Eric Lee / smarc-ti-linux-kernel

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Commit 91b57191cfd152c02ded0745250167d0263084f8

Authored by Andrew Morton
Committed by Linus Torvalds
1 parent fb993fa1a2
Exists in ti-lsk-linux-4.1.y and in 10 other branches dlt-processor-sdk-linux-03.00.00.04, processor-sdk-linux-02.00.01, smarc-ti-lsk-linux-4.1.y, smarct3x-processor-sdk-04.01.00.06, smarct3x-processor-sdk-linux-02.00.01, smarct3x-processor-sdk-linux-03.00.00.04, smarct4x-800-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-04.01.00.06, smarct4x-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-linux-03.00.00.04

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>

Showing 1 changed file with 5 additions and 3 deletions Side-by-side Diff

... ... @@ -165,6 +165,7 @@
165 165 unsigned long scanned;
166 166 unsigned long reclaimed;
167 167  
  168 + spin_lock(&vmpr->sr_lock);
168 169 /*
169 170 * Several contexts might be calling vmpressure(), so it is
170 171 * possible that the work was rescheduled again before the old
171 172  
172 173  
... ... @@ -173,11 +174,12 @@
173 174 * here. No need for any locks here since we don't care if
174 175 * vmpr->reclaimed is in sync.
175 176 */
176   - if (!vmpr->scanned)
  177 + scanned = vmpr->scanned;
  178 + if (!scanned) {
  179 + spin_unlock(&vmpr->sr_lock);
177 180 return;
  181 + }
178 182  
179   - spin_lock(&vmpr->sr_lock);
180   - scanned = vmpr->scanned;
181 183 reclaimed = vmpr->reclaimed;
182 184 vmpr->scanned = 0;
183 185 vmpr->reclaimed = 0;