Commit 601c3c29 authored by Suren Baghdasaryan's avatar Suren Baghdasaryan Committed by Andrew Morton
Browse files

mm: introduce vm_flags_reset_once to replace WRITE_ONCE vm_flags updates 

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: default avatarSuren Baghdasaryan <surenb@google.com>
Reported-by: default avatarHyeonggon Yoo <42.hyeyoo@gmail.com>
Reviewed-by: default avatarHyeonggon Yoo <42.hyeyoo@gmail.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 7e4a32c0

include/linux/mm.h

+7 −0
Original line number Diff line number Diff line
@@ -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)

{

mm/mlock.c

+2 −2
Original line number Diff line number Diff line
@@ -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);

	}

}