| Message ID | 20230201000116.1333160-1-surenb@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [1/1] mm: introduce vm_flags_reset_once to replace WRITE_ONCE vm_flags updates | expand |
On Tue 31-01-23 16:01:16, Suren Baghdasaryan wrote: > Provide vm_flags_reset_once() and replace the vm_flags updates which used > WRITE_ONCE() to prevent compiler optimizations. > > Fixes: 0cce31a0aa0e ("mm: replace vma->vm_flags direct modifications with modifier calls") > Reported-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> > Signed-off-by: Suren Baghdasaryan <surenb@google.com> This would have been better folded into the vm_flags modification patch because it would be more obvious change. Hugh has provided a very nice comment in mlock_vma_pages_range but the git blame would be more visible when the conversion is from WRITE_ONCE. One way or the other Acked-by: Michal Hocko <mhocko@suse.com> > --- > Notes: > - The patch applies cleanly over mm-unstable > - The SHA in Fixes: line is from mm-unstable, so is... unstable > > include/linux/mm.h | 7 +++++++ > mm/mlock.c | 4 ++-- > 2 files changed, 9 insertions(+), 2 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 5bf0ad48faaa..23ce04f6e91e 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -648,6 +648,13 @@ 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) > { > diff --git a/mm/mlock.c b/mm/mlock.c > index ed49459e343e..617469fce96d 100644 > --- a/mm/mlock.c > +++ b/mm/mlock.c > @@ -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); > } > } > > -- > 2.39.1.456.gfc5497dd1b-goog
On Tue, Jan 31, 2023 at 04:01:16PM -0800, Suren Baghdasaryan wrote: > Provide vm_flags_reset_once() and replace the vm_flags updates which used > WRITE_ONCE() to prevent compiler optimizations. > > Fixes: 0cce31a0aa0e ("mm: replace vma->vm_flags direct modifications with modifier calls") > Reported-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> > Signed-off-by: Suren Baghdasaryan <surenb@google.com> > --- > Notes: > - The patch applies cleanly over mm-unstable > - The SHA in Fixes: line is from mm-unstable, so is... unstable > > include/linux/mm.h | 7 +++++++ > mm/mlock.c | 4 ++-- > 2 files changed, 9 insertions(+), 2 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 5bf0ad48faaa..23ce04f6e91e 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -648,6 +648,13 @@ 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) > { > diff --git a/mm/mlock.c b/mm/mlock.c > index ed49459e343e..617469fce96d 100644 > --- a/mm/mlock.c > +++ b/mm/mlock.c > @@ -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); > } > } Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> > > -- > 2.39.1.456.gfc5497dd1b-goog >
diff --git a/include/linux/mm.h b/include/linux/mm.h index 5bf0ad48faaa..23ce04f6e91e 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -648,6 +648,13 @@ 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) { diff --git a/mm/mlock.c b/mm/mlock.c index ed49459e343e..617469fce96d 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -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); } }
Provide vm_flags_reset_once() and replace the vm_flags updates which used WRITE_ONCE() to prevent compiler optimizations. Fixes: 0cce31a0aa0e ("mm: replace vma->vm_flags direct modifications with modifier calls") Reported-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Signed-off-by: Suren Baghdasaryan <surenb@google.com> --- Notes: - The patch applies cleanly over mm-unstable - The SHA in Fixes: line is from mm-unstable, so is... unstable include/linux/mm.h | 7 +++++++ mm/mlock.c | 4 ++-- 2 files changed, 9 insertions(+), 2 deletions(-)