| Message ID | 20221204013046.154960-3-bhe@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/vmalloc.c: allow vread() to read out vm_map_ram areas | expand |
> Through vmalloc API, a virtual kernel area is reserved for physical > address mapping. And vmap_area is used to track them, while vm_struct > is allocated to associate with the vmap_area to store more information > and passed out. > > However, area reserved via vm_map_ram() is an exception. It doesn't have > vm_struct to associate with vmap_area. And we can't recognize the > vmap_area with '->vm == NULL' as a vm_map_ram() area because the normal > freeing path will set va->vm = NULL before unmapping, please see > function remove_vm_area(). > > Meanwhile, there are two types of vm_map_ram area. One is the whole > vmap_area being reserved and mapped at one time; the other is the > whole vmap_area with VMAP_BLOCK_SIZE size being reserved, while mapped > into split regions with smaller size several times via vb_alloc(). > > To mark the area reserved through vm_map_ram(), add flags field into > struct vmap_area. Bit 0 indicates whether it's a vm_map_ram area, > while bit 1 indicates whether it's a vmap_block type of vm_map_ram > area. > > This is a preparatoin for later use. > > Signed-off-by: Baoquan He <bhe@redhat.com> > --- > include/linux/vmalloc.h | 1 + > mm/vmalloc.c | 18 +++++++++++++++++- > 2 files changed, 18 insertions(+), 1 deletion(-) > > diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h > index 096d48aa3437..69250efa03d1 100644 > --- a/include/linux/vmalloc.h > +++ b/include/linux/vmalloc.h > @@ -76,6 +76,7 @@ struct vmap_area { > unsigned long subtree_max_size; /* in "free" tree */ > struct vm_struct *vm; /* in "busy" tree */ > }; > + unsigned long flags; /* mark type of vm_map_ram area */ > }; > > /* archs that select HAVE_ARCH_HUGE_VMAP should override one or more of these */ > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 5d3fd3e6fe09..d6f376060d83 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -1815,6 +1815,7 @@ static void free_vmap_area_noflush(struct vmap_area *va) > > spin_lock(&vmap_area_lock); > unlink_va(va, &vmap_area_root); > + va->flags = 0; > spin_unlock(&vmap_area_lock); > This is not a good place to set flags to zero. It looks to me like corner and kind of specific. > nr_lazy = atomic_long_add_return((va->va_end - va->va_start) >> > @@ -1887,6 +1888,10 @@ struct vmap_area *find_vmap_area(unsigned long addr) > > #define VMAP_BLOCK_SIZE (VMAP_BBMAP_BITS * PAGE_SIZE) > > +#define VMAP_RAM 0x1 > +#define VMAP_BLOCK 0x2 > +#define VMAP_FLAGS_MASK 0x3 > + > struct vmap_block_queue { > spinlock_t lock; > struct list_head free; > @@ -1967,6 +1972,9 @@ static void *new_vmap_block(unsigned int order, gfp_t gfp_mask) > kfree(vb); > return ERR_CAST(va); > } > + spin_lock(&vmap_area_lock); > + va->flags = VMAP_RAM|VMAP_BLOCK; > + spin_unlock(&vmap_area_lock); > The per-cpu code was created as a fast per-cpu allocator because of high vmalloc lock contention. If possible we should avoid of locking of the vmap_area_lock. Because it has a high contention. > > vaddr = vmap_block_vaddr(va->va_start, 0); > spin_lock_init(&vb->lock); > @@ -2229,8 +2237,12 @@ void vm_unmap_ram(const void *mem, unsigned int count) > return; > } > > - va = find_vmap_area(addr); > + spin_lock(&vmap_area_lock); > + va = __find_vmap_area((unsigned long)addr, &vmap_area_root); > BUG_ON(!va); > + if (va) > + va->flags &= ~VMAP_RAM; > + spin_unlock(&vmap_area_lock); > debug_check_no_locks_freed((void *)va->va_start, > (va->va_end - va->va_start)); > free_unmap_vmap_area(va); > @@ -2269,6 +2281,10 @@ void *vm_map_ram(struct page **pages, unsigned int count, int node) > if (IS_ERR(va)) > return NULL; > > + spin_lock(&vmap_area_lock); > + va->flags = VMAP_RAM; > + spin_unlock(&vmap_area_lock); > + > Same here. -- Uladzislau Rezki
On 12/05/22 at 01:56pm, Uladzislau Rezki wrote: > > Through vmalloc API, a virtual kernel area is reserved for physical > > address mapping. And vmap_area is used to track them, while vm_struct > > is allocated to associate with the vmap_area to store more information > > and passed out. > > > > However, area reserved via vm_map_ram() is an exception. It doesn't have > > vm_struct to associate with vmap_area. And we can't recognize the > > vmap_area with '->vm == NULL' as a vm_map_ram() area because the normal > > freeing path will set va->vm = NULL before unmapping, please see > > function remove_vm_area(). > > > > Meanwhile, there are two types of vm_map_ram area. One is the whole > > vmap_area being reserved and mapped at one time; the other is the > > whole vmap_area with VMAP_BLOCK_SIZE size being reserved, while mapped > > into split regions with smaller size several times via vb_alloc(). > > > > To mark the area reserved through vm_map_ram(), add flags field into > > struct vmap_area. Bit 0 indicates whether it's a vm_map_ram area, > > while bit 1 indicates whether it's a vmap_block type of vm_map_ram > > area. > > > > This is a preparatoin for later use. > > > > Signed-off-by: Baoquan He <bhe@redhat.com> > > --- > > include/linux/vmalloc.h | 1 + > > mm/vmalloc.c | 18 +++++++++++++++++- > > 2 files changed, 18 insertions(+), 1 deletion(-) > > > > diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h > > index 096d48aa3437..69250efa03d1 100644 > > --- a/include/linux/vmalloc.h > > +++ b/include/linux/vmalloc.h > > @@ -76,6 +76,7 @@ struct vmap_area { > > unsigned long subtree_max_size; /* in "free" tree */ > > struct vm_struct *vm; /* in "busy" tree */ > > }; > > + unsigned long flags; /* mark type of vm_map_ram area */ > > }; > > > > /* archs that select HAVE_ARCH_HUGE_VMAP should override one or more of these */ > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > > index 5d3fd3e6fe09..d6f376060d83 100644 > > --- a/mm/vmalloc.c > > +++ b/mm/vmalloc.c > > @@ -1815,6 +1815,7 @@ static void free_vmap_area_noflush(struct vmap_area *va) > > > > spin_lock(&vmap_area_lock); > > unlink_va(va, &vmap_area_root); > > + va->flags = 0; > > spin_unlock(&vmap_area_lock); > > > This is not a good place to set flags to zero. It looks to me like > corner and kind of specific. Thanks for reviewing. Here, I thought to clear VMAP_RAM|VMAP_BLOCK on vmap->flags when free the vmap_block. I didn't find a good place to do the clearing. When we call free_vmap_block(), we either come from purge_fragmented_blocks(), or from vb_free(). In vb_free(), it will call free_vmap_block() when the whole vmap_block is dirty. In purge_fragmented_blocks(), it will try to purge all vmap_block which only has dirty or free regions. For both of above functions, they will call free_vmap_block() when there's no being used region in the vmap_block. purge_fragmented_blocks() vb_free() -->free_vmap_block() So seems we don't need to clear the VMAP_RAM|VMAP_BLOCK on vmap->flags because there's no mapping existed in the vmap_block. The consequent free_vmap_block() will remove the relevant vmap_area from vmap_area_list and vmap_area_root tree. So I plan to remove code change in this place. > > > > nr_lazy = atomic_long_add_return((va->va_end - va->va_start) >> > > @@ -1887,6 +1888,10 @@ struct vmap_area *find_vmap_area(unsigned long addr) > > > > #define VMAP_BLOCK_SIZE (VMAP_BBMAP_BITS * PAGE_SIZE) > > > > +#define VMAP_RAM 0x1 > > +#define VMAP_BLOCK 0x2 > > +#define VMAP_FLAGS_MASK 0x3 > > + > > struct vmap_block_queue { > > spinlock_t lock; > > struct list_head free; > > @@ -1967,6 +1972,9 @@ static void *new_vmap_block(unsigned int order, gfp_t gfp_mask) > > kfree(vb); > > return ERR_CAST(va); > > } > > + spin_lock(&vmap_area_lock); > > + va->flags = VMAP_RAM|VMAP_BLOCK; > > + spin_unlock(&vmap_area_lock); > > > The per-cpu code was created as a fast per-cpu allocator because of high > vmalloc lock contention. If possible we should avoid of locking of the > vmap_area_lock. Because it has a high contention. Fair enough. I made below draft patch to address the concern. By adding argument va_flags to alloc_vmap_area(), we can pass the vm_map_ram flags into alloc_vmap_area and filled into vmap_area->flags. With this, we don't need add extra action to acquire vmap_area_root lock and do the flags setting. Is it OK to you? From 115f6080b339d0cf9dd20c5f6c0d3121f6b22274 Mon Sep 17 00:00:00 2001 From: Baoquan He <bhe@redhat.com> Date: Wed, 7 Dec 2022 11:08:14 +0800 Subject: [PATCH] mm/vmalloc: change alloc_vmap_area() to pass in va_flags With this change, we can pass and set vmap_area->flags for vm_map_ram area in alloc_vmap_area(). Then no extra action need be added to acquire vmap_area_lock when doing the vmap_area->flags setting. Signed-off-by: Baoquan He <bhe@redhat.com> --- mm/vmalloc.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index ccaa461998f3..d74eddec352f 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1586,7 +1586,9 @@ preload_this_cpu_lock(spinlock_t *lock, gfp_t gfp_mask, int node) static struct vmap_area *alloc_vmap_area(unsigned long size, unsigned long align, unsigned long vstart, unsigned long vend, - int node, gfp_t gfp_mask) + int node, gfp_t gfp_mask, + unsigned long va_flags) +) { struct vmap_area *va; unsigned long freed; @@ -1630,6 +1632,7 @@ static struct vmap_area *alloc_vmap_area(unsigned long size, va->va_start = addr; va->va_end = addr + size; va->vm = NULL; + va->flags = va_flags; spin_lock(&vmap_area_lock); insert_vmap_area(va, &vmap_area_root, &vmap_area_list); @@ -1961,7 +1964,8 @@ static void *new_vmap_block(unsigned int order, gfp_t gfp_mask) va = alloc_vmap_area(VMAP_BLOCK_SIZE, VMAP_BLOCK_SIZE, VMALLOC_START, VMALLOC_END, - node, gfp_mask); + node, gfp_mask, + VMAP_RAM|VMAP_BLOCK); if (IS_ERR(va)) { kfree(vb); return ERR_CAST(va); @@ -2258,7 +2262,8 @@ void *vm_map_ram(struct page **pages, unsigned int count, int node) } else { struct vmap_area *va; va = alloc_vmap_area(size, PAGE_SIZE, - VMALLOC_START, VMALLOC_END, node, GFP_KERNEL); + VMALLOC_START, VMALLOC_END, + node, GFP_KERNEL, VMAP_RAM|VMAP_BLOCK); if (IS_ERR(va)) return NULL; @@ -2498,7 +2503,7 @@ static struct vm_struct *__get_vm_area_node(unsigned long size, if (!(flags & VM_NO_GUARD)) size += PAGE_SIZE; - va = alloc_vmap_area(size, align, start, end, node, gfp_mask); + va = alloc_vmap_area(size, align, start, end, node, gfp_mask, 0); if (IS_ERR(va)) { kfree(area); return NULL;
On Wed, Dec 07, 2022 at 04:03:41PM +0800, Baoquan He wrote: > On 12/05/22 at 01:56pm, Uladzislau Rezki wrote: > > > Through vmalloc API, a virtual kernel area is reserved for physical > > > address mapping. And vmap_area is used to track them, while vm_struct > > > is allocated to associate with the vmap_area to store more information > > > and passed out. > > > > > > However, area reserved via vm_map_ram() is an exception. It doesn't have > > > vm_struct to associate with vmap_area. And we can't recognize the > > > vmap_area with '->vm == NULL' as a vm_map_ram() area because the normal > > > freeing path will set va->vm = NULL before unmapping, please see > > > function remove_vm_area(). > > > > > > Meanwhile, there are two types of vm_map_ram area. One is the whole > > > vmap_area being reserved and mapped at one time; the other is the > > > whole vmap_area with VMAP_BLOCK_SIZE size being reserved, while mapped > > > into split regions with smaller size several times via vb_alloc(). > > > > > > To mark the area reserved through vm_map_ram(), add flags field into > > > struct vmap_area. Bit 0 indicates whether it's a vm_map_ram area, > > > while bit 1 indicates whether it's a vmap_block type of vm_map_ram > > > area. > > > > > > This is a preparatoin for later use. > > > > > > Signed-off-by: Baoquan He <bhe@redhat.com> > > > --- > > > include/linux/vmalloc.h | 1 + > > > mm/vmalloc.c | 18 +++++++++++++++++- > > > 2 files changed, 18 insertions(+), 1 deletion(-) > > > > > > diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h > > > index 096d48aa3437..69250efa03d1 100644 > > > --- a/include/linux/vmalloc.h > > > +++ b/include/linux/vmalloc.h > > > @@ -76,6 +76,7 @@ struct vmap_area { > > > unsigned long subtree_max_size; /* in "free" tree */ > > > struct vm_struct *vm; /* in "busy" tree */ > > > }; > > > + unsigned long flags; /* mark type of vm_map_ram area */ > > > }; > > > > > > /* archs that select HAVE_ARCH_HUGE_VMAP should override one or more of these */ > > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > > > index 5d3fd3e6fe09..d6f376060d83 100644 > > > --- a/mm/vmalloc.c > > > +++ b/mm/vmalloc.c > > > @@ -1815,6 +1815,7 @@ static void free_vmap_area_noflush(struct vmap_area *va) > > > > > > spin_lock(&vmap_area_lock); > > > unlink_va(va, &vmap_area_root); > > > + va->flags = 0; > > > spin_unlock(&vmap_area_lock); > > > > > This is not a good place to set flags to zero. It looks to me like > > corner and kind of specific. > > Thanks for reviewing. > > Here, I thought to clear VMAP_RAM|VMAP_BLOCK on vmap->flags when free > the vmap_block. I didn't find a good place to do the clearing. When we > call free_vmap_block(), we either come from purge_fragmented_blocks(), > or from vb_free(). In vb_free(), it will call free_vmap_block() when > the whole vmap_block is dirty. In purge_fragmented_blocks(), it will > try to purge all vmap_block which only has dirty or free regions. > For both of above functions, they will call free_vmap_block() when > there's no being used region in the vmap_block. > > purge_fragmented_blocks() > vb_free() > -->free_vmap_block() > > So seems we don't need to clear the VMAP_RAM|VMAP_BLOCK on vmap->flags > because there's no mapping existed in the vmap_block. The consequent > free_vmap_block() will remove the relevant vmap_area from vmap_area_list > and vmap_area_root tree. > > So I plan to remove code change in this place. > > > > > > > nr_lazy = atomic_long_add_return((va->va_end - va->va_start) >> > > > @@ -1887,6 +1888,10 @@ struct vmap_area *find_vmap_area(unsigned long addr) > > > > > > #define VMAP_BLOCK_SIZE (VMAP_BBMAP_BITS * PAGE_SIZE) > > > > > > +#define VMAP_RAM 0x1 > > > +#define VMAP_BLOCK 0x2 > > > +#define VMAP_FLAGS_MASK 0x3 > > > + > > > struct vmap_block_queue { > > > spinlock_t lock; > > > struct list_head free; > > > @@ -1967,6 +1972,9 @@ static void *new_vmap_block(unsigned int order, gfp_t gfp_mask) > > > kfree(vb); > > > return ERR_CAST(va); > > > } > > > + spin_lock(&vmap_area_lock); > > > + va->flags = VMAP_RAM|VMAP_BLOCK; > > > + spin_unlock(&vmap_area_lock); > > > > > The per-cpu code was created as a fast per-cpu allocator because of high > > vmalloc lock contention. If possible we should avoid of locking of the > > vmap_area_lock. Because it has a high contention. > > Fair enough. I made below draft patch to address the concern. By > adding argument va_flags to alloc_vmap_area(), we can pass the > vm_map_ram flags into alloc_vmap_area and filled into vmap_area->flags. > With this, we don't need add extra action to acquire vmap_area_root lock > and do the flags setting. Is it OK to you? > > From 115f6080b339d0cf9dd20c5f6c0d3121f6b22274 Mon Sep 17 00:00:00 2001 > From: Baoquan He <bhe@redhat.com> > Date: Wed, 7 Dec 2022 11:08:14 +0800 > Subject: [PATCH] mm/vmalloc: change alloc_vmap_area() to pass in va_flags > > With this change, we can pass and set vmap_area->flags for vm_map_ram area > in alloc_vmap_area(). Then no extra action need be added to acquire > vmap_area_lock when doing the vmap_area->flags setting. > > Signed-off-by: Baoquan He <bhe@redhat.com> > --- > mm/vmalloc.c | 13 +++++++++---- > 1 file changed, 9 insertions(+), 4 deletions(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index ccaa461998f3..d74eddec352f 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -1586,7 +1586,9 @@ preload_this_cpu_lock(spinlock_t *lock, gfp_t gfp_mask, int node) > static struct vmap_area *alloc_vmap_area(unsigned long size, > unsigned long align, > unsigned long vstart, unsigned long vend, > - int node, gfp_t gfp_mask) > + int node, gfp_t gfp_mask, > + unsigned long va_flags) > +) > { > struct vmap_area *va; > unsigned long freed; > @@ -1630,6 +1632,7 @@ static struct vmap_area *alloc_vmap_area(unsigned long size, > va->va_start = addr; > va->va_end = addr + size; > va->vm = NULL; > + va->flags = va_flags; > > spin_lock(&vmap_area_lock); > insert_vmap_area(va, &vmap_area_root, &vmap_area_list); > @@ -1961,7 +1964,8 @@ static void *new_vmap_block(unsigned int order, gfp_t gfp_mask) > > va = alloc_vmap_area(VMAP_BLOCK_SIZE, VMAP_BLOCK_SIZE, > VMALLOC_START, VMALLOC_END, > - node, gfp_mask); > + node, gfp_mask, > + VMAP_RAM|VMAP_BLOCK); > if (IS_ERR(va)) { > kfree(vb); > return ERR_CAST(va); > @@ -2258,7 +2262,8 @@ void *vm_map_ram(struct page **pages, unsigned int count, int node) > } else { > struct vmap_area *va; > va = alloc_vmap_area(size, PAGE_SIZE, > - VMALLOC_START, VMALLOC_END, node, GFP_KERNEL); > + VMALLOC_START, VMALLOC_END, > + node, GFP_KERNEL, VMAP_RAM|VMAP_BLOCK); > if (IS_ERR(va)) > return NULL; > > @@ -2498,7 +2503,7 @@ static struct vm_struct *__get_vm_area_node(unsigned long size, > if (!(flags & VM_NO_GUARD)) > size += PAGE_SIZE; > > - va = alloc_vmap_area(size, align, start, end, node, gfp_mask); > + va = alloc_vmap_area(size, align, start, end, node, gfp_mask, 0); > if (IS_ERR(va)) { > kfree(area); > return NULL; > -- > 2.34.1 > Yes, this is better than it was before. Adding an extra parameter makes it more valid and logical. -- Uladzislau Rezki
On 12/08/22 at 08:52pm, Uladzislau Rezki wrote: > On Wed, Dec 07, 2022 at 04:03:41PM +0800, Baoquan He wrote: ...... > > > > @@ -1967,6 +1972,9 @@ static void *new_vmap_block(unsigned int order, gfp_t gfp_mask) > > > > kfree(vb); > > > > return ERR_CAST(va); > > > > } > > > > + spin_lock(&vmap_area_lock); > > > > + va->flags = VMAP_RAM|VMAP_BLOCK; > > > > + spin_unlock(&vmap_area_lock); > > > > > > > The per-cpu code was created as a fast per-cpu allocator because of high > > > vmalloc lock contention. If possible we should avoid of locking of the > > > vmap_area_lock. Because it has a high contention. > > > > Fair enough. I made below draft patch to address the concern. By > > adding argument va_flags to alloc_vmap_area(), we can pass the > > vm_map_ram flags into alloc_vmap_area and filled into vmap_area->flags. > > With this, we don't need add extra action to acquire vmap_area_root lock > > and do the flags setting. Is it OK to you? > > > > From 115f6080b339d0cf9dd20c5f6c0d3121f6b22274 Mon Sep 17 00:00:00 2001 > > From: Baoquan He <bhe@redhat.com> > > Date: Wed, 7 Dec 2022 11:08:14 +0800 > > Subject: [PATCH] mm/vmalloc: change alloc_vmap_area() to pass in va_flags > > > > With this change, we can pass and set vmap_area->flags for vm_map_ram area > > in alloc_vmap_area(). Then no extra action need be added to acquire > > vmap_area_lock when doing the vmap_area->flags setting. > > > > Signed-off-by: Baoquan He <bhe@redhat.com> > > --- > > mm/vmalloc.c | 13 +++++++++---- > > 1 file changed, 9 insertions(+), 4 deletions(-) > > > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > > index ccaa461998f3..d74eddec352f 100644 > > --- a/mm/vmalloc.c > > +++ b/mm/vmalloc.c > > @@ -1586,7 +1586,9 @@ preload_this_cpu_lock(spinlock_t *lock, gfp_t gfp_mask, int node) > > static struct vmap_area *alloc_vmap_area(unsigned long size, > > unsigned long align, > > unsigned long vstart, unsigned long vend, > > - int node, gfp_t gfp_mask) > > + int node, gfp_t gfp_mask, > > + unsigned long va_flags) > > +) > > { > > struct vmap_area *va; > > unsigned long freed; > > @@ -1630,6 +1632,7 @@ static struct vmap_area *alloc_vmap_area(unsigned long size, > > va->va_start = addr; > > va->va_end = addr + size; > > va->vm = NULL; > > + va->flags = va_flags; > > > > spin_lock(&vmap_area_lock); > > insert_vmap_area(va, &vmap_area_root, &vmap_area_list); > > @@ -1961,7 +1964,8 @@ static void *new_vmap_block(unsigned int order, gfp_t gfp_mask) > > > > va = alloc_vmap_area(VMAP_BLOCK_SIZE, VMAP_BLOCK_SIZE, > > VMALLOC_START, VMALLOC_END, > > - node, gfp_mask); > > + node, gfp_mask, > > + VMAP_RAM|VMAP_BLOCK); > > if (IS_ERR(va)) { > > kfree(vb); > > return ERR_CAST(va); > > @@ -2258,7 +2262,8 @@ void *vm_map_ram(struct page **pages, unsigned int count, int node) > > } else { > > struct vmap_area *va; > > va = alloc_vmap_area(size, PAGE_SIZE, > > - VMALLOC_START, VMALLOC_END, node, GFP_KERNEL); > > + VMALLOC_START, VMALLOC_END, > > + node, GFP_KERNEL, VMAP_RAM|VMAP_BLOCK); > > if (IS_ERR(va)) > > return NULL; > > > > @@ -2498,7 +2503,7 @@ static struct vm_struct *__get_vm_area_node(unsigned long size, > > if (!(flags & VM_NO_GUARD)) > > size += PAGE_SIZE; > > > > - va = alloc_vmap_area(size, align, start, end, node, gfp_mask); > > + va = alloc_vmap_area(size, align, start, end, node, gfp_mask, 0); > > if (IS_ERR(va)) { > > kfree(area); > > return NULL; > > -- > > 2.34.1 > > > Yes, this is better than it was before. Adding an extra parameter makes > it more valid and logical. That's great. I will add this in v2.
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h index 096d48aa3437..69250efa03d1 100644 --- a/include/linux/vmalloc.h +++ b/include/linux/vmalloc.h @@ -76,6 +76,7 @@ struct vmap_area { unsigned long subtree_max_size; /* in "free" tree */ struct vm_struct *vm; /* in "busy" tree */ }; + unsigned long flags; /* mark type of vm_map_ram area */ }; /* archs that select HAVE_ARCH_HUGE_VMAP should override one or more of these */ diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 5d3fd3e6fe09..d6f376060d83 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1815,6 +1815,7 @@ static void free_vmap_area_noflush(struct vmap_area *va) spin_lock(&vmap_area_lock); unlink_va(va, &vmap_area_root); + va->flags = 0; spin_unlock(&vmap_area_lock); nr_lazy = atomic_long_add_return((va->va_end - va->va_start) >> @@ -1887,6 +1888,10 @@ struct vmap_area *find_vmap_area(unsigned long addr) #define VMAP_BLOCK_SIZE (VMAP_BBMAP_BITS * PAGE_SIZE) +#define VMAP_RAM 0x1 +#define VMAP_BLOCK 0x2 +#define VMAP_FLAGS_MASK 0x3 + struct vmap_block_queue { spinlock_t lock; struct list_head free; @@ -1967,6 +1972,9 @@ static void *new_vmap_block(unsigned int order, gfp_t gfp_mask) kfree(vb); return ERR_CAST(va); } + spin_lock(&vmap_area_lock); + va->flags = VMAP_RAM|VMAP_BLOCK; + spin_unlock(&vmap_area_lock); vaddr = vmap_block_vaddr(va->va_start, 0); spin_lock_init(&vb->lock); @@ -2229,8 +2237,12 @@ void vm_unmap_ram(const void *mem, unsigned int count) return; } - va = find_vmap_area(addr); + spin_lock(&vmap_area_lock); + va = __find_vmap_area((unsigned long)addr, &vmap_area_root); BUG_ON(!va); + if (va) + va->flags &= ~VMAP_RAM; + spin_unlock(&vmap_area_lock); debug_check_no_locks_freed((void *)va->va_start, (va->va_end - va->va_start)); free_unmap_vmap_area(va); @@ -2269,6 +2281,10 @@ void *vm_map_ram(struct page **pages, unsigned int count, int node) if (IS_ERR(va)) return NULL; + spin_lock(&vmap_area_lock); + va->flags = VMAP_RAM; + spin_unlock(&vmap_area_lock); + addr = va->va_start; mem = (void *)addr; }
Through vmalloc API, a virtual kernel area is reserved for physical address mapping. And vmap_area is used to track them, while vm_struct is allocated to associate with the vmap_area to store more information and passed out. However, area reserved via vm_map_ram() is an exception. It doesn't have vm_struct to associate with vmap_area. And we can't recognize the vmap_area with '->vm == NULL' as a vm_map_ram() area because the normal freeing path will set va->vm = NULL before unmapping, please see function remove_vm_area(). Meanwhile, there are two types of vm_map_ram area. One is the whole vmap_area being reserved and mapped at one time; the other is the whole vmap_area with VMAP_BLOCK_SIZE size being reserved, while mapped into split regions with smaller size several times via vb_alloc(). To mark the area reserved through vm_map_ram(), add flags field into struct vmap_area. Bit 0 indicates whether it's a vm_map_ram area, while bit 1 indicates whether it's a vmap_block type of vm_map_ram area. This is a preparatoin for later use. Signed-off-by: Baoquan He <bhe@redhat.com> --- include/linux/vmalloc.h | 1 + mm/vmalloc.c | 18 +++++++++++++++++- 2 files changed, 18 insertions(+), 1 deletion(-)