diff options
| author | Andrew Morton <akpm@linux-foundation.org> | 2014-12-02 15:59:28 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-12-02 17:32:07 -0800 |
| commit | 91b57191cfd152c02ded0745250167d0263084f8 (patch) | |
| tree | 677bb8c059094859904003cb7af01cbee1d9773e /mm/vmpressure.c | |
| parent | fb993fa1a2f669215fa03a09eed7848f2663e336 (diff) | |
| download | lwn-91b57191cfd152c02ded0745250167d0263084f8.tar.gz lwn-91b57191cfd152c02ded0745250167d0263084f8.zip | |
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>
Diffstat (limited to 'mm/vmpressure.c')
| -rw-r--r-- | mm/vmpressure.c | 8 |
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; |