From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Subject: 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@xxxxxxxxxxxxxxxxxxxx: neaten] Reported-by: ji_ang <ji_ang@xxxxxxx> Cc: Anton Vorontsov <anton.vorontsov@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/vmpressure.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff -puN mm/vmpressure.c~mm-vmpressurec-fix-race-in-vmpressure_work_fn mm/vmpressure.c --- a/mm/vmpressure.c~mm-vmpressurec-fix-race-in-vmpressure_work_fn +++ a/mm/vmpressure.c @@ -165,6 +165,7 @@ static void vmpressure_work_fn(struct wo 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 wo * 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; _ -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html