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| author | David Rientjes <rientjes@google.com> | 2014-08-06 16:07:31 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-08-06 18:01:21 -0700 |
| commit | 9ef0a0ffa28edbf5c7cfa6be73b4ecb9896a3875 (patch) | |
| tree | 6c0d71402e6c354b97eb04f4f62f00cee138ccb6 | |
| parent | 14a4e2141e24304fff2c697be6382ffb83888185 (diff) | |
| download | op-kernel-dev-9ef0a0ffa28edbf5c7cfa6be73b4ecb9896a3875.zip op-kernel-dev-9ef0a0ffa28edbf5c7cfa6be73b4ecb9896a3875.tar.gz | |
mm, writeback: prevent race when calculating dirty limits
Setting vm_dirty_bytes and dirty_background_bytes is not protected by
any serialization.
Therefore, it's possible for either variable to change value after the
test in global_dirty_limits() to determine whether available_memory
needs to be initialized or not.
Always ensure that available_memory is properly initialized.
Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/page-writeback.c | 5 |
1 files changed, 1 insertions, 4 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c index e0c94301..91d73ef 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -261,14 +261,11 @@ static unsigned long global_dirtyable_memory(void) */ void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty) { + const unsigned long available_memory = global_dirtyable_memory(); unsigned long background; unsigned long dirty; - unsigned long uninitialized_var(available_memory); struct task_struct *tsk; - if (!vm_dirty_bytes || !dirty_background_bytes) - available_memory = global_dirtyable_memory(); - if (vm_dirty_bytes) dirty = DIV_ROUND_UP(vm_dirty_bytes, PAGE_SIZE); else |
