The patch titled
Subject: mm/page_alloc: protect pcp->batch accesses with ACCESS_ONCE
has been added to the -mm tree. Its filename is
mm-page_alloc-protect-pcp-batch-accesses-with-access_once.patch
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------------------------------------------------------
From: Cody P Schafer <cody@xxxxxxxxxxxxxxxxxx>
Subject: 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@xxxxxxxxxxxxxxxxxx>
Cc: Gilad Ben-Yossef <gilad@xxxxxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff -puN mm/page_alloc.c~mm-page_alloc-protect-pcp-batch-accesses-with-access_once mm/page_alloc.c
--- a/mm/page_alloc.c~mm-page_alloc-protect-pcp-batch-accesses-with-access_once
+++ a/mm/page_alloc.c
@@ -1182,10 +1182,12 @@ void drain_zone_pages(struct zone *zone,
{
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 *pag
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:
_
Patches currently in -mm which might be from cody@xxxxxxxxxxxxxxxxxx are
mm-page_alloc-factor-out-setting-of-pcp-high-and-pcp-batch.patch
mm-page_alloc-prevent-concurrent-updaters-of-pcp-batch-and-high.patch
mm-page_alloc-insert-memory-barriers-to-allow-async-update-of-pcp-batch-and-high.patch
mm-page_alloc-protect-pcp-batch-accesses-with-access_once.patch
mm-page_alloc-convert-zone_pcp_update-to-rely-on-memory-barriers-instead-of-stop_machine.patch
mm-page_alloc-when-handling-percpu_pagelist_fraction-dont-unneedly-recalulate-high.patch
mm-page_alloc-factor-setup_pageset-into-pageset_init-and-pageset_set_batch.patch
mm-page_alloc-relocate-comment-to-be-directly-above-code-it-refers-to.patch
mm-page_alloc-factor-zone_pageset_init-out-of-setup_zone_pageset.patch
mm-page_alloc-in-zone_pcp_update-uze-zone_pageset_init.patch
mm-page_alloc-rename-setup_pagelist_highmark-to-match-naming-of-pageset_set_batch.patch
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