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UPSTREAM: mm: introduce vm_flags_reset_once to replace WRITE_ONCE vm_flags updates

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Provide vm_flags_reset_once() and replace the vm_flags updates which used
WRITE_ONCE() to prevent compiler optimizations.

Link: https://lkml.kernel.org/r/20230201000116.1333160-1-surenb@google.com
Fixes: 0cce31a0aa0e ("mm: replace vma->vm_flags direct modifications with modifier calls")
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reported-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

(cherry picked from commit 601c3c29db)

Bug: 161210518
Change-Id: Ied961a1bfbdc25b79268ba04515960c664052d61
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
This commit is contained in:
Suren Baghdasaryan
2023-01-31 16:01:16 -08:00
committed by Carlos Llamas
parent 75977e5919
commit ef8351241d
2 changed files with 9 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

7
include/linux/mm.h
View File

@@ -649,6 +649,13 @@ static inline void vm_flags_reset(struct vm_area_struct *vma,
vm_flags_init(vma, flags); vm_flags_init(vma, flags);
} }
static inline void vm_flags_reset_once(struct vm_area_struct *vma,
vm_flags_t flags)
{
mmap_assert_write_locked(vma->vm_mm);
WRITE_ONCE(ACCESS_PRIVATE(vma, __vm_flags), flags);
}
static inline void vm_flags_set(struct vm_area_struct *vma, static inline void vm_flags_set(struct vm_area_struct *vma,
vm_flags_t flags) vm_flags_t flags)
{ {

4
mm/mlock.c
View File

@@ -380,7 +380,7 @@ static void mlock_vma_pages_range(struct vm_area_struct *vma,
*/ */
if (newflags & VM_LOCKED) if (newflags & VM_LOCKED)
newflags |= VM_IO; newflags |= VM_IO;
vm_flags_reset(vma, newflags); vm_flags_reset_once(vma, newflags);
lru_add_drain(); lru_add_drain();
walk_page_range(vma->vm_mm, start, end, &mlock_walk_ops, NULL); walk_page_range(vma->vm_mm, start, end, &mlock_walk_ops, NULL);
@@ -388,7 +388,7 @@ static void mlock_vma_pages_range(struct vm_area_struct *vma,
if (newflags & VM_IO) { if (newflags & VM_IO) {
newflags &= ~VM_IO; newflags &= ~VM_IO;
vm_flags_reset(vma, newflags); vm_flags_reset_once(vma, newflags);
} }
} }