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authorAndrew Morton <akpm@linux-foundation.org>2014-12-02 15:59:28 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-12-02 17:32:07 -0800
commit91b57191cfd152c02ded0745250167d0263084f8 (patch)
tree677bb8c059094859904003cb7af01cbee1d9773e
parentfb993fa1a2f669215fa03a09eed7848f2663e336 (diff)
downloadlinux-linaro-stable-91b57191cfd152c02ded0745250167d0263084f8.tar.gz
mm/vmpressure.c: fix race in vmpressure_work_fn()
In some android devices, there will be a "divide by zero" exception. vmpr->scanned could be zero before spin_lock(&vmpr->sr_lock). Addresses https://bugzilla.kernel.org/show_bug.cgi?id=88051 [akpm@linux-foundation.org: neaten] Reported-by: ji_ang <ji_ang@163.com> Cc: Anton Vorontsov <anton.vorontsov@linaro.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/vmpressure.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/mm/vmpressure.c b/mm/vmpressure.c
index d4042e75f7c7..c5afd573d7da 100644
--- a/mm/vmpressure.c
+++ b/mm/vmpressure.c
@@ -165,6 +165,7 @@ static void vmpressure_work_fn(struct work_struct *work)
unsigned long scanned;
unsigned long reclaimed;
+ spin_lock(&vmpr->sr_lock);
/*
* Several contexts might be calling vmpressure(), so it is
* possible that the work was rescheduled again before the old
@@ -173,11 +174,12 @@ static void vmpressure_work_fn(struct work_struct *work)
* here. No need for any locks here since we don't care if
* vmpr->reclaimed is in sync.
*/
- if (!vmpr->scanned)
+ scanned = vmpr->scanned;
+ if (!scanned) {
+ spin_unlock(&vmpr->sr_lock);
return;
+ }
- spin_lock(&vmpr->sr_lock);
- scanned = vmpr->scanned;
reclaimed = vmpr->reclaimed;
vmpr->scanned = 0;
vmpr->reclaimed = 0;