diff mbox series

[5/5] mm: remove MIGRATE_SYNC_NO_COPY mode

Message ID 20240524052843.182275-6-wangkefeng.wang@huawei.com (mailing list archive)
State New
Headers show
Series mm: cleanup MIGRATE_SYNC_NO_COPY mode | expand

Commit Message

Kefeng Wang May 24, 2024, 5:28 a.m. UTC 
Commit 2916ecc0f9d4 ("mm/migrate: new migrate mode MIGRATE_SYNC_NO_COPY")
introduce a new MIGRATE_SYNC_NO_COPY mode to allow to offload the copy to
a device DMA engine, which is only used __migrate_device_pages() to decide
whether or not copy the old page, and the MIGRATE_SYNC_NO_COPY mode only
set in hmm, as the MIGRATE_SYNC_NO_COPY set is removed by previous cleanup,
it seems that we could remove the unnecessary MIGRATE_SYNC_NO_COPY.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 fs/aio.c                     | 12 +-----------
 fs/hugetlbfs/inode.c         |  5 +----
 include/linux/migrate_mode.h |  5 -----
 mm/balloon_compaction.c      |  8 --------
 mm/migrate.c                 |  8 +-------
 mm/zsmalloc.c                |  8 --------
 6 files changed, 3 insertions(+), 43 deletions(-)

Comments

Jane Chu June 7, 2024, 9:27 p.m. UTC | #1 
On 5/23/2024 10:28 PM, Kefeng Wang wrote:

> Commit 2916ecc0f9d4 ("mm/migrate: new migrate mode MIGRATE_SYNC_NO_COPY")
> introduce a new MIGRATE_SYNC_NO_COPY mode to allow to offload the copy to
> a device DMA engine, which is only used __migrate_device_pages() to decide
nit:  s/only used/only used in/
> whether or not copy the old page, and the MIGRATE_SYNC_NO_COPY mode only
s/copy/to copy/,  s/mode only set/mode is only set/
> set in hmm, as the MIGRATE_SYNC_NO_COPY set is removed by previous cleanup,
> it seems that we could remove the unnecessary MIGRATE_SYNC_NO_COPY.
>
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> ---
>   fs/aio.c                     | 12 +-----------
>   fs/hugetlbfs/inode.c         |  5 +----
>   include/linux/migrate_mode.h |  5 -----
>   mm/balloon_compaction.c      |  8 --------
>   mm/migrate.c                 |  8 +-------
>   mm/zsmalloc.c                |  8 --------
>   6 files changed, 3 insertions(+), 43 deletions(-)
>
> diff --git a/fs/aio.c b/fs/aio.c
> index 57c9f7c077e6..07ff8bbdcd2a 100644
> --- a/fs/aio.c
> +++ b/fs/aio.c
> @@ -410,17 +410,7 @@ static int aio_migrate_folio(struct address_space *mapping, struct folio *dst,
>   	struct kioctx *ctx;
>   	unsigned long flags;
>   	pgoff_t idx;
> -	int rc;
> -
> -	/*
> -	 * We cannot support the _NO_COPY case here, because copy needs to
> -	 * happen under the ctx->completion_lock. That does not work with the
> -	 * migration workflow of MIGRATE_SYNC_NO_COPY.
> -	 */
> -	if (mode == MIGRATE_SYNC_NO_COPY)
> -		return -EINVAL;
> -
> -	rc = 0;
> +	int rc = 0;
>   
>   	/* mapping->i_private_lock here protects against the kioctx teardown.  */
>   	spin_lock(&mapping->i_private_lock);
> diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
> index 412f295acebe..6df794ed4066 100644
> --- a/fs/hugetlbfs/inode.c
> +++ b/fs/hugetlbfs/inode.c
> @@ -1128,10 +1128,7 @@ static int hugetlbfs_migrate_folio(struct address_space *mapping,
>   		hugetlb_set_folio_subpool(src, NULL);
>   	}
>   
> -	if (mode != MIGRATE_SYNC_NO_COPY)
> -		folio_migrate_copy(dst, src);
> -	else
> -		folio_migrate_flags(dst, src);
> +	folio_migrate_copy(dst, src);
>   
>   	return MIGRATEPAGE_SUCCESS;
>   }
> diff --git a/include/linux/migrate_mode.h b/include/linux/migrate_mode.h
> index f37cc03f9369..9fb482bb7323 100644
> --- a/include/linux/migrate_mode.h
> +++ b/include/linux/migrate_mode.h
> @@ -7,16 +7,11 @@
>    *	on most operations but not ->writepage as the potential stall time
>    *	is too significant
>    * MIGRATE_SYNC will block when migrating pages
> - * MIGRATE_SYNC_NO_COPY will block when migrating pages but will not copy pages
> - *	with the CPU. Instead, page copy happens outside the migratepage()
> - *	callback and is likely using a DMA engine. See migrate_vma() and HMM
> - *	(mm/hmm.c) for users of this mode.
>    */
>   enum migrate_mode {
>   	MIGRATE_ASYNC,
>   	MIGRATE_SYNC_LIGHT,
>   	MIGRATE_SYNC,
> -	MIGRATE_SYNC_NO_COPY,
>   };
>   
>   enum migrate_reason {
> diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c
> index 22c96fed70b5..6597ebea8ae2 100644
> --- a/mm/balloon_compaction.c
> +++ b/mm/balloon_compaction.c
> @@ -234,14 +234,6 @@ static int balloon_page_migrate(struct page *newpage, struct page *page,
>   {
>   	struct balloon_dev_info *balloon = balloon_page_device(page);
>   
> -	/*
> -	 * We can not easily support the no copy case here so ignore it as it
> -	 * is unlikely to be used with balloon pages. See include/linux/hmm.h
> -	 * for a user of the MIGRATE_SYNC_NO_COPY mode.
> -	 */
> -	if (mode == MIGRATE_SYNC_NO_COPY)
> -		return -EINVAL;
> -
>   	VM_BUG_ON_PAGE(!PageLocked(page), page);
>   	VM_BUG_ON_PAGE(!PageLocked(newpage), newpage);
>   
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 1d1cb832fdb4..e04b451c4289 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -671,10 +671,7 @@ static int __migrate_folio(struct address_space *mapping, struct folio *dst,
>   	if (src_private)
>   		folio_attach_private(dst, folio_detach_private(src));
>   
> -	if (mode != MIGRATE_SYNC_NO_COPY)
> -		folio_migrate_copy(dst, src);
> -	else
> -		folio_migrate_flags(dst, src);
> +	folio_migrate_copy(dst, src);
>   	return MIGRATEPAGE_SUCCESS;
>   }
>   
> @@ -903,7 +900,6 @@ static int fallback_migrate_folio(struct address_space *mapping,
>   		/* Only writeback folios in full synchronous migration */
>   		switch (mode) {
>   		case MIGRATE_SYNC:
> -		case MIGRATE_SYNC_NO_COPY:
>   			break;
>   		default:
>   			return -EBUSY;
> @@ -1161,7 +1157,6 @@ static int migrate_folio_unmap(new_folio_t get_new_folio,
>   		 */
>   		switch (mode) {
>   		case MIGRATE_SYNC:
> -		case MIGRATE_SYNC_NO_COPY:
>   			break;
>   		default:
>   			rc = -EBUSY;
> @@ -1372,7 +1367,6 @@ static int unmap_and_move_huge_page(new_folio_t get_new_folio,
>   			goto out;
>   		switch (mode) {
>   		case MIGRATE_SYNC:
> -		case MIGRATE_SYNC_NO_COPY:
>   			break;
>   		default:
>   			goto out;
> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index b42d3545ca85..6e7967853477 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -1752,14 +1752,6 @@ static int zs_page_migrate(struct page *newpage, struct page *page,
>   	unsigned long old_obj, new_obj;
>   	unsigned int obj_idx;
>   
> -	/*
> -	 * We cannot support the _NO_COPY case here, because copy needs to
> -	 * happen under the zs lock, which does not work with
> -	 * MIGRATE_SYNC_NO_COPY workflow.
> -	 */
> -	if (mode == MIGRATE_SYNC_NO_COPY)
> -		return -EINVAL;
> -
>   	VM_BUG_ON_PAGE(!PageIsolated(page), page);
>   
>   	/* The page is locked, so this pointer must remain valid */

Except the nits above, patch looks good to me.

Reviewed-by: Jane Chu <jane.chu@oracle.com>

-jane
diff mbox series

Patch

diff --git a/fs/aio.c b/fs/aio.c
index 57c9f7c077e6..07ff8bbdcd2a 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -410,17 +410,7 @@  static int aio_migrate_folio(struct address_space *mapping, struct folio *dst,
 	struct kioctx *ctx;
 	unsigned long flags;
 	pgoff_t idx;
-	int rc;
-
-	/*
-	 * We cannot support the _NO_COPY case here, because copy needs to
-	 * happen under the ctx->completion_lock. That does not work with the
-	 * migration workflow of MIGRATE_SYNC_NO_COPY.
-	 */
-	if (mode == MIGRATE_SYNC_NO_COPY)
-		return -EINVAL;
-
-	rc = 0;
+	int rc = 0;
 
 	/* mapping->i_private_lock here protects against the kioctx teardown.  */
 	spin_lock(&mapping->i_private_lock);
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 412f295acebe..6df794ed4066 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -1128,10 +1128,7 @@  static int hugetlbfs_migrate_folio(struct address_space *mapping,
 		hugetlb_set_folio_subpool(src, NULL);
 	}
 
-	if (mode != MIGRATE_SYNC_NO_COPY)
-		folio_migrate_copy(dst, src);
-	else
-		folio_migrate_flags(dst, src);
+	folio_migrate_copy(dst, src);
 
 	return MIGRATEPAGE_SUCCESS;
 }
diff --git a/include/linux/migrate_mode.h b/include/linux/migrate_mode.h
index f37cc03f9369..9fb482bb7323 100644
--- a/include/linux/migrate_mode.h
+++ b/include/linux/migrate_mode.h
@@ -7,16 +7,11 @@ 
  *	on most operations but not ->writepage as the potential stall time
  *	is too significant
  * MIGRATE_SYNC will block when migrating pages
- * MIGRATE_SYNC_NO_COPY will block when migrating pages but will not copy pages
- *	with the CPU. Instead, page copy happens outside the migratepage()
- *	callback and is likely using a DMA engine. See migrate_vma() and HMM
- *	(mm/hmm.c) for users of this mode.
  */
 enum migrate_mode {
 	MIGRATE_ASYNC,
 	MIGRATE_SYNC_LIGHT,
 	MIGRATE_SYNC,
-	MIGRATE_SYNC_NO_COPY,
 };
 
 enum migrate_reason {
diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c
index 22c96fed70b5..6597ebea8ae2 100644
--- a/mm/balloon_compaction.c
+++ b/mm/balloon_compaction.c
@@ -234,14 +234,6 @@  static int balloon_page_migrate(struct page *newpage, struct page *page,
 {
 	struct balloon_dev_info *balloon = balloon_page_device(page);
 
-	/*
-	 * We can not easily support the no copy case here so ignore it as it
-	 * is unlikely to be used with balloon pages. See include/linux/hmm.h
-	 * for a user of the MIGRATE_SYNC_NO_COPY mode.
-	 */
-	if (mode == MIGRATE_SYNC_NO_COPY)
-		return -EINVAL;
-
 	VM_BUG_ON_PAGE(!PageLocked(page), page);
 	VM_BUG_ON_PAGE(!PageLocked(newpage), newpage);
 
diff --git a/mm/migrate.c b/mm/migrate.c
index 1d1cb832fdb4..e04b451c4289 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -671,10 +671,7 @@  static int __migrate_folio(struct address_space *mapping, struct folio *dst,
 	if (src_private)
 		folio_attach_private(dst, folio_detach_private(src));
 
-	if (mode != MIGRATE_SYNC_NO_COPY)
-		folio_migrate_copy(dst, src);
-	else
-		folio_migrate_flags(dst, src);
+	folio_migrate_copy(dst, src);
 	return MIGRATEPAGE_SUCCESS;
 }
 
@@ -903,7 +900,6 @@  static int fallback_migrate_folio(struct address_space *mapping,
 		/* Only writeback folios in full synchronous migration */
 		switch (mode) {
 		case MIGRATE_SYNC:
-		case MIGRATE_SYNC_NO_COPY:
 			break;
 		default:
 			return -EBUSY;
@@ -1161,7 +1157,6 @@  static int migrate_folio_unmap(new_folio_t get_new_folio,
 		 */
 		switch (mode) {
 		case MIGRATE_SYNC:
-		case MIGRATE_SYNC_NO_COPY:
 			break;
 		default:
 			rc = -EBUSY;
@@ -1372,7 +1367,6 @@  static int unmap_and_move_huge_page(new_folio_t get_new_folio,
 			goto out;
 		switch (mode) {
 		case MIGRATE_SYNC:
-		case MIGRATE_SYNC_NO_COPY:
 			break;
 		default:
 			goto out;
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index b42d3545ca85..6e7967853477 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -1752,14 +1752,6 @@  static int zs_page_migrate(struct page *newpage, struct page *page,
 	unsigned long old_obj, new_obj;
 	unsigned int obj_idx;
 
-	/*
-	 * We cannot support the _NO_COPY case here, because copy needs to
-	 * happen under the zs lock, which does not work with
-	 * MIGRATE_SYNC_NO_COPY workflow.
-	 */
-	if (mode == MIGRATE_SYNC_NO_COPY)
-		return -EINVAL;
-
 	VM_BUG_ON_PAGE(!PageIsolated(page), page);
 
 	/* The page is locked, so this pointer must remain valid */