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authorCody P Schafer <cody@linux.vnet.ibm.com>2013-07-03 15:01:32 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-07-03 16:07:27 -0700
commit998d39cb236fe464af86a3492a24d2f67ee1efc2 (patch)
treec093fb89e8d4a4b62e656f5becf92876ce13f958 /mm/page_alloc.c
parent8d7a8fa97abeb4fd6b3975d32c9f859875157770 (diff)
downloadop-kernel-dev-998d39cb236fe464af86a3492a24d2f67ee1efc2.zip
op-kernel-dev-998d39cb236fe464af86a3492a24d2f67ee1efc2.tar.gz
mm/page_alloc: protect pcp->batch accesses with ACCESS_ONCE
pcp->batch could change at any point, avoid relying on it being a stable value. Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Gilad Ben-Yossef <gilad@benyossef.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page_alloc.c')
-rw-r--r--mm/page_alloc.c11
1 files changed, 7 insertions, 4 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index eaaef2a..97b8f86 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1182,10 +1182,12 @@ void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp)
{
unsigned long flags;
int to_drain;
+ unsigned long batch;
local_irq_save(flags);
- if (pcp->count >= pcp->batch)
- to_drain = pcp->batch;
+ batch = ACCESS_ONCE(pcp->batch);
+ if (pcp->count >= batch)
+ to_drain = batch;
else
to_drain = pcp->count;
if (to_drain > 0) {
@@ -1353,8 +1355,9 @@ void free_hot_cold_page(struct page *page, int cold)
list_add(&page->lru, &pcp->lists[migratetype]);
pcp->count++;
if (pcp->count >= pcp->high) {
- free_pcppages_bulk(zone, pcp->batch, pcp);
- pcp->count -= pcp->batch;
+ unsigned long batch = ACCESS_ONCE(pcp->batch);
+ free_pcppages_bulk(zone, batch, pcp);
+ pcp->count -= batch;
}
out:
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