From: Suren Baghdasaryan <surenb@google•com>
To: akpm@linux-foundation•org
Cc: michel@lespinasse•org, joelaf@google•com, songliubraving@fb•com,
mhocko@suse•com, leewalsh@google•com, david@redhat•com,
peterz@infradead•org, bigeasy@linutronix•de, peterx@redhat•com,
dhowells@redhat•com, linux-mm@kvack•org, edumazet@google•com,
jglisse@google•com, punit.agrawal@bytedance•com,
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Subject: [PATCH 1/1] mm: introduce vm_flags_reset_once to replace WRITE_ONCE vm_flags updates
Date: Tue, 31 Jan 2023 16:01:16 -0800 [thread overview]
Message-ID: <20230201000116.1333160-1-surenb@google.com> (raw)
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);
}
}
--
2.39.1.456.gfc5497dd1b-goog
next reply other threads:[~2023-02-01 0:02 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-01 0:01 Suren Baghdasaryan [this message]
2023-02-01 7:43 ` [PATCH 1/1] mm: introduce vm_flags_reset_once to replace WRITE_ONCE vm_flags updates Michal Hocko
2023-02-08 1:46 ` Hyeonggon Yoo
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