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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>
This commit is contained in:
Suren Baghdasaryan 2023-01-31 16:01:16 -08:00 committed by Andrew Morton
parent 7e4a32c0e8
commit 601c3c29db
2 changed files with 9 additions and 2 deletions
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7
include/linux/mm.h
View file

@ -642,6 +642,13 @@ static inline void vm_flags_reset(struct vm_area_struct *vma,
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,
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)
newflags |= VM_IO;
vm_flags_reset(vma, newflags);
vm_flags_reset_once(vma, newflags);
lru_add_drain();
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) {
newflags &= ~VM_IO;
vm_flags_reset(vma, newflags);
vm_flags_reset_once(vma, newflags);
}
}