if (!adev->gmc.is_app_apu)
>>>> diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c
>>>> index c4222b886db7..625a30a6b855 100644
>>>> --- a/drivers/gpu/drm/drm_buddy.c
>>>> +++ b/drivers/gpu/drm/drm_buddy.c
>>>> @@ -38,8 +38,8 @@ static void drm_block_free(struct drm_buddy *mm,
>>>>       kmem_cache_free(slab_blocks, block);
>>>>   }
>>>>   -static void list_insert_sorted(struct drm_buddy *mm,
>>>> -                   struct drm_buddy_block *block)
>>>> +static void list_insert(struct drm_buddy *mm,
>>>> +            struct drm_buddy_block *block)
>>>>   {
>>>>       struct drm_buddy_block *node;
>>>>       struct list_head *head;
>>>> @@ -57,6 +57,16 @@ static void list_insert_sorted(struct drm_buddy 
>>>> *mm,
>>>>       __list_add(&block->link, node->link.prev, &node->link);
>>>>   }
>>>>   +static void clear_reset(struct drm_buddy_block *block)
>>>> +{
>>>> +    block->header &= ~DRM_BUDDY_HEADER_CLEAR;
>>>> +}
>>>> +
>>>> +static void mark_cleared(struct drm_buddy_block *block)
>>>> +{
>>>> +    block->header |= DRM_BUDDY_HEADER_CLEAR;
>>>> +}
>>>> +
>>>>   static void mark_allocated(struct drm_buddy_block *block)
>>>>   {
>>>>       block->header &= ~DRM_BUDDY_HEADER_STATE;
>>>> @@ -71,7 +81,7 @@ static void mark_free(struct drm_buddy *mm,
>>>>       block->header &= ~DRM_BUDDY_HEADER_STATE;
>>>>       block->header |= DRM_BUDDY_FREE;
>>>>   -    list_insert_sorted(mm, block);
>>>> +    list_insert(mm, block);
>>>>   }
>>>>     static void mark_split(struct drm_buddy_block *block)
>>>> @@ -82,6 +92,114 @@ static void mark_split(struct drm_buddy_block 
>>>> *block)
>>>>       list_del(&block->link);
>>>>   }
>>>>   +static struct drm_buddy_block *
>>>> +__get_buddy(struct drm_buddy_block *block)
>>>> +{
>>>> +    struct drm_buddy_block *parent;
>>>> +
>>>> +    parent = block->parent;
>>>> +    if (!parent)
>>>> +        return NULL;
>>>> +
>>>> +    if (parent->left == block)
>>>> +        return parent->right;
>>>> +
>>>> +    return parent->left;
>>>> +}
>>>> +
>>>> +static unsigned int __drm_buddy_free(struct drm_buddy *mm,
>>>> +                     struct drm_buddy_block *block,
>>>> +                     bool force_merge)
>>>> +{
>>>> +    struct drm_buddy_block *parent;
>>>> +    unsigned int order;
>>>> +
>>>> +    while ((parent = block->parent)) {
>>>> +        struct drm_buddy_block *buddy;
>>>> +
>>>> +        buddy = __get_buddy(block);
>>>> +
>>>> +        if (!drm_buddy_block_is_free(buddy))
>>>> +            break;
>>>> +
>>>> +        if (!force_merge) {
>>>> +            /**
>>>
>>> Not really valid kernel-doc AFAIK. I think drop the extra *. Below 
>>> also.
>>>
>>>> +             * Check the block and its buddy clear state and exit
>>>> +             * the loop if they both have the dissimilar state.
>>>> +             */
>>>> +            if (drm_buddy_block_is_clear(block) !=
>>>> +                drm_buddy_block_is_clear(buddy))
>>>> +                break;
>>>> +
>>>> +            if (drm_buddy_block_is_clear(block))
>>>> +                mark_cleared(parent);
>>>> +        }
>>>> +
>>>> +        list_del(&buddy->link);
>>>> +        if (force_merge && drm_buddy_block_is_clear(buddy))
>>>> +            mm->clear_avail -= drm_buddy_block_size(mm, buddy);
>>>> +
>>>> +        drm_block_free(mm, block);
>>>> +        drm_block_free(mm, buddy);
>>>> +
>>>> +        block = parent;
>>>> +    }
>>>> +
>>>> +    order = drm_buddy_block_order(block);
>>>> +    mark_free(mm, block);
>>>> +
>>>> +    return order;
>>>> +}
>>>> +
>>>> +static int __force_merge(struct drm_buddy *mm,
>>>> +             unsigned int min_order)
>>>> +{
>>>> +    unsigned int order;
>>>> +    int i;
>>>> +
>>>> +    if (!min_order)
>>>> +        return -ENOMEM;
>>>> +
>>>> +    if (min_order > mm->max_order)
>>>> +        return -EINVAL;
>>>> +
>>>> +    for (i = min_order - 1; i >= 0; i--) {
>>>> +        struct drm_buddy_block *block, *prev;
>>>> +
>>>> +        list_for_each_entry_safe_reverse(block, prev, 
>>>> &mm->free_list[i], link) {
>>>> +            struct drm_buddy_block *buddy;
>>>> +
>>>> +            if (!block->parent)
>>>> +                continue;
>>>> +
>>>> +            buddy = __get_buddy(block);
>>>> +            if (!drm_buddy_block_is_free(buddy))
>>>> +                continue;
>>>> +
>>>> +            WARN_ON(drm_buddy_block_is_clear(block) ==
>>>> +                drm_buddy_block_is_clear(buddy));
>>>> +
>>>> +            /**
>>>> +             * If the prev block is same as buddy, don't access the
>>>> +             * block in the next iteration as we would free the
>>>> +             * buddy block as part of the free function.
>>>> +             */
>>>> +            if (prev == buddy)
>>>> +                prev = list_prev_entry(prev, link);
>>>> +
>>>> +            list_del(&block->link);
>>>> +            if (drm_buddy_block_is_clear(block))
>>>> +                mm->clear_avail -= drm_buddy_block_size(mm, block);
>>>> +
>>>> +            order = __drm_buddy_free(mm, block, true);
>>>> +            if (order >= min_order)
>>>> +                return 0;
>>>> +        }
>>>> +    }
>>>> +
>>>> +    return -ENOMEM;
>>>> +}
>>>> +
>>>>   /**
>>>>    * drm_buddy_init - init memory manager
>>>>    *
>>>> @@ -137,7 +255,7 @@ int drm_buddy_init(struct drm_buddy *mm, u64 
>>>> size, u64 chunk_size)
>>>>       offset = 0;
>>>>       i = 0;
>>>>   -    /*
>>>> +    /**
>>>>        * Split into power-of-two blocks, in case we are given a 
>>>> size that is
>>>>        * not itself a power-of-two.
>>>>        */
>>>> @@ -186,11 +304,21 @@ EXPORT_SYMBOL(drm_buddy_init);
>>>>    */
>>>>   void drm_buddy_fini(struct drm_buddy *mm)
>>>>   {
>>>> +    u64 root_size, size;
>>>> +    unsigned int order;
>>>>       int i;
>>>>   +    size = mm->size;
>>>> +
>>>>       for (i = 0; i < mm->n_roots; ++i) {
>>>> +        order = ilog2(size) - ilog2(mm->chunk_size);
>>>> +        __force_merge(mm, order);
>>>> +
>>>> WARN_ON(!drm_buddy_block_is_free(mm->roots[i]));
>>>>           drm_block_free(mm, mm->roots[i]);
>>>> +
>>>> +        root_size = mm->chunk_size << order;
>>>> +        size -= root_size;
>>>>       }
>>>>         WARN_ON(mm->avail != mm->size);
>>>> @@ -223,26 +351,17 @@ static int split_block(struct drm_buddy *mm,
>>>>       mark_free(mm, block->left);
>>>>       mark_free(mm, block->right);
>>>>   +    if (drm_buddy_block_is_clear(block)) {
>>>> +        mark_cleared(block->left);
>>>> +        mark_cleared(block->right);
>>>> +        clear_reset(block);
>>>> +    }
>>>> +
>>>>       mark_split(block);
>>>>         return 0;
>>>>   }
>>>>   -static struct drm_buddy_block *
>>>> -__get_buddy(struct drm_buddy_block *block)
>>>> -{
>>>> -    struct drm_buddy_block *parent;
>>>> -
>>>> -    parent = block->parent;
>>>> -    if (!parent)
>>>> -        return NULL;
>>>> -
>>>> -    if (parent->left == block)
>>>> -        return parent->right;
>>>> -
>>>> -    return parent->left;
>>>> -}
>>>> -
>>>>   /**
>>>>    * drm_get_buddy - get buddy address
>>>>    *
>>>> @@ -260,30 +379,6 @@ drm_get_buddy(struct drm_buddy_block *block)
>>>>   }
>>>>   EXPORT_SYMBOL(drm_get_buddy);
>>>>   -static void __drm_buddy_free(struct drm_buddy *mm,
>>>> -                 struct drm_buddy_block *block)
>>>> -{
>>>> -    struct drm_buddy_block *parent;
>>>> -
>>>> -    while ((parent = block->parent)) {
>>>> -        struct drm_buddy_block *buddy;
>>>> -
>>>> -        buddy = __get_buddy(block);
>>>> -
>>>> -        if (!drm_buddy_block_is_free(buddy))
>>>> -            break;
>>>> -
>>>> -        list_del(&buddy->link);
>>>> -
>>>> -        drm_block_free(mm, block);
>>>> -        drm_block_free(mm, buddy);
>>>> -
>>>> -        block = parent;
>>>> -    }
>>>> -
>>>> -    mark_free(mm, block);
>>>> -}
>>>> -
>>>>   /**
>>>>    * drm_buddy_free_block - free a block
>>>>    *
>>>> @@ -295,26 +390,59 @@ void drm_buddy_free_block(struct drm_buddy *mm,
>>>>   {
>>>>       BUG_ON(!drm_buddy_block_is_allocated(block));
>>>>       mm->avail += drm_buddy_block_size(mm, block);
>>>> -    __drm_buddy_free(mm, block);
>>>> +    if (drm_buddy_block_is_clear(block))
>>>> +        mm->clear_avail += drm_buddy_block_size(mm, block);
>>>> +
>>>> +    __drm_buddy_free(mm, block, false);
>>>>   }
>>>>   EXPORT_SYMBOL(drm_buddy_free_block);
>>>>   -/**
>>>> - * drm_buddy_free_list - free blocks
>>>> - *
>>>> - * @mm: DRM buddy manager
>>>> - * @objects: input list head to free blocks
>>>> - */
>>>> -void drm_buddy_free_list(struct drm_buddy *mm, struct list_head 
>>>> *objects)
>>>> +static void __drm_buddy_free_list(struct drm_buddy *mm,
>>>> +                  struct list_head *objects,
>>>> +                  bool mark_clear,
>>>> +                  bool mark_dirty)
>>>>   {
>>>>       struct drm_buddy_block *block, *on;
>>>>   +    WARN_ON(mark_dirty && mark_clear);
>>>> +
>>>>       list_for_each_entry_safe(block, on, objects, link) {
>>>> +        if (mark_clear)
>>>> +            mark_cleared(block);
>>>> +        else if (mark_dirty)
>>>> +            clear_reset(block);
>>>>           drm_buddy_free_block(mm, block);
>>>>           cond_resched();
>>>>       }
>>>>       INIT_LIST_HEAD(objects);
>>>>   }
>>>> +
>>>> +static void drm_buddy_free_list_internal(struct drm_buddy *mm,
>>>> +                     struct list_head *objects)
>>>> +{
>>>> +    /**
>>>> +     * Don't touch the clear/dirty bit, since allocation is still 
>>>> internal
>>>> +     * at this point. For example we might have just failed part 
>>>> of the
>>>> +     * allocation.
>>>> +     */
>>>> +    __drm_buddy_free_list(mm, objects, false, false);
>>>> +}
>>>> +
>>>> +/**
>>>> + * drm_buddy_free_list - free blocks
>>>> + *
>>>> + * @mm: DRM buddy manager
>>>> + * @objects: input list head to free blocks
>>>> + * @flags: optional flags like DRM_BUDDY_CLEARED
>>>> + */
>>>> +void drm_buddy_free_list(struct drm_buddy *mm,
>>>> +             struct list_head *objects,
>>>> +             unsigned int flags)
>>>> +{
>>>> +    bool mark_clear = flags & DRM_BUDDY_CLEARED;
>>>> +
>>>> +    __drm_buddy_free_list(mm, objects, mark_clear, !mark_clear);
>>>> +}
>>>>   EXPORT_SYMBOL(drm_buddy_free_list);
>>>>     static inline bool overlaps(u64 s1, u64 e1, u64 s2, u64 e2)
>>>> @@ -327,10 +455,19 @@ static inline bool contains(u64 s1, u64 e1, 
>>>> u64 s2, u64 e2)
>>>>       return s1 <= s2 && e1 >= e2;
>>>>   }
>>>>   +static bool block_incompatible(struct drm_buddy_block *block, 
>>>> unsigned int flags)
>>>> +{
>>>> +    bool needs_clear = flags & DRM_BUDDY_CLEAR_ALLOCATION;
>>>> +
>>>> +    return needs_clear != drm_buddy_block_is_clear(block);
>>>> +}
>>>> +
>>>>   static struct drm_buddy_block *
>>>> -alloc_range_bias(struct drm_buddy *mm,
>>>> -         u64 start, u64 end,
>>>> -         unsigned int order)
>>>> +__alloc_range_bias(struct drm_buddy *mm,
>>>> +           u64 start, u64 end,
>>>> +           unsigned int order,
>>>> +           unsigned long flags,
>>>> +           bool fallback)
>>>>   {
>>>>       struct drm_buddy_block *block;
>>>>       struct drm_buddy_block *buddy;
>>>> @@ -369,7 +506,10 @@ alloc_range_bias(struct drm_buddy *mm,
>>>>             if (contains(start, end, block_start, block_end) &&
>>>>               order == drm_buddy_block_order(block)) {
>>>> -            /*
>>>> +            if (!fallback && block_incompatible(block, flags))
>>>> +                continue;
>>>> +
>>>> +            /**
>>>>                * Find the free block within the range.
>>>>                */
>>>>               if (drm_buddy_block_is_free(block))
>>>> @@ -391,7 +531,7 @@ alloc_range_bias(struct drm_buddy *mm,
>>>>       return ERR_PTR(-ENOSPC);
>>>>     err_undo:
>>>> -    /*
>>>> +    /**
>>>>        * We really don't want to leave around a bunch of split 
>>>> blocks, since
>>>>        * bigger is better, so make sure we merge everything back 
>>>> before we
>>>>        * free the allocated blocks.
>>>> @@ -400,30 +540,57 @@ alloc_range_bias(struct drm_buddy *mm,
>>>>       if (buddy &&
>>>>           (drm_buddy_block_is_free(block) &&
>>>>            drm_buddy_block_is_free(buddy)))
>>>> -        __drm_buddy_free(mm, block);
>>>> +        __drm_buddy_free(mm, block, false);
>>>>       return ERR_PTR(err);
>>>>   }
>>>>     static struct drm_buddy_block *
>>>> -get_maxblock(struct drm_buddy *mm, unsigned int order)
>>>> +__drm_buddy_alloc_range_bias(struct drm_buddy *mm,
>>>> +                 u64 start, u64 end,
>>>> +                 unsigned int order,
>>>> +                 unsigned long flags)
>>>> +{
>>>> +    struct drm_buddy_block *block;
>>>> +    bool fallback = false;
>>>> +
>>>> +    block = __alloc_range_bias(mm, start, end, order,
>>>> +                   flags, fallback);
>>>> +    if (IS_ERR(block) && mm->clear_avail)
>>>> +        return __alloc_range_bias(mm, start, end, order,
>>>> +                      flags, !fallback);
>>>> +
>>>> +    return block;
>>>> +}
>>>> +
>>>> +static struct drm_buddy_block *
>>>> +get_maxblock(struct drm_buddy *mm, unsigned int order,
>>>> +         unsigned long flags)
>>>>   {
>>>> -    struct drm_buddy_block *max_block = NULL, *node;
>>>> +    struct drm_buddy_block *max_block = NULL, *block = NULL;
>>>>       unsigned int i;
>>>>         for (i = order; i <= mm->max_order; ++i) {
>>>> -        if (!list_empty(&mm->free_list[i])) {
>>>> -            node = list_last_entry(&mm->free_list[i],
>>>> -                           struct drm_buddy_block,
>>>> -                           link);
>>>> -            if (!max_block) {
>>>> -                max_block = node;
>>>> +        struct drm_buddy_block *tmp_block;
>>>> +
>>>> +        list_for_each_entry_reverse(tmp_block, &mm->free_list[i], 
>>>> link) {
>>>> +            if (block_incompatible(tmp_block, flags))
>>>>                   continue;
>>>> -            }
>>>>   -            if (drm_buddy_block_offset(node) >
>>>> -                drm_buddy_block_offset(max_block)) {
>>>> -                max_block = node;
>>>> -            }
>>>> +            block = tmp_block;
>>>> +            break;
>>>> +        }
>>>> +
>>>> +        if (!block)
>>>> +            continue;
>>>> +
>>>> +        if (!max_block) {
>>>> +            max_block = block;
>>>> +            continue;
>>>> +        }
>>>> +
>>>> +        if (drm_buddy_block_offset(block) >
>>>> +            drm_buddy_block_offset(max_block)) {
>>>> +            max_block = block;
>>>>           }
>>>>       }
>>>>   @@ -440,11 +607,29 @@ alloc_from_freelist(struct drm_buddy *mm,
>>>>       int err;
>>>>         if (flags & DRM_BUDDY_TOPDOWN_ALLOCATION) {
>>>> -        block = get_maxblock(mm, order);
>>>> +        block = get_maxblock(mm, order, flags);
>>>>           if (block)
>>>>               /* Store the obtained block order */
>>>>               tmp = drm_buddy_block_order(block);
>>>>       } else {
>>>> +        for (tmp = order; tmp <= mm->max_order; ++tmp) {
>>>> +            struct drm_buddy_block *tmp_block;
>>>> +
>>>> +            list_for_each_entry_reverse(tmp_block, 
>>>> &mm->free_list[tmp], link) {
>>>> +                if (block_incompatible(tmp_block, flags))
>>>> +                    continue;
>>>> +
>>>> +                block = tmp_block;
>>>> +                break;
>>>> +            }
>>>> +
>>>> +            if (block)
>>>> +                break;
>>>> +        }
>>>> +    }
>>>> +
>>>> +    if (!block) {
>>>> +        /* Fallback method */
>>>>           for (tmp = order; tmp <= mm->max_order; ++tmp) {
>>>>               if (!list_empty(&mm->free_list[tmp])) {
>>>>                   block = list_last_entry(&mm->free_list[tmp],
>>>> @@ -454,10 +639,10 @@ alloc_from_freelist(struct drm_buddy *mm,
>>>>                       break;
>>>>               }
>>>>           }
>>>> -    }
>>>>   -    if (!block)
>>>> -        return ERR_PTR(-ENOSPC);
>>>> +        if (!block)
>>>> +            return ERR_PTR(-ENOSPC);
>>>> +    }
>>>>         BUG_ON(!drm_buddy_block_is_free(block));
>>>>   @@ -473,7 +658,7 @@ alloc_from_freelist(struct drm_buddy *mm,
>>>>     err_undo:
>>>>       if (tmp != order)
>>>> -        __drm_buddy_free(mm, block);
>>>> +        __drm_buddy_free(mm, block, false);
>>>>       return ERR_PTR(err);
>>>>   }
>>>>   @@ -524,6 +709,8 @@ static int __alloc_range(struct drm_buddy *mm,
>>>>               mark_allocated(block);
>>>>               total_allocated += drm_buddy_block_size(mm, block);
>>>>               mm->avail -= drm_buddy_block_size(mm, block);
>>>> +            if (drm_buddy_block_is_clear(block))
>>>> +                mm->clear_avail -= drm_buddy_block_size(mm, block);
>>>>               list_add_tail(&block->link, &allocated);
>>>>               continue;
>>>>           }
>>>> @@ -548,7 +735,7 @@ static int __alloc_range(struct drm_buddy *mm,
>>>>       return 0;
>>>>     err_undo:
>>>> -    /*
>>>> +    /**
>>>>        * We really don't want to leave around a bunch of split 
>>>> blocks, since
>>>>        * bigger is better, so make sure we merge everything back 
>>>> before we
>>>>        * free the allocated blocks.
>>>> @@ -557,14 +744,14 @@ static int __alloc_range(struct drm_buddy *mm,
>>>>       if (buddy &&
>>>>           (drm_buddy_block_is_free(block) &&
>>>>            drm_buddy_block_is_free(buddy)))
>>>> -        __drm_buddy_free(mm, block);
>>>> +        __drm_buddy_free(mm, block, false);
>>>>     err_free:
>>>>       if (err == -ENOSPC && total_allocated_on_err) {
>>>>           list_splice_tail(&allocated, blocks);
>>>>           *total_allocated_on_err = total_allocated;
>>>>       } else {
>>>> -        drm_buddy_free_list(mm, &allocated);
>>>> +        drm_buddy_free_list_internal(mm, &allocated);
>>>>       }
>>>>         return err;
>>>> @@ -630,11 +817,11 @@ static int __alloc_contig_try_harder(struct 
>>>> drm_buddy *mm,
>>>>               list_splice(&blocks_lhs, blocks);
>>>>               return 0;
>>>>           } else if (err != -ENOSPC) {
>>>> -            drm_buddy_free_list(mm, blocks);
>>>> +            drm_buddy_free_list_internal(mm, blocks);
>>>>               return err;
>>>>           }
>>>>           /* Free blocks for the next iteration */
>>>> -        drm_buddy_free_list(mm, blocks);
>>>> +        drm_buddy_free_list_internal(mm, blocks);
>>>>       }
>>>>         return -ENOSPC;
>>>> @@ -690,6 +877,8 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>>>>       list_del(&block->link);
>>>>       mark_free(mm, block);
>>>>       mm->avail += drm_buddy_block_size(mm, block);
>>>> +    if (drm_buddy_block_is_clear(block))
>>>> +        mm->clear_avail += drm_buddy_block_size(mm, block);
>>>>         /* Prevent recursively freeing this node */
>>>>       parent = block->parent;
>>>> @@ -701,6 +890,8 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>>>>       if (err) {
>>>>           mark_allocated(block);
>>>>           mm->avail -= drm_buddy_block_size(mm, block);
>>>> +        if (drm_buddy_block_is_clear(block))
>>>> +            mm->clear_avail -= drm_buddy_block_size(mm, block);
>>>>           list_add(&block->link, blocks);
>>>>       }
>>>>   @@ -709,13 +900,28 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>>>>   }
>>>>   EXPORT_SYMBOL(drm_buddy_block_trim);
>>>>   +static struct drm_buddy_block *
>>>> +__drm_buddy_alloc_blocks(struct drm_buddy *mm,
>>>> +             u64 start, u64 end,
>>>> +             unsigned int order,
>>>> +             unsigned long flags)
>>>> +{
>>>> +    if (flags & DRM_BUDDY_RANGE_ALLOCATION)
>>>> +        /* Allocate traversing within the range */
>>>> +        return  __drm_buddy_alloc_range_bias(mm, start, end,
>>>> +                             order, flags);
>>>> +    else
>>>> +        /* Allocate from freelist */
>>>> +        return alloc_from_freelist(mm, order, flags);
>>>> +}
>>>> +
>>>>   /**
>>>>    * drm_buddy_alloc_blocks - allocate power-of-two blocks
>>>>    *
>>>>    * @mm: DRM buddy manager to allocate from
>>>>    * @start: start of the allowed range for this block
>>>>    * @end: end of the allowed range for this block
>>>> - * @size: size of the allocation
>>>> + * @size: size of the allocation in bytes
>>>>    * @min_block_size: alignment of the allocation
>>>>    * @blocks: output list head to add allocated blocks
>>>>    * @flags: DRM_BUDDY_*_ALLOCATION flags
>>>> @@ -761,8 +967,18 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>>>>           return -EINVAL;
>>>>         /* Actual range allocation */
>>>> -    if (start + size == end)
>>>> -        return __drm_buddy_alloc_range(mm, start, size, NULL, 
>>>> blocks);
>>>> +    if (start + size == end) {
>>>> +        err =  __drm_buddy_alloc_range(mm, start, size, NULL, 
>>>> blocks);
>>>> +        if (err) {
>>>> +            order = ilog2(size) - ilog2(mm->chunk_size);
>>>> +            if (mm->clear_avail && !__force_merge(mm, order))
>>>> +                return __drm_buddy_alloc_range(mm, start, size, 
>>>> NULL, blocks);
>>>
>>> That seems strange at a glance. With an actual range allocation like 
>>> with intitial fb or whatever it should just find all overlapping 
>>> pages, splitting down where needed on the edges. Not sure why 
>>> force_merge would factor in here?
>> In case of not merged (fragmentation due to dirty and clear pages 
>> split), if the memory request goes into that range, we might see the 
>> split blocks as not free and end up returning -ENOSPC.
>> I found this problem when I tried to allocate the max_order where the 
>> start + size == end and it ends up entering into this code block and 
>> it returns -ENOSPC as there is no force_merge call
>> and the requested range max order block seen as not free. And we have 
>> an another issue though if we use force_merge to defragment a 
>> specific ordered block, there is a less probability that
>> we merge back the required blocks in the specific range. For now, we 
>> can go ahead with no force merge support for actual range allocation 
>> if we are sure that we use this only for initial fb etc.
>
> Ah right, now I see. But AFAICT trouble is if we say allocate 8K range 
> at some specific offset, like above, which fails due to clear/dirty 
> split then calling force_merge(order(8K)) is not always going to help. 
> It will just force merge enough for 8K, but that might not be the 8K 
> at the offset we were looking for, so it still fails. I think perhaps 
> update the dfs in alloc_range to not bail when contains && split. Or I 
> think other option is to force merge the entire address space on err. 
> Other ideas?
For actual range allocation, if the min_block_size == mm->chunk_size, I 
think we can proceed with your first idea (i.e) update the dfs in 
alloc_range to not bail when contains && split.
For bias range allocation, we need to add range support to the 
force_merge, for instance we can just continue in the force_merge for 
loop if the contains(start, end, block_start, block_end) returns false.
Thoughts?

Thanks,
Arun.
>
>>
>> If there are no major concerns, can we push these patches?
>>
>> Regards,
>> Arun.
>>>> +
>>>> +            return err;
>>>> +        }
>>>> +
>>>> +        return err;
>>>> +    }
>>>>         original_size = size;
>>>>       original_min_size = min_block_size;
>>>> @@ -786,23 +1002,34 @@ int drm_buddy_alloc_blocks(struct drm_buddy 
>>>> *mm,
>>>>           BUG_ON(order < min_order);
>>>>             do {
>>>> -            if (flags & DRM_BUDDY_RANGE_ALLOCATION)
>>>> -                /* Allocate traversing within the range */
>>>> -                block = alloc_range_bias(mm, start, end, order);
>>>> -            else
>>>> -                /* Allocate from freelist */
>>>> -                block = alloc_from_freelist(mm, order, flags);
>>>> -
>>>> +            block = __drm_buddy_alloc_blocks(mm, start,
>>>> +                             end,
>>>> +                             order,
>>>> +                             flags);
>>>>               if (!IS_ERR(block))
>>>>                   break;
>>>>                 if (order-- == min_order) {
>>>> +                /**
>>>> +                 * Try allocation through force merge method
>>>> +                 */
>>>> +                if (mm->clear_avail && !__force_merge(mm, 
>>>> min_order)) {
>>>> +                    block = __drm_buddy_alloc_blocks(mm, start,
>>>> +                                     end,
>>>> +                                     min_order,
>>>> +                                     flags);
>>>> +                    if (!IS_ERR(block)) {
>>>> +                        order = min_order;
>>>> +                        break;
>>>> +                    }
>>>> +                }
>>>> +
>>>> +    ��           /**
>>>> +                 * Try contiguous block allocation through
>>>> +                 * try harder method.
>>>> +                 */
>>>>                   if (flags & DRM_BUDDY_CONTIGUOUS_ALLOCATION &&
>>>>                       !(flags & DRM_BUDDY_RANGE_ALLOCATION))
>>>> -                    /*
>>>> -                     * Try contiguous block allocation through
>>>> -                     * try harder method
>>>> -                     */
>>>>                       return __alloc_contig_try_harder(mm,
>>>>                                        original_size,
>>>>                                        original_min_size,
>>>> @@ -814,6 +1041,8 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>>>>             mark_allocated(block);
>>>>           mm->avail -= drm_buddy_block_size(mm, block);
>>>> +        if (drm_buddy_block_is_clear(block))
>>>> +            mm->clear_avail -= drm_buddy_block_size(mm, block);
>>>>           kmemleak_update_trace(block);
>>>>           list_add_tail(&block->link, &allocated);
>>>>   @@ -823,7 +1052,9 @@ int drm_buddy_alloc_blocks(struct drm_buddy 
>>>> *mm,
>>>>               break;
>>>>       } while (1);
>>>>   -    /* Trim the allocated block to the required size */
>>>> +    /**
>>>> +     * Trim the allocated block to the required size
>>>> +     */
>>>>       if (original_size != size) {
>>>>           struct list_head *trim_list;
>>>>           LIST_HEAD(temp);
>>>> @@ -852,7 +1083,7 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>>>>       return 0;
>>>>     err_free:
>>>> -    drm_buddy_free_list(mm, &allocated);
>>>> +    drm_buddy_free_list_internal(mm, &allocated);
>>>>       return err;
>>>>   }
>>>>   EXPORT_SYMBOL(drm_buddy_alloc_blocks);
>>>> @@ -885,8 +1116,8 @@ void drm_buddy_print(struct drm_buddy *mm, 
>>>> struct drm_printer *p)
>>>>   {
>>>>       int order;
>>>>   -    drm_printf(p, "chunk_size: %lluKiB, total: %lluMiB, free: 
>>>> %lluMiB\n",
>>>> -           mm->chunk_size >> 10, mm->size >> 20, mm->avail >> 20);
>>>> +    drm_printf(p, "chunk_size: %lluKiB, total: %lluMiB, free: 
>>>> %lluMiB, clear_free: %lluMiB\n",
>>>> +           mm->chunk_size >> 10, mm->size >> 20, mm->avail >> 20, 
>>>> mm->clear_avail >> 20);
>>>>         for (order = mm->max_order; order >= 0; order--) {
>>>>           struct drm_buddy_block *block;
>>>> diff --git a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c 
>>>> b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
>>>> index 0d735d5c2b35..942345548bc3 100644
>>>> --- a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
>>>> +++ b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
>>>> @@ -126,7 +126,7 @@ static int i915_ttm_buddy_man_alloc(struct 
>>>> ttm_resource_manager *man,
>>>>       return 0;
>>>>     err_free_blocks:
>>>> -    drm_buddy_free_list(mm, &bman_res->blocks);
>>>> +    drm_buddy_free_list(mm, &bman_res->blocks, 0);
>>>>       mutex_unlock(&bman->lock);
>>>>   err_free_res:
>>>>       ttm_resource_fini(man, &bman_res->base);
>>>> @@ -141,7 +141,7 @@ static void i915_ttm_buddy_man_free(struct 
>>>> ttm_resource_manager *man,
>>>>       struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
>>>>         mutex_lock(&bman->lock);
>>>> -    drm_buddy_free_list(&bman->mm, &bman_res->blocks);
>>>> +    drm_buddy_free_list(&bman->mm, &bman_res->blocks, 0);
>>>>       bman->visible_avail += bman_res->used_visible_size;
>>>>       mutex_unlock(&bman->lock);
>>>>   @@ -345,7 +345,7 @@ int i915_ttm_buddy_man_fini(struct ttm_device 
>>>> *bdev, unsigned int type)
>>>>       ttm_set_driver_manager(bdev, type, NULL);
>>>>         mutex_lock(&bman->lock);
>>>> -    drm_buddy_free_list(mm, &bman->reserved);
>>>> +    drm_buddy_free_list(mm, &bman->reserved, 0);
>>>>       drm_buddy_fini(mm);
>>>>       bman->visible_avail += bman->visible_reserved;
>>>>       WARN_ON_ONCE(bman->visible_avail != bman->visible_size);
>>>> diff --git a/drivers/gpu/drm/tests/drm_buddy_test.c 
>>>> b/drivers/gpu/drm/tests/drm_buddy_test.c
>>>> index 2f32fb2f12e7..454ad9952f56 100644
>>>> --- a/drivers/gpu/drm/tests/drm_buddy_test.c
>>>> +++ b/drivers/gpu/drm/tests/drm_buddy_test.c
>>>> @@ -64,7 +64,7 @@ static void 
>>>> drm_test_buddy_alloc_contiguous(struct kunit *test)
>>>> DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>>>>                      "buddy_alloc didn't error size=%u\n", 3 * ps);
>>>>   -    drm_buddy_free_list(&mm, &middle);
>>>> +    drm_buddy_free_list(&mm, &middle, 0);
>>>>       KUNIT_ASSERT_TRUE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, 
>>>> mm_size,
>>>>                                  3 * ps, ps, &allocated,
>>>> DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>>>> @@ -74,7 +74,7 @@ static void 
>>>> drm_test_buddy_alloc_contiguous(struct kunit *test)
>>>> DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>>>>                      "buddy_alloc didn't error size=%u\n", 2 * ps);
>>>>   -    drm_buddy_free_list(&mm, &right);
>>>> +    drm_buddy_free_list(&mm, &right, 0);
>>>>       KUNIT_ASSERT_TRUE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, 
>>>> mm_size,
>>>>                                  3 * ps, ps, &allocated,
>>>> DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>>>> @@ -89,7 +89,7 @@ static void 
>>>> drm_test_buddy_alloc_contiguous(struct kunit *test)
>>>> DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>>>>                      "buddy_alloc hit an error size=%u\n", 2 * ps);
>>>>   -    drm_buddy_free_list(&mm, &left);
>>>> +    drm_buddy_free_list(&mm, &left, 0);
>>>>       KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, 
>>>> mm_size,
>>>>                                   3 * ps, ps, &allocated,
>>>> DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>>>> @@ -101,7 +101,7 @@ static void 
>>>> drm_test_buddy_alloc_contiguous(struct kunit *test)
>>>>         KUNIT_ASSERT_EQ(test, total, ps * 2 + ps * 3);
>>>>   -    drm_buddy_free_list(&mm, &allocated);
>>>> +    drm_buddy_free_list(&mm, &allocated, 0);
>>>>       drm_buddy_fini(&mm);
>>>>   }
>>>>   @@ -170,7 +170,7 @@ static void 
>>>> drm_test_buddy_alloc_pathological(struct kunit *test)
>>>>                                 top, max_order);
>>>>       }
>>>>   -    drm_buddy_free_list(&mm, &holes);
>>>> +    drm_buddy_free_list(&mm, &holes, 0);
>>>>         /* Nothing larger than blocks of chunk_size now available */
>>>>       for (order = 1; order <= max_order; order++) {
>>>> @@ -182,7 +182,7 @@ static void 
>>>> drm_test_buddy_alloc_pathological(struct kunit *test)
>>>>       }
>>>>         list_splice_tail(&holes, &blocks);
>>>> -    drm_buddy_free_list(&mm, &blocks);
>>>> +    drm_buddy_free_list(&mm, &blocks, 0);
>>>>       drm_buddy_fini(&mm);
>>>>   }
>>>>   @@ -277,7 +277,7 @@ static void 
>>>> drm_test_buddy_alloc_pessimistic(struct kunit *test)
>>>>         list_del(&block->link);
>>>>       drm_buddy_free_block(&mm, block);
>>>> -    drm_buddy_free_list(&mm, &blocks);
>>>> +    drm_buddy_free_list(&mm, &blocks, 0);
>>>>       drm_buddy_fini(&mm);
>>>>   }
>>>>   @@ -323,7 +323,7 @@ static void 
>>>> drm_test_buddy_alloc_optimistic(struct kunit *test)
>>>>                                  size, size, &tmp, flags),
>>>>                             "buddy_alloc unexpectedly succeeded, it 
>>>> should be full!");
>>>>   -    drm_buddy_free_list(&mm, &blocks);
>>>> +    drm_buddy_free_list(&mm, &blocks, 0);
>>>>       drm_buddy_fini(&mm);
>>>>   }
>>>>   @@ -358,7 +358,7 @@ static void drm_test_buddy_alloc_limit(struct 
>>>> kunit *test)
>>>>                           drm_buddy_block_size(&mm, block),
>>>>                           BIT_ULL(mm.max_order) * PAGE_SIZE);
>>>>   -    drm_buddy_free_list(&mm, &allocated);
>>>> +    drm_buddy_free_list(&mm, &allocated, 0);
>>>>       drm_buddy_fini(&mm);
>>>>   }
>>>>   diff --git a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c 
>>>> b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
>>>> index 115ec745e502..1ad678b62c4a 100644
>>>> --- a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
>>>> +++ b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
>>>> @@ -196,7 +196,7 @@ static int xe_ttm_vram_mgr_new(struct 
>>>> ttm_resource_manager *man,
>>>>       return 0;
>>>>     error_free_blocks:
>>>> -    drm_buddy_free_list(mm, &vres->blocks);
>>>> +    drm_buddy_free_list(mm, &vres->blocks, 0);
>>>>       mutex_unlock(&mgr->lock);
>>>>   error_fini:
>>>>       ttm_resource_fini(man, &vres->base);
>>>> @@ -214,7 +214,7 @@ static void xe_ttm_vram_mgr_del(struct 
>>>> ttm_resource_manager *man,
>>>>       struct drm_buddy *mm = &mgr->mm;
>>>>         mutex_lock(&mgr->lock);
>>>> -    drm_buddy_free_list(mm, &vres->blocks);
>>>> +    drm_buddy_free_list(mm, &vres->blocks, 0);
>>>>       mgr->visible_avail += vres->used_visible_size;
>>>>       mutex_unlock(&mgr->lock);
>>>>   diff --git a/include/drm/drm_buddy.h b/include/drm/drm_buddy.h
>>>> index a5b39fc01003..82570f77e817 100644
>>>> --- a/include/drm/drm_buddy.h
>>>> +++ b/include/drm/drm_buddy.h
>>>> @@ -25,6 +25,8 @@
>>>>   #define DRM_BUDDY_RANGE_ALLOCATION        BIT(0)
>>>>   #define DRM_BUDDY_TOPDOWN_ALLOCATION        BIT(1)
>>>>   #define DRM_BUDDY_CONTIGUOUS_ALLOCATION        BIT(2)
>>>> +#define DRM_BUDDY_CLEAR_ALLOCATION        BIT(3)
>>>> +#define DRM_BUDDY_CLEARED            BIT(4)
>>>>     struct drm_buddy_block {
>>>>   #define DRM_BUDDY_HEADER_OFFSET GENMASK_ULL(63, 12)
>>>> @@ -32,8 +34,9 @@ struct drm_buddy_block {
>>>>   #define   DRM_BUDDY_ALLOCATED       (1 << 10)
>>>>   #define   DRM_BUDDY_FREE       (2 << 10)
>>>>   #define   DRM_BUDDY_SPLIT       (3 << 10)
>>>> +#define DRM_BUDDY_HEADER_CLEAR  GENMASK_ULL(9, 9)
>>>>   /* Free to be used, if needed in the future */
>>>> -#define DRM_BUDDY_HEADER_UNUSED GENMASK_ULL(9, 6)
>>>> +#define DRM_BUDDY_HEADER_UNUSED GENMASK_ULL(8, 6)
>>>>   #define DRM_BUDDY_HEADER_ORDER  GENMASK_ULL(5, 0)
>>>>       u64 header;
>>>>   @@ -86,6 +89,7 @@ struct drm_buddy {
>>>>       u64 chunk_size;
>>>>       u64 size;
>>>>       u64 avail;
>>>> +    u64 clear_avail;
>>>>   };
>>>>     static inline u64
>>>> @@ -112,6 +116,12 @@ drm_buddy_block_is_allocated(struct 
>>>> drm_buddy_block *block)
>>>>       return drm_buddy_block_state(block) == DRM_BUDDY_ALLOCATED;
>>>>   }
>>>>   +static inline bool
>>>> +drm_buddy_block_is_clear(struct drm_buddy_block *block)
>>>> +{
>>>> +    return block->header & DRM_BUDDY_HEADER_CLEAR;
>>>> +}
>>>> +
>>>>   static inline bool
>>>>   drm_buddy_block_is_free(struct drm_buddy_block *block)
>>>>   {
>>>> @@ -150,7 +160,9 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>>>>     void drm_buddy_free_block(struct drm_buddy *mm, struct 
>>>> drm_buddy_block *block);
>>>>   -void drm_buddy_free_list(struct drm_buddy *mm, struct list_head 
>>>> *objects);
>>>> +void drm_buddy_free_list(struct drm_buddy *mm,
>>>> +             struct list_head *objects,
>>>> +             unsigned int flags);
>>>>     void drm_buddy_print(struct drm_buddy *mm, struct drm_printer *p);
>>>>   void drm_buddy_block_print(struct drm_buddy *mm,
>>

Matthew Auld April 5, 2024, 3:43 p.m. UTC | #6

On 01/04/2024 12:07, Paneer Selvam, Arunpravin wrote:
> Hi Matthew,
> 
> On 3/28/2024 10:18 PM, Matthew Auld wrote:
>> On 28/03/2024 16:07, Paneer Selvam, Arunpravin wrote:
>>> Hi Matthew,
>>>
>>> On 3/26/2024 11:39 PM, Matthew Auld wrote:
>>>> On 18/03/2024 21:40, Arunpravin Paneer Selvam wrote:
>>>>> - Add tracking clear page feature.
>>>>>
>>>>> - Driver should enable the DRM_BUDDY_CLEARED flag if it
>>>>>    successfully clears the blocks in the free path. On the otherhand,
>>>>>    DRM buddy marks each block as cleared.
>>>>>
>>>>> - Track the available cleared pages size
>>>>>
>>>>> - If driver requests cleared memory we prefer cleared memory
>>>>>    but fallback to uncleared if we can't find the cleared blocks.
>>>>>    when driver requests uncleared memory we try to use uncleared but
>>>>>    fallback to cleared memory if necessary.
>>>>>
>>>>> - When a block gets freed we clear it and mark the freed block as 
>>>>> cleared,
>>>>>    when there are buddies which are cleared as well we can merge them.
>>>>>    Otherwise, we prefer to keep the blocks as separated.
>>>>>
>>>>> - Add a function to support defragmentation.
>>>>>
>>>>> v1:
>>>>>    - Depends on the flag check DRM_BUDDY_CLEARED, enable the block as
>>>>>      cleared. Else, reset the clear flag for each block in the 
>>>>> list(Christian)
>>>>>    - For merging the 2 cleared blocks compare as below,
>>>>>      drm_buddy_is_clear(block) != drm_buddy_is_clear(buddy)(Christian)
>>>>>    - Defragment the memory beginning from min_order
>>>>>      till the required memory space is available.
>>>>>
>>>>> v2: (Matthew)
>>>>>    - Add a wrapper drm_buddy_free_list_internal for the freeing of 
>>>>> blocks
>>>>>      operation within drm buddy.
>>>>>    - Write a macro block_incompatible() to allocate the required 
>>>>> blocks.
>>>>>    - Update the xe driver for the drm_buddy_free_list change in 
>>>>> arguments.
>>>>>    - add a warning if the two blocks are incompatible on
>>>>>      defragmentation
>>>>>    - call full defragmentation in the fini() function
>>>>>    - place a condition to test if min_order is equal to 0
>>>>>    - replace the list with safe_reverse() variant as we might
>>>>>      remove the block from the list.
>>>>>
>>>>> v3:
>>>>>    - fix Gitlab user reported lockup issue.
>>>>>    - Keep DRM_BUDDY_HEADER_CLEAR define sorted(Matthew)
>>>>>    - modify to pass the root order instead max_order in fini()
>>>>>      function(Matthew)
>>>>>    - change bool 1 to true(Matthew)
>>>>>    - add check if min_block_size is power of 2(Matthew)
>>>>>    - modify the min_block_size datatype to u64(Matthew)
>>>>>
>>>>> v4:
>>>>>    - rename the function drm_buddy_defrag with __force_merge.
>>>>>    - Include __force_merge directly in drm buddy file and remove
>>>>>      the defrag use in amdgpu driver.
>>>>>    - Remove list_empty() check(Matthew)
>>>>>    - Remove unnecessary space, headers and placement of new 
>>>>> variables(Matthew)
>>>>>    - Add a unit test case(Matthew)
>>>>>
>>>>> Signed-off-by: Arunpravin Paneer Selvam 
>>>>> <[e-mail]>
>>>>> Signed-off-by: Matthew Auld <[e-mail]>
>>>>> Suggested-by: Christian König <[e-mail]>
>>>>> Suggested-by: Matthew Auld <[e-mail]>
>>>>> ---
>>>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c  |   6 +-
>>>>>   drivers/gpu/drm/drm_buddy.c                   | 427 
>>>>> ++++++++++++++----
>>>>>   drivers/gpu/drm/i915/i915_ttm_buddy_manager.c |   6 +-
>>>>>   drivers/gpu/drm/tests/drm_buddy_test.c        |  18 +-
>>>>>   drivers/gpu/drm/xe/xe_ttm_vram_mgr.c          |   4 +-
>>>>>   include/drm/drm_buddy.h                       |  16 +-
>>>>>   6 files changed, 360 insertions(+), 117 deletions(-)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c 
>>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>>>>> index 8db880244324..c0c851409241 100644
>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>>>>> @@ -571,7 +571,7 @@ static int amdgpu_vram_mgr_new(struct 
>>>>> ttm_resource_manager *man,
>>>>>       return 0;
>>>>>     error_free_blocks:
>>>>> -    drm_buddy_free_list(mm, &vres->blocks);
>>>>> +    drm_buddy_free_list(mm, &vres->blocks, 0);
>>>>>       mutex_unlock(&mgr->lock);
>>>>>   error_fini:
>>>>>       ttm_resource_fini(man, &vres->base);
>>>>> @@ -604,7 +604,7 @@ static void amdgpu_vram_mgr_del(struct 
>>>>> ttm_resource_manager *man,
>>>>>         amdgpu_vram_mgr_do_reserve(man);
>>>>>   -    drm_buddy_free_list(mm, &vres->blocks);
>>>>> +    drm_buddy_free_list(mm, &vres->blocks, 0);
>>>>>       mutex_unlock(&mgr->lock);
>>>>>         atomic64_sub(vis_usage, &mgr->vis_usage);
>>>>> @@ -912,7 +912,7 @@ void amdgpu_vram_mgr_fini(struct amdgpu_device 
>>>>> *adev)
>>>>>           kfree(rsv);
>>>>>         list_for_each_entry_safe(rsv, temp, &mgr->reserved_pages, 
>>>>> blocks) {
>>>>> -        drm_buddy_free_list(&mgr->mm, &rsv->allocated);
>>>>> +        drm_buddy_free_list(&mgr->mm, &rsv->allocated, 0);
>>>>>           kfree(rsv);
>>>>>       }
>>>>>       if (!adev->gmc.is_app_apu)
>>>>> diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c
>>>>> index c4222b886db7..625a30a6b855 100644
>>>>> --- a/drivers/gpu/drm/drm_buddy.c
>>>>> +++ b/drivers/gpu/drm/drm_buddy.c
>>>>> @@ -38,8 +38,8 @@ static void drm_block_free(struct drm_buddy *mm,
>>>>>       kmem_cache_free(slab_blocks, block);
>>>>>   }
>>>>>   -static void list_insert_sorted(struct drm_buddy *mm,
>>>>> -                   struct drm_buddy_block *block)
>>>>> +static void list_insert(struct drm_buddy *mm,
>>>>> +            struct drm_buddy_block *block)
>>>>>   {
>>>>>       struct drm_buddy_block *node;
>>>>>       struct list_head *head;
>>>>> @@ -57,6 +57,16 @@ static void list_insert_sorted(struct drm_buddy 
>>>>> *mm,
>>>>>       __list_add(&block->link, node->link.prev, &node->link);
>>>>>   }
>>>>>   +static void clear_reset(struct drm_buddy_block *block)
>>>>> +{
>>>>> +    block->header &= ~DRM_BUDDY_HEADER_CLEAR;
>>>>> +}
>>>>> +
>>>>> +static void mark_cleared(struct drm_buddy_block *block)
>>>>> +{
>>>>> +    block->header |= DRM_BUDDY_HEADER_CLEAR;
>>>>> +}
>>>>> +
>>>>>   static void mark_allocated(struct drm_buddy_block *block)
>>>>>   {
>>>>>       block->header &= ~DRM_BUDDY_HEADER_STATE;
>>>>> @@ -71,7 +81,7 @@ static void mark_free(struct drm_buddy *mm,
>>>>>       block->header &= ~DRM_BUDDY_HEADER_STATE;
>>>>>       block->header |= DRM_BUDDY_FREE;
>>>>>   -    list_insert_sorted(mm, block);
>>>>> +    list_insert(mm, block);
>>>>>   }
>>>>>     static void mark_split(struct drm_buddy_block *block)
>>>>> @@ -82,6 +92,114 @@ static void mark_split(struct drm_buddy_block 
>>>>> *block)
>>>>>       list_del(&block->link);
>>>>>   }
>>>>>   +static struct drm_buddy_block *
>>>>> +__get_buddy(struct drm_buddy_block *block)
>>>>> +{
>>>>> +    struct drm_buddy_block *parent;
>>>>> +
>>>>> +    parent = block->parent;
>>>>> +    if (!parent)
>>>>> +        return NULL;
>>>>> +
>>>>> +    if (parent->left == block)
>>>>> +        return parent->right;
>>>>> +
>>>>> +    return parent->left;
>>>>> +}
>>>>> +
>>>>> +static unsigned int __drm_buddy_free(struct drm_buddy *mm,
>>>>> +                     struct drm_buddy_block *block,
>>>>> +                     bool force_merge)
>>>>> +{
>>>>> +    struct drm_buddy_block *parent;
>>>>> +    unsigned int order;
>>>>> +
>>>>> +    while ((parent = block->parent)) {
>>>>> +        struct drm_buddy_block *buddy;
>>>>> +
>>>>> +        buddy = __get_buddy(block);
>>>>> +
>>>>> +        if (!drm_buddy_block_is_free(buddy))
>>>>> +            break;
>>>>> +
>>>>> +        if (!force_merge) {
>>>>> +            /**
>>>>
>>>> Not really valid kernel-doc AFAIK. I think drop the extra *. Below 
>>>> also.
>>>>
>>>>> +             * Check the block and its buddy clear state and exit
>>>>> +             * the loop if they both have the dissimilar state.
>>>>> +             */
>>>>> +            if (drm_buddy_block_is_clear(block) !=
>>>>> +                drm_buddy_block_is_clear(buddy))
>>>>> +                break;
>>>>> +
>>>>> +            if (drm_buddy_block_is_clear(block))
>>>>> +                mark_cleared(parent);
>>>>> +        }
>>>>> +
>>>>> +        list_del(&buddy->link);
>>>>> +        if (force_merge && drm_buddy_block_is_clear(buddy))
>>>>> +            mm->clear_avail -= drm_buddy_block_size(mm, buddy);
>>>>> +
>>>>> +        drm_block_free(mm, block);
>>>>> +        drm_block_free(mm, buddy);
>>>>> +
>>>>> +        block = parent;
>>>>> +    }
>>>>> +
>>>>> +    order = drm_buddy_block_order(block);
>>>>> +    mark_free(mm, block);
>>>>> +
>>>>> +    return order;
>>>>> +}
>>>>> +
>>>>> +static int __force_merge(struct drm_buddy *mm,
>>>>> +             unsigned int min_order)
>>>>> +{
>>>>> +    unsigned int order;
>>>>> +    int i;
>>>>> +
>>>>> +    if (!min_order)
>>>>> +        return -ENOMEM;
>>>>> +
>>>>> +    if (min_order > mm->max_order)
>>>>> +        return -EINVAL;
>>>>> +
>>>>> +    for (i = min_order - 1; i >= 0; i--) {
>>>>> +        struct drm_buddy_block *block, *prev;
>>>>> +
>>>>> +        list_for_each_entry_safe_reverse(block, prev, 
>>>>> &mm->free_list[i], link) {
>>>>> +            struct drm_buddy_block *buddy;
>>>>> +
>>>>> +            if (!block->parent)
>>>>> +                continue;
>>>>> +
>>>>> +            buddy = __get_buddy(block);
>>>>> +            if (!drm_buddy_block_is_free(buddy))
>>>>> +                continue;
>>>>> +
>>>>> +            WARN_ON(drm_buddy_block_is_clear(block) ==
>>>>> +                drm_buddy_block_is_clear(buddy));
>>>>> +
>>>>> +            /**
>>>>> +             * If the prev block is same as buddy, don't access the
>>>>> +             * block in the next iteration as we would free the
>>>>> +             * buddy block as part of the free function.
>>>>> +             */
>>>>> +            if (prev == buddy)
>>>>> +                prev = list_prev_entry(prev, link);
>>>>> +
>>>>> +            list_del(&block->link);
>>>>> +            if (drm_buddy_block_is_clear(block))
>>>>> +                mm->clear_avail -= drm_buddy_block_size(mm, block);
>>>>> +
>>>>> +            order = __drm_buddy_free(mm, block, true);
>>>>> +            if (order >= min_order)
>>>>> +                return 0;
>>>>> +        }
>>>>> +    }
>>>>> +
>>>>> +    return -ENOMEM;
>>>>> +}
>>>>> +
>>>>>   /**
>>>>>    * drm_buddy_init - init memory manager
>>>>>    *
>>>>> @@ -137,7 +255,7 @@ int drm_buddy_init(struct drm_buddy *mm, u64 
>>>>> size, u64 chunk_size)
>>>>>       offset = 0;
>>>>>       i = 0;
>>>>>   -    /*
>>>>> +    /**
>>>>>        * Split into power-of-two blocks, in case we are given a 
>>>>> size that is
>>>>>        * not itself a power-of-two.
>>>>>        */
>>>>> @@ -186,11 +304,21 @@ EXPORT_SYMBOL(drm_buddy_init);
>>>>>    */
>>>>>   void drm_buddy_fini(struct drm_buddy *mm)
>>>>>   {
>>>>> +    u64 root_size, size;
>>>>> +    unsigned int order;
>>>>>       int i;
>>>>>   +    size = mm->size;
>>>>> +
>>>>>       for (i = 0; i < mm->n_roots; ++i) {
>>>>> +        order = ilog2(size) - ilog2(mm->chunk_size);
>>>>> +        __force_merge(mm, order);
>>>>> +
>>>>> WARN_ON(!drm_buddy_block_is_free(mm->roots[i]));
>>>>>           drm_block_free(mm, mm->roots[i]);
>>>>> +
>>>>> +        root_size = mm->chunk_size << order;
>>>>> +        size -= root_size;
>>>>>       }
>>>>>         WARN_ON(mm->avail != mm->size);
>>>>> @@ -223,26 +351,17 @@ static int split_block(struct drm_buddy *mm,
>>>>>       mark_free(mm, block->left);
>>>>>       mark_free(mm, block->right);
>>>>>   +    if (drm_buddy_block_is_clear(block)) {
>>>>> +        mark_cleared(block->left);
>>>>> +        mark_cleared(block->right);
>>>>> +        clear_reset(block);
>>>>> +    }
>>>>> +
>>>>>       mark_split(block);
>>>>>         return 0;
>>>>>   }
>>>>>   -static struct drm_buddy_block *
>>>>> -__get_buddy(struct drm_buddy_block *block)
>>>>> -{
>>>>> -    struct drm_buddy_block *parent;
>>>>> -
>>>>> -    parent = block->parent;
>>>>> -    if (!parent)
>>>>> -        return NULL;
>>>>> -
>>>>> -    if (parent->left == block)
>>>>> -        return parent->right;
>>>>> -
>>>>> -    return parent->left;
>>>>> -}
>>>>> -
>>>>>   /**
>>>>>    * drm_get_buddy - get buddy address
>>>>>    *
>>>>> @@ -260,30 +379,6 @@ drm_get_buddy(struct drm_buddy_block *block)
>>>>>   }
>>>>>   EXPORT_SYMBOL(drm_get_buddy);
>>>>>   -static void __drm_buddy_free(struct drm_buddy *mm,
>>>>> -                 struct drm_buddy_block *block)
>>>>> -{
>>>>> -    struct drm_buddy_block *parent;
>>>>> -
>>>>> -    while ((parent = block->parent)) {
>>>>> -        struct drm_buddy_block *buddy;
>>>>> -
>>>>> -        buddy = __get_buddy(block);
>>>>> -
>>>>> -        if (!drm_buddy_block_is_free(buddy))
>>>>> -            break;
>>>>> -
>>>>> -        list_del(&buddy->link);
>>>>> -
>>>>> -        drm_block_free(mm, block);
>>>>> -        drm_block_free(mm, buddy);
>>>>> -
>>>>> -        block = parent;
>>>>> -    }
>>>>> -
>>>>> -    mark_free(mm, block);
>>>>> -}
>>>>> -
>>>>>   /**
>>>>>    * drm_buddy_free_block - free a block
>>>>>    *
>>>>> @@ -295,26 +390,59 @@ void drm_buddy_free_block(struct drm_buddy *mm,
>>>>>   {
>>>>>       BUG_ON(!drm_buddy_block_is_allocated(block));
>>>>>       mm->avail += drm_buddy_block_size(mm, block);
>>>>> -    __drm_buddy_free(mm, block);
>>>>> +    if (drm_buddy_block_is_clear(block))
>>>>> +        mm->clear_avail += drm_buddy_block_size(mm, block);
>>>>> +
>>>>> +    __drm_buddy_free(mm, block, false);
>>>>>   }
>>>>>   EXPORT_SYMBOL(drm_buddy_free_block);
>>>>>   -/**
>>>>> - * drm_buddy_free_list - free blocks
>>>>> - *
>>>>> - * @mm: DRM buddy manager
>>>>> - * @objects: input list head to free blocks
>>>>> - */
>>>>> -void drm_buddy_free_list(struct drm_buddy *mm, struct list_head 
>>>>> *objects)
>>>>> +static void __drm_buddy_free_list(struct drm_buddy *mm,
>>>>> +                  struct list_head *objects,
>>>>> +                  bool mark_clear,
>>>>> +                  bool mark_dirty)
>>>>>   {
>>>>>       struct drm_buddy_block *block, *on;
>>>>>   +    WARN_ON(mark_dirty && mark_clear);
>>>>> +
>>>>>       list_for_each_entry_safe(block, on, objects, link) {
>>>>> +        if (mark_clear)
>>>>> +            mark_cleared(block);
>>>>> +        else if (mark_dirty)
>>>>> +            clear_reset(block);
>>>>>           drm_buddy_free_block(mm, block);
>>>>>           cond_resched();
>>>>>       }
>>>>>       INIT_LIST_HEAD(objects);
>>>>>   }
>>>>> +
>>>>> +static void drm_buddy_free_list_internal(struct drm_buddy *mm,
>>>>> +                     struct list_head *objects)
>>>>> +{
>>>>> +    /**
>>>>> +     * Don't touch the clear/dirty bit, since allocation is still 
>>>>> internal
>>>>> +     * at this point. For example we might have just failed part 
>>>>> of the
>>>>> +     * allocation.
>>>>> +     */
>>>>> +    __drm_buddy_free_list(mm, objects, false, false);
>>>>> +}
>>>>> +
>>>>> +/**
>>>>> + * drm_buddy_free_list - free blocks
>>>>> + *
>>>>> + * @mm: DRM buddy manager
>>>>> + * @objects: input list head to free blocks
>>>>> + * @flags: optional flags like DRM_BUDDY_CLEARED
>>>>> + */
>>>>> +void drm_buddy_free_list(struct drm_buddy *mm,
>>>>> +             struct list_head *objects,
>>>>> +             unsigned int flags)
>>>>> +{
>>>>> +    bool mark_clear = flags & DRM_BUDDY_CLEARED;
>>>>> +
>>>>> +    __drm_buddy_free_list(mm, objects, mark_clear, !mark_clear);
>>>>> +}
>>>>>   EXPORT_SYMBOL(drm_buddy_free_list);
>>>>>     static inline bool overlaps(u64 s1, u64 e1, u64 s2, u64 e2)
>>>>> @@ -327,10 +455,19 @@ static inline bool contains(u64 s1, u64 e1, 
>>>>> u64 s2, u64 e2)
>>>>>       return s1 <= s2 && e1 >= e2;
>>>>>   }
>>>>>   +static bool block_incompatible(struct drm_buddy_block *block, 
>>>>> unsigned int flags)
>>>>> +{
>>>>> +    bool needs_clear = flags & DRM_BUDDY_CLEAR_ALLOCATION;
>>>>> +
>>>>> +    return needs_clear != drm_buddy_block_is_clear(block);
>>>>> +}
>>>>> +
>>>>>   static struct drm_buddy_block *
>>>>> -alloc_range_bias(struct drm_buddy *mm,
>>>>> -         u64 start, u64 end,
>>>>> -         unsigned int order)
>>>>> +__alloc_range_bias(struct drm_buddy *mm,
>>>>> +           u64 start, u64 end,
>>>>> +           unsigned int order,
>>>>> +           unsigned long flags,
>>>>> +           bool fallback)
>>>>>   {
>>>>>       struct drm_buddy_block *block;
>>>>>       struct drm_buddy_block *buddy;
>>>>> @@ -369,7 +506,10 @@ alloc_range_bias(struct drm_buddy *mm,
>>>>>             if (contains(start, end, block_start, block_end) &&
>>>>>               order == drm_buddy_block_order(block)) {
>>>>> -            /*
>>>>> +            if (!fallback && block_incompatible(block, flags))
>>>>> +                continue;
>>>>> +
>>>>> +            /**
>>>>>                * Find the free block within the range.
>>>>>                */
>>>>>               if (drm_buddy_block_is_free(block))
>>>>> @@ -391,7 +531,7 @@ alloc_range_bias(struct drm_buddy *mm,
>>>>>       return ERR_PTR(-ENOSPC);
>>>>>     err_undo:
>>>>> -    /*
>>>>> +    /**
>>>>>        * We really don't want to leave around a bunch of split 
>>>>> blocks, since
>>>>>        * bigger is better, so make sure we merge everything back 
>>>>> before we
>>>>>        * free the allocated blocks.
>>>>> @@ -400,30 +540,57 @@ alloc_range_bias(struct drm_buddy *mm,
>>>>>       if (buddy &&
>>>>>           (drm_buddy_block_is_free(block) &&
>>>>>            drm_buddy_block_is_free(buddy)))
>>>>> -        __drm_buddy_free(mm, block);
>>>>> +        __drm_buddy_free(mm, block, false);
>>>>>       return ERR_PTR(err);
>>>>>   }
>>>>>     static struct drm_buddy_block *
>>>>> -get_maxblock(struct drm_buddy *mm, unsigned int order)
>>>>> +__drm_buddy_alloc_range_bias(struct drm_buddy *mm,
>>>>> +                 u64 start, u64 end,
>>>>> +                 unsigned int order,
>>>>> +                 unsigned long flags)
>>>>> +{
>>>>> +    struct drm_buddy_block *block;
>>>>> +    bool fallback = false;
>>>>> +
>>>>> +    block = __alloc_range_bias(mm, start, end, order,
>>>>> +                   flags, fallback);
>>>>> +    if (IS_ERR(block) && mm->clear_avail)
>>>>> +        return __alloc_range_bias(mm, start, end, order,
>>>>> +                      flags, !fallback);
>>>>> +
>>>>> +    return block;
>>>>> +}
>>>>> +
>>>>> +static struct drm_buddy_block *
>>>>> +get_maxblock(struct drm_buddy *mm, unsigned int order,
>>>>> +         unsigned long flags)
>>>>>   {
>>>>> -    struct drm_buddy_block *max_block = NULL, *node;
>>>>> +    struct drm_buddy_block *max_block = NULL, *block = NULL;
>>>>>       unsigned int i;
>>>>>         for (i = order; i <= mm->max_order; ++i) {
>>>>> -        if (!list_empty(&mm->free_list[i])) {
>>>>> -            node = list_last_entry(&mm->free_list[i],
>>>>> -                           struct drm_buddy_block,
>>>>> -                           link);
>>>>> -            if (!max_block) {
>>>>> -                max_block = node;
>>>>> +        struct drm_buddy_block *tmp_block;
>>>>> +
>>>>> +        list_for_each_entry_reverse(tmp_block, &mm->free_list[i], 
>>>>> link) {
>>>>> +            if (block_incompatible(tmp_block, flags))
>>>>>                   continue;
>>>>> -            }
>>>>>   -            if (drm_buddy_block_offset(node) >
>>>>> -                drm_buddy_block_offset(max_block)) {
>>>>> -                max_block = node;
>>>>> -            }
>>>>> +            block = tmp_block;
>>>>> +            break;
>>>>> +        }
>>>>> +
>>>>> +        if (!block)
>>>>> +            continue;
>>>>> +
>>>>> +        if (!max_block) {
>>>>> +            max_block = block;
>>>>> +            continue;
>>>>> +        }
>>>>> +
>>>>> +        if (drm_buddy_block_offset(block) >
>>>>> +            drm_buddy_block_offset(max_block)) {
>>>>> +            max_block = block;
>>>>>           }
>>>>>       }
>>>>>   @@ -440,11 +607,29 @@ alloc_from_freelist(struct drm_buddy *mm,
>>>>>       int err;
>>>>>         if (flags & DRM_BUDDY_TOPDOWN_ALLOCATION) {
>>>>> -        block = get_maxblock(mm, order);
>>>>> +        block = get_maxblock(mm, order, flags);
>>>>>           if (block)
>>>>>               /* Store the obtained block order */
>>>>>               tmp = drm_buddy_block_order(block);
>>>>>       } else {
>>>>> +        for (tmp = order; tmp <= mm->max_order; ++tmp) {
>>>>> +            struct drm_buddy_block *tmp_block;
>>>>> +
>>>>> +            list_for_each_entry_reverse(tmp_block, 
>>>>> &mm->free_list[tmp], link) {
>>>>> +                if (block_incompatible(tmp_block, flags))
>>>>> +                    continue;
>>>>> +
>>>>> +                block = tmp_block;
>>>>> +                break;
>>>>> +            }
>>>>> +
>>>>> +            if (block)
>>>>> +                break;
>>>>> +        }
>>>>> +    }
>>>>> +
>>>>> +    if (!block) {
>>>>> +        /* Fallback method */
>>>>>           for (tmp = order; tmp <= mm->max_order; ++tmp) {
>>>>>               if (!list_empty(&mm->free_list[tmp])) {
>>>>>                   block = list_last_entry(&mm->free_list[tmp],
>>>>> @@ -454,10 +639,10 @@ alloc_from_freelist(struct drm_buddy *mm,
>>>>>                       break;
>>>>>               }
>>>>>           }
>>>>> -    }
>>>>>   -    if (!block)
>>>>> -        return ERR_PTR(-ENOSPC);
>>>>> +        if (!block)
>>>>> +            return ERR_PTR(-ENOSPC);
>>>>> +    }
>>>>>         BUG_ON(!drm_buddy_block_is_free(block));
>>>>>   @@ -473,7 +658,7 @@ alloc_from_freelist(struct drm_buddy *mm,
>>>>>     err_undo:
>>>>>       if (tmp != order)
>>>>> -        __drm_buddy_free(mm, block);
>>>>> +        __drm_buddy_free(mm, block, false);
>>>>>       return ERR_PTR(err);
>>>>>   }
>>>>>   @@ -524,6 +709,8 @@ static int __alloc_range(struct drm_buddy *mm,
>>>>>               mark_allocated(block);
>>>>>               total_allocated += drm_buddy_block_size(mm, block);
>>>>>               mm->avail -= drm_buddy_block_size(mm, block);
>>>>> +            if (drm_buddy_block_is_clear(block))
>>>>> +                mm->clear_avail -= drm_buddy_block_size(mm, block);
>>>>>               list_add_tail(&block->link, &allocated);
>>>>>               continue;
>>>>>           }
>>>>> @@ -548,7 +735,7 @@ static int __alloc_range(struct drm_buddy *mm,
>>>>>       return 0;
>>>>>     err_undo:
>>>>> -    /*
>>>>> +    /**
>>>>>        * We really don't want to leave around a bunch of split 
>>>>> blocks, since
>>>>>        * bigger is better, so make sure we merge everything back 
>>>>> before we
>>>>>        * free the allocated blocks.
>>>>> @@ -557,14 +744,14 @@ static int __alloc_range(struct drm_buddy *mm,
>>>>>       if (buddy &&
>>>>>           (drm_buddy_block_is_free(block) &&
>>>>>            drm_buddy_block_is_free(buddy)))
>>>>> -        __drm_buddy_free(mm, block);
>>>>> +        __drm_buddy_free(mm, block, false);
>>>>>     err_free:
>>>>>       if (err == -ENOSPC && total_allocated_on_err) {
>>>>>           list_splice_tail(&allocated, blocks);
>>>>>           *total_allocated_on_err = total_allocated;
>>>>>       } else {
>>>>> -        drm_buddy_free_list(mm, &allocated);
>>>>> +        drm_buddy_free_list_internal(mm, &allocated);
>>>>>       }
>>>>>         return err;
>>>>> @@ -630,11 +817,11 @@ static int __alloc_contig_try_harder(struct 
>>>>> drm_buddy *mm,
>>>>>               list_splice(&blocks_lhs, blocks);
>>>>>               return 0;
>>>>>           } else if (err != -ENOSPC) {
>>>>> -            drm_buddy_free_list(mm, blocks);
>>>>> +            drm_buddy_free_list_internal(mm, blocks);
>>>>>               return err;
>>>>>           }
>>>>>           /* Free blocks for the next iteration */
>>>>> -        drm_buddy_free_list(mm, blocks);
>>>>> +        drm_buddy_free_list_internal(mm, blocks);
>>>>>       }
>>>>>         return -ENOSPC;
>>>>> @@ -690,6 +877,8 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>>>>>       list_del(&block->link);
>>>>>       mark_free(mm, block);
>>>>>       mm->avail += drm_buddy_block_size(mm, block);
>>>>> +    if (drm_buddy_block_is_clear(block))
>>>>> +        mm->clear_avail += drm_buddy_block_size(mm, block);
>>>>>         /* Prevent recursively freeing this node */
>>>>>       parent = block->parent;
>>>>> @@ -701,6 +890,8 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>>>>>       if (err) {
>>>>>           mark_allocated(block);
>>>>>           mm->avail -= drm_buddy_block_size(mm, block);
>>>>> +        if (drm_buddy_block_is_clear(block))
>>>>> +            mm->clear_avail -= drm_buddy_block_size(mm, block);
>>>>>           list_add(&block->link, blocks);
>>>>>       }
>>>>>   @@ -709,13 +900,28 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>>>>>   }
>>>>>   EXPORT_SYMBOL(drm_buddy_block_trim);
>>>>>   +static struct drm_buddy_block *
>>>>> +__drm_buddy_alloc_blocks(struct drm_buddy *mm,
>>>>> +             u64 start, u64 end,
>>>>> +             unsigned int order,
>>>>> +             unsigned long flags)
>>>>> +{
>>>>> +    if (flags & DRM_BUDDY_RANGE_ALLOCATION)
>>>>> +        /* Allocate traversing within the range */
>>>>> +        return  __drm_buddy_alloc_range_bias(mm, start, end,
>>>>> +                             order, flags);
>>>>> +    else
>>>>> +        /* Allocate from freelist */
>>>>> +        return alloc_from_freelist(mm, order, flags);
>>>>> +}
>>>>> +
>>>>>   /**
>>>>>    * drm_buddy_alloc_blocks - allocate power-of-two blocks
>>>>>    *
>>>>>    * @mm: DRM buddy manager to allocate from
>>>>>    * @start: start of the allowed range for this block
>>>>>    * @end: end of the allowed range for this block
>>>>> - * @size: size of the allocation
>>>>> + * @size: size of the allocation in bytes
>>>>>    * @min_block_size: alignment of the allocation
>>>>>    * @blocks: output list head to add allocated blocks
>>>>>    * @flags: DRM_BUDDY_*_ALLOCATION flags
>>>>> @@ -761,8 +967,18 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>>>>>           return -EINVAL;
>>>>>         /* Actual range allocation */
>>>>> -    if (start + size == end)
>>>>> -        return __drm_buddy_alloc_range(mm, start, size, NULL, 
>>>>> blocks);
>>>>> +    if (start + size == end) {
>>>>> +        err =  __drm_buddy_alloc_range(mm, start, size, NULL, 
>>>>> blocks);
>>>>> +        if (err) {
>>>>> +            order = ilog2(size) - ilog2(mm->chunk_size);
>>>>> +            if (mm->clear_avail && !__force_merge(mm, order))
>>>>> +                return __drm_buddy_alloc_range(mm, start, size, 
>>>>> NULL, blocks);
>>>>
>>>> That seems strange at a glance. With an actual range allocation like 
>>>> with intitial fb or whatever it should just find all overlapping 
>>>> pages, splitting down where needed on the edges. Not sure why 
>>>> force_merge would factor in here?
>>> In case of not merged (fragmentation due to dirty and clear pages 
>>> split), if the memory request goes into that range, we might see the 
>>> split blocks as not free and end up returning -ENOSPC.
>>> I found this problem when I tried to allocate the max_order where the 
>>> start + size == end and it ends up entering into this code block and 
>>> it returns -ENOSPC as there is no force_merge call
>>> and the requested range max order block seen as not free. And we have 
>>> an another issue though if we use force_merge to defragment a 
>>> specific ordered block, there is a less probability that
>>> we merge back the required blocks in the specific range. For now, we 
>>> can go ahead with no force merge support for actual range allocation 
>>> if we are sure that we use this only for initial fb etc.
>>
>> Ah right, now I see. But AFAICT trouble is if we say allocate 8K range 
>> at some specific offset, like above, which fails due to clear/dirty 
>> split then calling force_merge(order(8K)) is not always going to help. 
>> It will just force merge enough for 8K, but that might not be the 8K 
>> at the offset we were looking for, so it still fails. I think perhaps 
>> update the dfs in alloc_range to not bail when contains && split. Or I 
>> think other option is to force merge the entire address space on err. 
>> Other ideas?
> For actual range allocation, if the min_block_size == mm->chunk_size, I 
> think we can proceed with your first idea (i.e) update the dfs in 
> alloc_range to not bail when contains && split.
> For bias range allocation, we need to add range support to the 
> force_merge, for instance we can just continue in the force_merge for 
> loop if the contains(start, end, block_start, block_end) returns false.
> Thoughts?

Yeah, I think something like that should work.

> 
> Thanks,
> Arun.
>>
>>>
>>> If there are no major concerns, can we push these patches?
>>>
>>> Regards,
>>> Arun.
>>>>> +
>>>>> +            return err;
>>>>> +        }
>>>>> +
>>>>> +        return err;
>>>>> +    }
>>>>>         original_size = size;
>>>>>       original_min_size = min_block_size;
>>>>> @@ -786,23 +1002,34 @@ int drm_buddy_alloc_blocks(struct drm_buddy 
>>>>> *mm,
>>>>>           BUG_ON(order < min_order);
>>>>>             do {
>>>>> -            if (flags & DRM_BUDDY_RANGE_ALLOCATION)
>>>>> -                /* Allocate traversing within the range */
>>>>> -                block = alloc_range_bias(mm, start, end, order);
>>>>> -            else
>>>>> -                /* Allocate from freelist */
>>>>> -                block = alloc_from_freelist(mm, order, flags);
>>>>> -
>>>>> +            block = __drm_buddy_alloc_blocks(mm, start,
>>>>> +                             end,
>>>>> +                             order,
>>>>> +                             flags);
>>>>>               if (!IS_ERR(block))
>>>>>                   break;
>>>>>                 if (order-- == min_order) {
>>>>> +                /**
>>>>> +                 * Try allocation through force merge method
>>>>> +                 */
>>>>> +                if (mm->clear_avail && !__force_merge(mm, 
>>>>> min_order)) {
>>>>> +                    block = __drm_buddy_alloc_blocks(mm, start,
>>>>> +                                     end,
>>>>> +                                     min_order,
>>>>> +                                     flags);
>>>>> +                    if (!IS_ERR(block)) {
>>>>> +                        order = min_order;
>>>>> +                        break;
>>>>> +                    }
>>>>> +                }
>>>>> +
>>>>> +    ��           /**
>>>>> +                 * Try contiguous block allocation through
>>>>> +                 * try harder method.
>>>>> +                 */
>>>>>                   if (flags & DRM_BUDDY_CONTIGUOUS_ALLOCATION &&
>>>>>                       !(flags & DRM_BUDDY_RANGE_ALLOCATION))
>>>>> -                    /*
>>>>> -                     * Try contiguous block allocation through
>>>>> -                     * try harder method
>>>>> -                     */
>>>>>                       return __alloc_contig_try_harder(mm,
>>>>>                                        original_size,
>>>>>                                        original_min_size,
>>>>> @@ -814,6 +1041,8 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>>>>>             mark_allocated(block);
>>>>>           mm->avail -= drm_buddy_block_size(mm, block);
>>>>> +        if (drm_buddy_block_is_clear(block))
>>>>> +            mm->clear_avail -= drm_buddy_block_size(mm, block);
>>>>>           kmemleak_update_trace(block);
>>>>>           list_add_tail(&block->link, &allocated);
>>>>>   @@ -823,7 +1052,9 @@ int drm_buddy_alloc_blocks(struct drm_buddy 
>>>>> *mm,
>>>>>               break;
>>>>>       } while (1);
>>>>>   -    /* Trim the allocated block to the required size */
>>>>> +    /**
>>>>> +     * Trim the allocated block to the required size
>>>>> +     */
>>>>>       if (original_size != size) {
>>>>>           struct list_head *trim_list;
>>>>>           LIST_HEAD(temp);
>>>>> @@ -852,7 +1083,7 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>>>>>       return 0;
>>>>>     err_free:
>>>>> -    drm_buddy_free_list(mm, &allocated);
>>>>> +    drm_buddy_free_list_internal(mm, &allocated);
>>>>>       return err;
>>>>>   }
>>>>>   EXPORT_SYMBOL(drm_buddy_alloc_blocks);
>>>>> @@ -885,8 +1116,8 @@ void drm_buddy_print(struct drm_buddy *mm, 
>>>>> struct drm_printer *p)
>>>>>   {
>>>>>       int order;
>>>>>   -    drm_printf(p, "chunk_size: %lluKiB, total: %lluMiB, free: 
>>>>> %lluMiB\n",
>>>>> -           mm->chunk_size >> 10, mm->size >> 20, mm->avail >> 20);
>>>>> +    drm_printf(p, "chunk_size: %lluKiB, total: %lluMiB, free: 
>>>>> %lluMiB, clear_free: %lluMiB\n",
>>>>> +           mm->chunk_size >> 10, mm->size >> 20, mm->avail >> 20, 
>>>>> mm->clear_avail >> 20);
>>>>>         for (order = mm->max_order; order >= 0; order--) {
>>>>>           struct drm_buddy_block *block;
>>>>> diff --git a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c 
>>>>> b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
>>>>> index 0d735d5c2b35..942345548bc3 100644
>>>>> --- a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
>>>>> +++ b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
>>>>> @@ -126,7 +126,7 @@ static int i915_ttm_buddy_man_alloc(struct 
>>>>> ttm_resource_manager *man,
>>>>>       return 0;
>>>>>     err_free_blocks:
>>>>> -    drm_buddy_free_list(mm, &bman_res->blocks);
>>>>> +    drm_buddy_free_list(mm, &bman_res->blocks, 0);
>>>>>       mutex_unlock(&bman->lock);
>>>>>   err_free_res:
>>>>>       ttm_resource_fini(man, &bman_res->base);
>>>>> @@ -141,7 +141,7 @@ static void i915_ttm_buddy_man_free(struct 
>>>>> ttm_resource_manager *man,
>>>>>       struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
>>>>>         mutex_lock(&bman->lock);
>>>>> -    drm_buddy_free_list(&bman->mm, &bman_res->blocks);
>>>>> +    drm_buddy_free_list(&bman->mm, &bman_res->blocks, 0);
>>>>>       bman->visible_avail += bman_res->used_visible_size;
>>>>>       mutex_unlock(&bman->lock);
>>>>>   @@ -345,7 +345,7 @@ int i915_ttm_buddy_man_fini(struct ttm_device 
>>>>> *bdev, unsigned int type)
>>>>>       ttm_set_driver_manager(bdev, type, NULL);
>>>>>         mutex_lock(&bman->lock);
>>>>> -    drm_buddy_free_list(mm, &bman->reserved);
>>>>> +    drm_buddy_free_list(mm, &bman->reserved, 0);
>>>>>       drm_buddy_fini(mm);
>>>>>       bman->visible_avail += bman->visible_reserved;
>>>>>       WARN_ON_ONCE(bman->visible_avail != bman->visible_size);
>>>>> diff --git a/drivers/gpu/drm/tests/drm_buddy_test.c 
>>>>> b/drivers/gpu/drm/tests/drm_buddy_test.c
>>>>> index 2f32fb2f12e7..454ad9952f56 100644
>>>>> --- a/drivers/gpu/drm/tests/drm_buddy_test.c
>>>>> +++ b/drivers/gpu/drm/tests/drm_buddy_test.c
>>>>> @@ -64,7 +64,7 @@ static void 
>>>>> drm_test_buddy_alloc_contiguous(struct kunit *test)
>>>>> DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>>>>>                      "buddy_alloc didn't error size=%u\n", 3 * ps);
>>>>>   -    drm_buddy_free_list(&mm, &middle);
>>>>> +    drm_buddy_free_list(&mm, &middle, 0);
>>>>>       KUNIT_ASSERT_TRUE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, 
>>>>> mm_size,
>>>>>                                  3 * ps, ps, &allocated,
>>>>> DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>>>>> @@ -74,7 +74,7 @@ static void 
>>>>> drm_test_buddy_alloc_contiguous(struct kunit *test)
>>>>> DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>>>>>                      "buddy_alloc didn't error size=%u\n", 2 * ps);
>>>>>   -    drm_buddy_free_list(&mm, &right);
>>>>> +    drm_buddy_free_list(&mm, &right, 0);
>>>>>       KUNIT_ASSERT_TRUE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, 
>>>>> mm_size,
>>>>>                                  3 * ps, ps, &allocated,
>>>>> DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>>>>> @@ -89,7 +89,7 @@ static void 
>>>>> drm_test_buddy_alloc_contiguous(struct kunit *test)
>>>>> DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>>>>>                      "buddy_alloc hit an error size=%u\n", 2 * ps);
>>>>>   -    drm_buddy_free_list(&mm, &left);
>>>>> +    drm_buddy_free_list(&mm, &left, 0);
>>>>>       KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, 
>>>>> mm_size,
>>>>>                                   3 * ps, ps, &allocated,
>>>>> DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>>>>> @@ -101,7 +101,7 @@ static void 
>>>>> drm_test_buddy_alloc_contiguous(struct kunit *test)
>>>>>         KUNIT_ASSERT_EQ(test, total, ps * 2 + ps * 3);
>>>>>   -    drm_buddy_free_list(&mm, &allocated);
>>>>> +    drm_buddy_free_list(&mm, &allocated, 0);
>>>>>       drm_buddy_fini(&mm);
>>>>>   }
>>>>>   @@ -170,7 +170,7 @@ static void 
>>>>> drm_test_buddy_alloc_pathological(struct kunit *test)
>>>>>                                 top, max_order);
>>>>>       }
>>>>>   -    drm_buddy_free_list(&mm, &holes);
>>>>> +    drm_buddy_free_list(&mm, &holes, 0);
>>>>>         /* Nothing larger than blocks of chunk_size now available */
>>>>>       for (order = 1; order <= max_order; order++) {
>>>>> @@ -182,7 +182,7 @@ static void 
>>>>> drm_test_buddy_alloc_pathological(struct kunit *test)
>>>>>       }
>>>>>         list_splice_tail(&holes, &blocks);
>>>>> -    drm_buddy_free_list(&mm, &blocks);
>>>>> +    drm_buddy_free_list(&mm, &blocks, 0);
>>>>>       drm_buddy_fini(&mm);
>>>>>   }
>>>>>   @@ -277,7 +277,7 @@ static void 
>>>>> drm_test_buddy_alloc_pessimistic(struct kunit *test)
>>>>>         list_del(&block->link);
>>>>>       drm_buddy_free_block(&mm, block);
>>>>> -    drm_buddy_free_list(&mm, &blocks);
>>>>> +    drm_buddy_free_list(&mm, &blocks, 0);
>>>>>       drm_buddy_fini(&mm);
>>>>>   }
>>>>>   @@ -323,7 +323,7 @@ static void 
>>>>> drm_test_buddy_alloc_optimistic(struct kunit *test)
>>>>>                                  size, size, &tmp, flags),
>>>>>                             "buddy_alloc unexpectedly succeeded, it 
>>>>> should be full!");
>>>>>   -    drm_buddy_free_list(&mm, &blocks);
>>>>> +    drm_buddy_free_list(&mm, &blocks, 0);
>>>>>       drm_buddy_fini(&mm);
>>>>>   }
>>>>>   @@ -358,7 +358,7 @@ static void drm_test_buddy_alloc_limit(struct 
>>>>> kunit *test)
>>>>>                           drm_buddy_block_size(&mm, block),
>>>>>                           BIT_ULL(mm.max_order) * PAGE_SIZE);
>>>>>   -    drm_buddy_free_list(&mm, &allocated);
>>>>> +    drm_buddy_free_list(&mm, &allocated, 0);
>>>>>       drm_buddy_fini(&mm);
>>>>>   }
>>>>>   diff --git a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c 
>>>>> b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
>>>>> index 115ec745e502..1ad678b62c4a 100644
>>>>> --- a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
>>>>> +++ b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
>>>>> @@ -196,7 +196,7 @@ static int xe_ttm_vram_mgr_new(struct 
>>>>> ttm_resource_manager *man,
>>>>>       return 0;
>>>>>     error_free_blocks:
>>>>> -    drm_buddy_free_list(mm, &vres->blocks);
>>>>> +    drm_buddy_free_list(mm, &vres->blocks, 0);
>>>>>       mutex_unlock(&mgr->lock);
>>>>>   error_fini:
>>>>>       ttm_resource_fini(man, &vres->base);
>>>>> @@ -214,7 +214,7 @@ static void xe_ttm_vram_mgr_del(struct 
>>>>> ttm_resource_manager *man,
>>>>>       struct drm_buddy *mm = &mgr->mm;
>>>>>         mutex_lock(&mgr->lock);
>>>>> -    drm_buddy_free_list(mm, &vres->blocks);
>>>>> +    drm_buddy_free_list(mm, &vres->blocks, 0);
>>>>>       mgr->visible_avail += vres->used_visible_size;
>>>>>       mutex_unlock(&mgr->lock);
>>>>>   diff --git a/include/drm/drm_buddy.h b/include/drm/drm_buddy.h
>>>>> index a5b39fc01003..82570f77e817 100644
>>>>> --- a/include/drm/drm_buddy.h
>>>>> +++ b/include/drm/drm_buddy.h
>>>>> @@ -25,6 +25,8 @@
>>>>>   #define DRM_BUDDY_RANGE_ALLOCATION        BIT(0)
>>>>>   #define DRM_BUDDY_TOPDOWN_ALLOCATION        BIT(1)
>>>>>   #define DRM_BUDDY_CONTIGUOUS_ALLOCATION        BIT(2)
>>>>> +#define DRM_BUDDY_CLEAR_ALLOCATION        BIT(3)
>>>>> +#define DRM_BUDDY_CLEARED            BIT(4)
>>>>>     struct drm_buddy_block {
>>>>>   #define DRM_BUDDY_HEADER_OFFSET GENMASK_ULL(63, 12)
>>>>> @@ -32,8 +34,9 @@ struct drm_buddy_block {
>>>>>   #define   DRM_BUDDY_ALLOCATED       (1 << 10)
>>>>>   #define   DRM_BUDDY_FREE       (2 << 10)
>>>>>   #define   DRM_BUDDY_SPLIT       (3 << 10)
>>>>> +#define DRM_BUDDY_HEADER_CLEAR  GENMASK_ULL(9, 9)
>>>>>   /* Free to be used, if needed in the future */
>>>>> -#define DRM_BUDDY_HEADER_UNUSED GENMASK_ULL(9, 6)
>>>>> +#define DRM_BUDDY_HEADER_UNUSED GENMASK_ULL(8, 6)
>>>>>   #define DRM_BUDDY_HEADER_ORDER  GENMASK_ULL(5, 0)
>>>>>       u64 header;
>>>>>   @@ -86,6 +89,7 @@ struct drm_buddy {
>>>>>       u64 chunk_size;
>>>>>       u64 size;
>>>>>       u64 avail;
>>>>> +    u64 clear_avail;
>>>>>   };
>>>>>     static inline u64
>>>>> @@ -112,6 +116,12 @@ drm_buddy_block_is_allocated(struct 
>>>>> drm_buddy_block *block)
>>>>>       return drm_buddy_block_state(block) == DRM_BUDDY_ALLOCATED;
>>>>>   }
>>>>>   +static inline bool
>>>>> +drm_buddy_block_is_clear(struct drm_buddy_block *block)
>>>>> +{
>>>>> +    return block->header & DRM_BUDDY_HEADER_CLEAR;
>>>>> +}
>>>>> +
>>>>>   static inline bool
>>>>>   drm_buddy_block_is_free(struct drm_buddy_block *block)
>>>>>   {
>>>>> @@ -150,7 +160,9 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>>>>>     void drm_buddy_free_block(struct drm_buddy *mm, struct 
>>>>> drm_buddy_block *block);
>>>>>   -void drm_buddy_free_list(struct drm_buddy *mm, struct list_head 
>>>>> *objects);
>>>>> +void drm_buddy_free_list(struct drm_buddy *mm,
>>>>> +             struct list_head *objects,
>>>>> +             unsigned int flags);
>>>>>     void drm_buddy_print(struct drm_buddy *mm, struct drm_printer *p);
>>>>>   void drm_buddy_block_print(struct drm_buddy *mm,
>>>
>

Patch

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
index 8db880244324..c0c851409241 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
@@ -571,7 +571,7 @@  static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
 	return 0;
 
 error_free_blocks:
-	drm_buddy_free_list(mm, &vres->blocks);
+	drm_buddy_free_list(mm, &vres->blocks, 0);
 	mutex_unlock(&mgr->lock);
 error_fini:
 	ttm_resource_fini(man, &vres->base);
@@ -604,7 +604,7 @@  static void amdgpu_vram_mgr_del(struct ttm_resource_manager *man,
 
 	amdgpu_vram_mgr_do_reserve(man);
 
-	drm_buddy_free_list(mm, &vres->blocks);
+	drm_buddy_free_list(mm, &vres->blocks, 0);
 	mutex_unlock(&mgr->lock);
 
 	atomic64_sub(vis_usage, &mgr->vis_usage);
@@ -912,7 +912,7 @@  void amdgpu_vram_mgr_fini(struct amdgpu_device *adev)
 		kfree(rsv);
 
 	list_for_each_entry_safe(rsv, temp, &mgr->reserved_pages, blocks) {
-		drm_buddy_free_list(&mgr->mm, &rsv->allocated);
+		drm_buddy_free_list(&mgr->mm, &rsv->allocated, 0);
 		kfree(rsv);
 	}
 	if (!adev->gmc.is_app_apu)
diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c
index c4222b886db7..625a30a6b855 100644
--- a/drivers/gpu/drm/drm_buddy.c
+++ b/drivers/gpu/drm/drm_buddy.c
@@ -38,8 +38,8 @@  static void drm_block_free(struct drm_buddy *mm,
 	kmem_cache_free(slab_blocks, block);
 }
 
-static void list_insert_sorted(struct drm_buddy *mm,
-			       struct drm_buddy_block *block)
+static void list_insert(struct drm_buddy *mm,
+			struct drm_buddy_block *block)
 {
 	struct drm_buddy_block *node;
 	struct list_head *head;
@@ -57,6 +57,16 @@  static void list_insert_sorted(struct drm_buddy *mm,
 	__list_add(&block->link, node->link.prev, &node->link);
 }
 
+static void clear_reset(struct drm_buddy_block *block)
+{
+	block->header &= ~DRM_BUDDY_HEADER_CLEAR;
+}
+
+static void mark_cleared(struct drm_buddy_block *block)
+{
+	block->header |= DRM_BUDDY_HEADER_CLEAR;
+}
+
 static void mark_allocated(struct drm_buddy_block *block)
 {
 	block->header &= ~DRM_BUDDY_HEADER_STATE;
@@ -71,7 +81,7 @@  static void mark_free(struct drm_buddy *mm,
 	block->header &= ~DRM_BUDDY_HEADER_STATE;
 	block->header |= DRM_BUDDY_FREE;
 
-	list_insert_sorted(mm, block);
+	list_insert(mm, block);
 }
 
 static void mark_split(struct drm_buddy_block *block)
@@ -82,6 +92,114 @@  static void mark_split(struct drm_buddy_block *block)
 	list_del(&block->link);
 }
 
+static struct drm_buddy_block *
+__get_buddy(struct drm_buddy_block *block)
+{
+	struct drm_buddy_block *parent;
+
+	parent = block->parent;
+	if (!parent)
+		return NULL;
+
+	if (parent->left == block)
+		return parent->right;
+
+	return parent->left;
+}
+
+static unsigned int __drm_buddy_free(struct drm_buddy *mm,
+				     struct drm_buddy_block *block,
+				     bool force_merge)
+{
+	struct drm_buddy_block *parent;
+	unsigned int order;
+
+	while ((parent = block->parent)) {
+		struct drm_buddy_block *buddy;
+
+		buddy = __get_buddy(block);
+
+		if (!drm_buddy_block_is_free(buddy))
+			break;
+
+		if (!force_merge) {
+			/**
+			 * Check the block and its buddy clear state and exit
+			 * the loop if they both have the dissimilar state.
+			 */
+			if (drm_buddy_block_is_clear(block) !=
+			    drm_buddy_block_is_clear(buddy))
+				break;
+
+			if (drm_buddy_block_is_clear(block))
+				mark_cleared(parent);
+		}
+
+		list_del(&buddy->link);
+		if (force_merge && drm_buddy_block_is_clear(buddy))
+			mm->clear_avail -= drm_buddy_block_size(mm, buddy);
+
+		drm_block_free(mm, block);
+		drm_block_free(mm, buddy);
+
+		block = parent;
+	}
+
+	order = drm_buddy_block_order(block);
+	mark_free(mm, block);
+
+	return order;
+}
+
+static int __force_merge(struct drm_buddy *mm,
+			 unsigned int min_order)
+{
+	unsigned int order;
+	int i;
+
+	if (!min_order)
+		return -ENOMEM;
+
+	if (min_order > mm->max_order)
+		return -EINVAL;
+
+	for (i = min_order - 1; i >= 0; i--) {
+		struct drm_buddy_block *block, *prev;
+
+		list_for_each_entry_safe_reverse(block, prev, &mm->free_list[i], link) {
+			struct drm_buddy_block *buddy;
+
+			if (!block->parent)
+				continue;
+
+			buddy = __get_buddy(block);
+			if (!drm_buddy_block_is_free(buddy))
+				continue;
+
+			WARN_ON(drm_buddy_block_is_clear(block) ==
+				drm_buddy_block_is_clear(buddy));
+
+			/**
+			 * If the prev block is same as buddy, don't access the
+			 * block in the next iteration as we would free the
+			 * buddy block as part of the free function.
+			 */
+			if (prev == buddy)
+				prev = list_prev_entry(prev, link);
+
+			list_del(&block->link);
+			if (drm_buddy_block_is_clear(block))
+				mm->clear_avail -= drm_buddy_block_size(mm, block);
+
+			order = __drm_buddy_free(mm, block, true);
+			if (order >= min_order)
+				return 0;
+		}
+	}
+
+	return -ENOMEM;
+}
+
 /**
  * drm_buddy_init - init memory manager
  *
@@ -137,7 +255,7 @@  int drm_buddy_init(struct drm_buddy *mm, u64 size, u64 chunk_size)
 	offset = 0;
 	i = 0;
 
-	/*
+	/**
 	 * Split into power-of-two blocks, in case we are given a size that is
 	 * not itself a power-of-two.
 	 */
@@ -186,11 +304,21 @@  EXPORT_SYMBOL(drm_buddy_init);
  */
 void drm_buddy_fini(struct drm_buddy *mm)
 {
+	u64 root_size, size;
+	unsigned int order;
 	int i;
 
+	size = mm->size;
+
 	for (i = 0; i < mm->n_roots; ++i) {
+		order = ilog2(size) - ilog2(mm->chunk_size);
+		__force_merge(mm, order);
+
 		WARN_ON(!drm_buddy_block_is_free(mm->roots[i]));
 		drm_block_free(mm, mm->roots[i]);
+
+		root_size = mm->chunk_size << order;
+		size -= root_size;
 	}
 
 	WARN_ON(mm->avail != mm->size);
@@ -223,26 +351,17 @@  static int split_block(struct drm_buddy *mm,
 	mark_free(mm, block->left);
 	mark_free(mm, block->right);
 
+	if (drm_buddy_block_is_clear(block)) {
+		mark_cleared(block->left);
+		mark_cleared(block->right);
+		clear_reset(block);
+	}
+
 	mark_split(block);
 
 	return 0;
 }
 
-static struct drm_buddy_block *
-__get_buddy(struct drm_buddy_block *block)
-{
-	struct drm_buddy_block *parent;
-
-	parent = block->parent;
-	if (!parent)
-		return NULL;
-
-	if (parent->left == block)
-		return parent->right;
-
-	return parent->left;
-}
-
 /**
  * drm_get_buddy - get buddy address
  *
@@ -260,30 +379,6 @@  drm_get_buddy(struct drm_buddy_block *block)
 }
 EXPORT_SYMBOL(drm_get_buddy);
 
-static void __drm_buddy_free(struct drm_buddy *mm,
-			     struct drm_buddy_block *block)
-{
-	struct drm_buddy_block *parent;
-
-	while ((parent = block->parent)) {
-		struct drm_buddy_block *buddy;
-
-		buddy = __get_buddy(block);
-
-		if (!drm_buddy_block_is_free(buddy))
-			break;
-
-		list_del(&buddy->link);
-
-		drm_block_free(mm, block);
-		drm_block_free(mm, buddy);
-
-		block = parent;
-	}
-
-	mark_free(mm, block);
-}
-
 /**
  * drm_buddy_free_block - free a block
  *
@@ -295,26 +390,59 @@  void drm_buddy_free_block(struct drm_buddy *mm,
 {
 	BUG_ON(!drm_buddy_block_is_allocated(block));
 	mm->avail += drm_buddy_block_size(mm, block);
-	__drm_buddy_free(mm, block);
+	if (drm_buddy_block_is_clear(block))
+		mm->clear_avail += drm_buddy_block_size(mm, block);
+
+	__drm_buddy_free(mm, block, false);
 }
 EXPORT_SYMBOL(drm_buddy_free_block);
 
-/**
- * drm_buddy_free_list - free blocks
- *
- * @mm: DRM buddy manager
- * @objects: input list head to free blocks
- */
-void drm_buddy_free_list(struct drm_buddy *mm, struct list_head *objects)
+static void __drm_buddy_free_list(struct drm_buddy *mm,
+				  struct list_head *objects,
+				  bool mark_clear,
+				  bool mark_dirty)
 {
 	struct drm_buddy_block *block, *on;
 
+	WARN_ON(mark_dirty && mark_clear);
+
 	list_for_each_entry_safe(block, on, objects, link) {
+		if (mark_clear)
+			mark_cleared(block);
+		else if (mark_dirty)
+			clear_reset(block);
 		drm_buddy_free_block(mm, block);
 		cond_resched();
 	}
 	INIT_LIST_HEAD(objects);
 }
+
+static void drm_buddy_free_list_internal(struct drm_buddy *mm,
+					 struct list_head *objects)
+{
+	/**
+	 * Don't touch the clear/dirty bit, since allocation is still internal
+	 * at this point. For example we might have just failed part of the
+	 * allocation.
+	 */
+	__drm_buddy_free_list(mm, objects, false, false);
+}
+
+/**
+ * drm_buddy_free_list - free blocks
+ *
+ * @mm: DRM buddy manager
+ * @objects: input list head to free blocks
+ * @flags: optional flags like DRM_BUDDY_CLEARED
+ */
+void drm_buddy_free_list(struct drm_buddy *mm,
+			 struct list_head *objects,
+			 unsigned int flags)
+{
+	bool mark_clear = flags & DRM_BUDDY_CLEARED;
+
+	__drm_buddy_free_list(mm, objects, mark_clear, !mark_clear);
+}
 EXPORT_SYMBOL(drm_buddy_free_list);
 
 static inline bool overlaps(u64 s1, u64 e1, u64 s2, u64 e2)
@@ -327,10 +455,19 @@  static inline bool contains(u64 s1, u64 e1, u64 s2, u64 e2)
 	return s1 <= s2 && e1 >= e2;
 }
 
+static bool block_incompatible(struct drm_buddy_block *block, unsigned int flags)
+{
+	bool needs_clear = flags & DRM_BUDDY_CLEAR_ALLOCATION;
+
+	return needs_clear != drm_buddy_block_is_clear(block);
+}
+
 static struct drm_buddy_block *
-alloc_range_bias(struct drm_buddy *mm,
-		 u64 start, u64 end,
-		 unsigned int order)
+__alloc_range_bias(struct drm_buddy *mm,
+		   u64 start, u64 end,
+		   unsigned int order,
+		   unsigned long flags,
+		   bool fallback)
 {
 	struct drm_buddy_block *block;
 	struct drm_buddy_block *buddy;
@@ -369,7 +506,10 @@  alloc_range_bias(struct drm_buddy *mm,
 
 		if (contains(start, end, block_start, block_end) &&
 		    order == drm_buddy_block_order(block)) {
-			/*
+			if (!fallback && block_incompatible(block, flags))
+				continue;
+
+			/**
 			 * Find the free block within the range.
 			 */
 			if (drm_buddy_block_is_free(block))
@@ -391,7 +531,7 @@  alloc_range_bias(struct drm_buddy *mm,
 	return ERR_PTR(-ENOSPC);
 
 err_undo:
-	/*
+	/**
 	 * We really don't want to leave around a bunch of split blocks, since
 	 * bigger is better, so make sure we merge everything back before we
 	 * free the allocated blocks.
@@ -400,30 +540,57 @@  alloc_range_bias(struct drm_buddy *mm,
 	if (buddy &&
 	    (drm_buddy_block_is_free(block) &&
 	     drm_buddy_block_is_free(buddy)))
-		__drm_buddy_free(mm, block);
+		__drm_buddy_free(mm, block, false);
 	return ERR_PTR(err);
 }
 
 static struct drm_buddy_block *
-get_maxblock(struct drm_buddy *mm, unsigned int order)
+__drm_buddy_alloc_range_bias(struct drm_buddy *mm,
+			     u64 start, u64 end,
+			     unsigned int order,
+			     unsigned long flags)
+{
+	struct drm_buddy_block *block;
+	bool fallback = false;
+
+	block = __alloc_range_bias(mm, start, end, order,
+				   flags, fallback);
+	if (IS_ERR(block) && mm->clear_avail)
+		return __alloc_range_bias(mm, start, end, order,
+					  flags, !fallback);
+
+	return block;
+}
+
+static struct drm_buddy_block *
+get_maxblock(struct drm_buddy *mm, unsigned int order,
+	     unsigned long flags)
 {
-	struct drm_buddy_block *max_block = NULL, *node;
+	struct drm_buddy_block *max_block = NULL, *block = NULL;
 	unsigned int i;
 
 	for (i = order; i <= mm->max_order; ++i) {
-		if (!list_empty(&mm->free_list[i])) {
-			node = list_last_entry(&mm->free_list[i],
-					       struct drm_buddy_block,
-					       link);
-			if (!max_block) {
-				max_block = node;
+		struct drm_buddy_block *tmp_block;
+
+		list_for_each_entry_reverse(tmp_block, &mm->free_list[i], link) {
+			if (block_incompatible(tmp_block, flags))
 				continue;
-			}
 
-			if (drm_buddy_block_offset(node) >
-			    drm_buddy_block_offset(max_block)) {
-				max_block = node;
-			}
+			block = tmp_block;
+			break;
+		}
+
+		if (!block)
+			continue;
+
+		if (!max_block) {
+			max_block = block;
+			continue;
+		}
+
+		if (drm_buddy_block_offset(block) >
+		    drm_buddy_block_offset(max_block)) {
+			max_block = block;
 		}
 	}
 
@@ -440,11 +607,29 @@  alloc_from_freelist(struct drm_buddy *mm,
 	int err;
 
 	if (flags & DRM_BUDDY_TOPDOWN_ALLOCATION) {
-		block = get_maxblock(mm, order);
+		block = get_maxblock(mm, order, flags);
 		if (block)
 			/* Store the obtained block order */
 			tmp = drm_buddy_block_order(block);
 	} else {
+		for (tmp = order; tmp <= mm->max_order; ++tmp) {
+			struct drm_buddy_block *tmp_block;
+
+			list_for_each_entry_reverse(tmp_block, &mm->free_list[tmp], link) {
+				if (block_incompatible(tmp_block, flags))
+					continue;
+
+				block = tmp_block;
+				break;
+			}
+
+			if (block)
+				break;
+		}
+	}
+
+	if (!block) {
+		/* Fallback method */
 		for (tmp = order; tmp <= mm->max_order; ++tmp) {
 			if (!list_empty(&mm->free_list[tmp])) {
 				block = list_last_entry(&mm->free_list[tmp],
@@ -454,10 +639,10 @@  alloc_from_freelist(struct drm_buddy *mm,
 					break;
 			}
 		}
-	}
 
-	if (!block)
-		return ERR_PTR(-ENOSPC);
+		if (!block)
+			return ERR_PTR(-ENOSPC);
+	}
 
 	BUG_ON(!drm_buddy_block_is_free(block));
 
@@ -473,7 +658,7 @@  alloc_from_freelist(struct drm_buddy *mm,
 
 err_undo:
 	if (tmp != order)
-		__drm_buddy_free(mm, block);
+		__drm_buddy_free(mm, block, false);
 	return ERR_PTR(err);
 }
 
@@ -524,6 +709,8 @@  static int __alloc_range(struct drm_buddy *mm,
 			mark_allocated(block);
 			total_allocated += drm_buddy_block_size(mm, block);
 			mm->avail -= drm_buddy_block_size(mm, block);
+			if (drm_buddy_block_is_clear(block))
+				mm->clear_avail -= drm_buddy_block_size(mm, block);
 			list_add_tail(&block->link, &allocated);
 			continue;
 		}
@@ -548,7 +735,7 @@  static int __alloc_range(struct drm_buddy *mm,
 	return 0;
 
 err_undo:
-	/*
+	/**
 	 * We really don't want to leave around a bunch of split blocks, since
 	 * bigger is better, so make sure we merge everything back before we
 	 * free the allocated blocks.
@@ -557,14 +744,14 @@  static int __alloc_range(struct drm_buddy *mm,
 	if (buddy &&
 	    (drm_buddy_block_is_free(block) &&
 	     drm_buddy_block_is_free(buddy)))
-		__drm_buddy_free(mm, block);
+		__drm_buddy_free(mm, block, false);
 
 err_free:
 	if (err == -ENOSPC && total_allocated_on_err) {
 		list_splice_tail(&allocated, blocks);
 		*total_allocated_on_err = total_allocated;
 	} else {
-		drm_buddy_free_list(mm, &allocated);
+		drm_buddy_free_list_internal(mm, &allocated);
 	}
 
 	return err;
@@ -630,11 +817,11 @@  static int __alloc_contig_try_harder(struct drm_buddy *mm,
 			list_splice(&blocks_lhs, blocks);
 			return 0;
 		} else if (err != -ENOSPC) {
-			drm_buddy_free_list(mm, blocks);
+			drm_buddy_free_list_internal(mm, blocks);
 			return err;
 		}
 		/* Free blocks for the next iteration */
-		drm_buddy_free_list(mm, blocks);
+		drm_buddy_free_list_internal(mm, blocks);
 	}
 
 	return -ENOSPC;
@@ -690,6 +877,8 @@  int drm_buddy_block_trim(struct drm_buddy *mm,
 	list_del(&block->link);
 	mark_free(mm, block);
 	mm->avail += drm_buddy_block_size(mm, block);
+	if (drm_buddy_block_is_clear(block))
+		mm->clear_avail += drm_buddy_block_size(mm, block);
 
 	/* Prevent recursively freeing this node */
 	parent = block->parent;
@@ -701,6 +890,8 @@  int drm_buddy_block_trim(struct drm_buddy *mm,
 	if (err) {
 		mark_allocated(block);
 		mm->avail -= drm_buddy_block_size(mm, block);
+		if (drm_buddy_block_is_clear(block))
+			mm->clear_avail -= drm_buddy_block_size(mm, block);
 		list_add(&block->link, blocks);
 	}
 
@@ -709,13 +900,28 @@  int drm_buddy_block_trim(struct drm_buddy *mm,
 }
 EXPORT_SYMBOL(drm_buddy_block_trim);
 
+static struct drm_buddy_block *
+__drm_buddy_alloc_blocks(struct drm_buddy *mm,
+			 u64 start, u64 end,
+			 unsigned int order,
+			 unsigned long flags)
+{
+	if (flags & DRM_BUDDY_RANGE_ALLOCATION)
+		/* Allocate traversing within the range */
+		return  __drm_buddy_alloc_range_bias(mm, start, end,
+						     order, flags);
+	else
+		/* Allocate from freelist */
+		return alloc_from_freelist(mm, order, flags);
+}
+
 /**
  * drm_buddy_alloc_blocks - allocate power-of-two blocks
  *
  * @mm: DRM buddy manager to allocate from
  * @start: start of the allowed range for this block
  * @end: end of the allowed range for this block
- * @size: size of the allocation
+ * @size: size of the allocation in bytes
  * @min_block_size: alignment of the allocation
  * @blocks: output list head to add allocated blocks
  * @flags: DRM_BUDDY_*_ALLOCATION flags
@@ -761,8 +967,18 @@  int drm_buddy_alloc_blocks(struct drm_buddy *mm,
 		return -EINVAL;
 
 	/* Actual range allocation */
-	if (start + size == end)
-		return __drm_buddy_alloc_range(mm, start, size, NULL, blocks);
+	if (start + size == end) {
+		err =  __drm_buddy_alloc_range(mm, start, size, NULL, blocks);
+		if (err) {
+			order = ilog2(size) - ilog2(mm->chunk_size);
+			if (mm->clear_avail && !__force_merge(mm, order))
+				return __drm_buddy_alloc_range(mm, start, size, NULL, blocks);
+
+			return err;
+		}
+
+		return err;
+	}
 
 	original_size = size;
 	original_min_size = min_block_size;
@@ -786,23 +1002,34 @@  int drm_buddy_alloc_blocks(struct drm_buddy *mm,
 		BUG_ON(order < min_order);
 
 		do {
-			if (flags & DRM_BUDDY_RANGE_ALLOCATION)
-				/* Allocate traversing within the range */
-				block = alloc_range_bias(mm, start, end, order);
-			else
-				/* Allocate from freelist */
-				block = alloc_from_freelist(mm, order, flags);
-
+			block = __drm_buddy_alloc_blocks(mm, start,
+							 end,
+							 order,
+							 flags);
 			if (!IS_ERR(block))
 				break;
 
 			if (order-- == min_order) {
+				/**
+				 * Try allocation through force merge method
+				 */
+				if (mm->clear_avail && !__force_merge(mm, min_order)) {
+					block = __drm_buddy_alloc_blocks(mm, start,
+									 end,
+									 min_order,
+									 flags);
+					if (!IS_ERR(block)) {
+						order = min_order;
+						break;
+					}
+				}
+
+				/**
+				 * Try contiguous block allocation through
+				 * try harder method.
+				 */
 				if (flags & DRM_BUDDY_CONTIGUOUS_ALLOCATION &&
 				    !(flags & DRM_BUDDY_RANGE_ALLOCATION))
-					/*
-					 * Try contiguous block allocation through
-					 * try harder method
-					 */
 					return __alloc_contig_try_harder(mm,
 									 original_size,
 									 original_min_size,
@@ -814,6 +1041,8 @@  int drm_buddy_alloc_blocks(struct drm_buddy *mm,
 
 		mark_allocated(block);
 		mm->avail -= drm_buddy_block_size(mm, block);
+		if (drm_buddy_block_is_clear(block))
+			mm->clear_avail -= drm_buddy_block_size(mm, block);
 		kmemleak_update_trace(block);
 		list_add_tail(&block->link, &allocated);
 
@@ -823,7 +1052,9 @@  int drm_buddy_alloc_blocks(struct drm_buddy *mm,
 			break;
 	} while (1);
 
-	/* Trim the allocated block to the required size */
+	/**
+	 * Trim the allocated block to the required size
+	 */
 	if (original_size != size) {
 		struct list_head *trim_list;
 		LIST_HEAD(temp);
@@ -852,7 +1083,7 @@  int drm_buddy_alloc_blocks(struct drm_buddy *mm,
 	return 0;
 
 err_free:
-	drm_buddy_free_list(mm, &allocated);
+	drm_buddy_free_list_internal(mm, &allocated);
 	return err;
 }
 EXPORT_SYMBOL(drm_buddy_alloc_blocks);
@@ -885,8 +1116,8 @@  void drm_buddy_print(struct drm_buddy *mm, struct drm_printer *p)
 {
 	int order;
 
-	drm_printf(p, "chunk_size: %lluKiB, total: %lluMiB, free: %lluMiB\n",
-		   mm->chunk_size >> 10, mm->size >> 20, mm->avail >> 20);
+	drm_printf(p, "chunk_size: %lluKiB, total: %lluMiB, free: %lluMiB, clear_free: %lluMiB\n",
+		   mm->chunk_size >> 10, mm->size >> 20, mm->avail >> 20, mm->clear_avail >> 20);
 
 	for (order = mm->max_order; order >= 0; order--) {
 		struct drm_buddy_block *block;
diff --git a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
index 0d735d5c2b35..942345548bc3 100644
--- a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
+++ b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
@@ -126,7 +126,7 @@  static int i915_ttm_buddy_man_alloc(struct ttm_resource_manager *man,
 	return 0;
 
 err_free_blocks:
-	drm_buddy_free_list(mm, &bman_res->blocks);
+	drm_buddy_free_list(mm, &bman_res->blocks, 0);
 	mutex_unlock(&bman->lock);
 err_free_res:
 	ttm_resource_fini(man, &bman_res->base);
@@ -141,7 +141,7 @@  static void i915_ttm_buddy_man_free(struct ttm_resource_manager *man,
 	struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
 
 	mutex_lock(&bman->lock);
-	drm_buddy_free_list(&bman->mm, &bman_res->blocks);
+	drm_buddy_free_list(&bman->mm, &bman_res->blocks, 0);
 	bman->visible_avail += bman_res->used_visible_size;
 	mutex_unlock(&bman->lock);
 
@@ -345,7 +345,7 @@  int i915_ttm_buddy_man_fini(struct ttm_device *bdev, unsigned int type)
 	ttm_set_driver_manager(bdev, type, NULL);
 
 	mutex_lock(&bman->lock);
-	drm_buddy_free_list(mm, &bman->reserved);
+	drm_buddy_free_list(mm, &bman->reserved, 0);
 	drm_buddy_fini(mm);
 	bman->visible_avail += bman->visible_reserved;
 	WARN_ON_ONCE(bman->visible_avail != bman->visible_size);
diff --git a/drivers/gpu/drm/tests/drm_buddy_test.c b/drivers/gpu/drm/tests/drm_buddy_test.c
index 2f32fb2f12e7..454ad9952f56 100644
--- a/drivers/gpu/drm/tests/drm_buddy_test.c
+++ b/drivers/gpu/drm/tests/drm_buddy_test.c
@@ -64,7 +64,7 @@  static void drm_test_buddy_alloc_contiguous(struct kunit *test)
 							   DRM_BUDDY_CONTIGUOUS_ALLOCATION),
 			       "buddy_alloc didn't error size=%u\n", 3 * ps);
 
-	drm_buddy_free_list(&mm, &middle);
+	drm_buddy_free_list(&mm, &middle, 0);
 	KUNIT_ASSERT_TRUE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
 							   3 * ps, ps, &allocated,
 							   DRM_BUDDY_CONTIGUOUS_ALLOCATION),
@@ -74,7 +74,7 @@  static void drm_test_buddy_alloc_contiguous(struct kunit *test)
 							   DRM_BUDDY_CONTIGUOUS_ALLOCATION),
 			       "buddy_alloc didn't error size=%u\n", 2 * ps);
 
-	drm_buddy_free_list(&mm, &right);
+	drm_buddy_free_list(&mm, &right, 0);
 	KUNIT_ASSERT_TRUE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
 							   3 * ps, ps, &allocated,
 							   DRM_BUDDY_CONTIGUOUS_ALLOCATION),
@@ -89,7 +89,7 @@  static void drm_test_buddy_alloc_contiguous(struct kunit *test)
 							    DRM_BUDDY_CONTIGUOUS_ALLOCATION),
 			       "buddy_alloc hit an error size=%u\n", 2 * ps);
 
-	drm_buddy_free_list(&mm, &left);
+	drm_buddy_free_list(&mm, &left, 0);
 	KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
 							    3 * ps, ps, &allocated,
 							    DRM_BUDDY_CONTIGUOUS_ALLOCATION),
@@ -101,7 +101,7 @@  static void drm_test_buddy_alloc_contiguous(struct kunit *test)
 
 	KUNIT_ASSERT_EQ(test, total, ps * 2 + ps * 3);
 
-	drm_buddy_free_list(&mm, &allocated);
+	drm_buddy_free_list(&mm, &allocated, 0);
 	drm_buddy_fini(&mm);
 }
 
@@ -170,7 +170,7 @@  static void drm_test_buddy_alloc_pathological(struct kunit *test)
 							  top, max_order);
 	}
 
-	drm_buddy_free_list(&mm, &holes);
+	drm_buddy_free_list(&mm, &holes, 0);
 
 	/* Nothing larger than blocks of chunk_size now available */
 	for (order = 1; order <= max_order; order++) {
@@ -182,7 +182,7 @@  static void drm_test_buddy_alloc_pathological(struct kunit *test)
 	}
 
 	list_splice_tail(&holes, &blocks);
-	drm_buddy_free_list(&mm, &blocks);
+	drm_buddy_free_list(&mm, &blocks, 0);
 	drm_buddy_fini(&mm);
 }
 
@@ -277,7 +277,7 @@  static void drm_test_buddy_alloc_pessimistic(struct kunit *test)
 
 	list_del(&block->link);
 	drm_buddy_free_block(&mm, block);
-	drm_buddy_free_list(&mm, &blocks);
+	drm_buddy_free_list(&mm, &blocks, 0);
 	drm_buddy_fini(&mm);
 }
 
@@ -323,7 +323,7 @@  static void drm_test_buddy_alloc_optimistic(struct kunit *test)
 							   size, size, &tmp, flags),
 						  "buddy_alloc unexpectedly succeeded, it should be full!");
 
-	drm_buddy_free_list(&mm, &blocks);
+	drm_buddy_free_list(&mm, &blocks, 0);
 	drm_buddy_fini(&mm);
 }
 
@@ -358,7 +358,7 @@  static void drm_test_buddy_alloc_limit(struct kunit *test)
 						drm_buddy_block_size(&mm, block),
 						BIT_ULL(mm.max_order) * PAGE_SIZE);
 
-	drm_buddy_free_list(&mm, &allocated);
+	drm_buddy_free_list(&mm, &allocated, 0);
 	drm_buddy_fini(&mm);
 }
 
diff --git a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
index 115ec745e502..1ad678b62c4a 100644
--- a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
+++ b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
@@ -196,7 +196,7 @@  static int xe_ttm_vram_mgr_new(struct ttm_resource_manager *man,
 	return 0;
 
 error_free_blocks:
-	drm_buddy_free_list(mm, &vres->blocks);
+	drm_buddy_free_list(mm, &vres->blocks, 0);
 	mutex_unlock(&mgr->lock);
 error_fini:
 	ttm_resource_fini(man, &vres->base);
@@ -214,7 +214,7 @@  static void xe_ttm_vram_mgr_del(struct ttm_resource_manager *man,
 	struct drm_buddy *mm = &mgr->mm;
 
 	mutex_lock(&mgr->lock);
-	drm_buddy_free_list(mm, &vres->blocks);
+	drm_buddy_free_list(mm, &vres->blocks, 0);
 	mgr->visible_avail += vres->used_visible_size;
 	mutex_unlock(&mgr->lock);
 
diff --git a/include/drm/drm_buddy.h b/include/drm/drm_buddy.h
index a5b39fc01003..82570f77e817 100644
--- a/include/drm/drm_buddy.h
+++ b/include/drm/drm_buddy.h
@@ -25,6 +25,8 @@ 
 #define DRM_BUDDY_RANGE_ALLOCATION		BIT(0)
 #define DRM_BUDDY_TOPDOWN_ALLOCATION		BIT(1)
 #define DRM_BUDDY_CONTIGUOUS_ALLOCATION		BIT(2)
+#define DRM_BUDDY_CLEAR_ALLOCATION		BIT(3)
+#define DRM_BUDDY_CLEARED			BIT(4)
 
 struct drm_buddy_block {
 #define DRM_BUDDY_HEADER_OFFSET GENMASK_ULL(63, 12)
@@ -32,8 +34,9 @@  struct drm_buddy_block {
 #define   DRM_BUDDY_ALLOCATED	   (1 << 10)
 #define   DRM_BUDDY_FREE	   (2 << 10)
 #define   DRM_BUDDY_SPLIT	   (3 << 10)
+#define DRM_BUDDY_HEADER_CLEAR  GENMASK_ULL(9, 9)
 /* Free to be used, if needed in the future */
-#define DRM_BUDDY_HEADER_UNUSED GENMASK_ULL(9, 6)
+#define DRM_BUDDY_HEADER_UNUSED GENMASK_ULL(8, 6)
 #define DRM_BUDDY_HEADER_ORDER  GENMASK_ULL(5, 0)
 	u64 header;
 
@@ -86,6 +89,7 @@  struct drm_buddy {
 	u64 chunk_size;
 	u64 size;
 	u64 avail;
+	u64 clear_avail;
 };
 
 static inline u64
@@ -112,6 +116,12 @@  drm_buddy_block_is_allocated(struct drm_buddy_block *block)
 	return drm_buddy_block_state(block) == DRM_BUDDY_ALLOCATED;
 }
 
+static inline bool
+drm_buddy_block_is_clear(struct drm_buddy_block *block)
+{
+	return block->header & DRM_BUDDY_HEADER_CLEAR;
+}
+
 static inline bool
 drm_buddy_block_is_free(struct drm_buddy_block *block)
 {
@@ -150,7 +160,9 @@  int drm_buddy_block_trim(struct drm_buddy *mm,
 
 void drm_buddy_free_block(struct drm_buddy *mm, struct drm_buddy_block *block);
 
-void drm_buddy_free_list(struct drm_buddy *mm, struct list_head *objects);
+void drm_buddy_free_list(struct drm_buddy *mm,
+			 struct list_head *objects,
+			 unsigned int flags);
 
 void drm_buddy_print(struct drm_buddy *mm, struct drm_printer *p);
 void drm_buddy_block_print(struct drm_buddy *mm,