From: Vlastimil Babka <vbabka@suse.cz>
To: Mel Gorman <mgorman@techsingularity.net>,
Ganapatrao Kulkarni <gpkulkarni@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Vlastimil Babka <vbabka@suse.cz>
Subject: [RFC 1/4] mm, page_alloc: fix check for NULL preferred_zone
Date: Tue, 17 Jan 2017 23:16:07 +0100 [thread overview]
Message-ID: <20170117221610.22505-2-vbabka@suse.cz> (raw)
In-Reply-To: <20170117221610.22505-1-vbabka@suse.cz>
Since commit c33d6c06f60f ("mm, page_alloc: avoid looking up the first zone in
a zonelist twice") we have a wrong check for NULL preferred_zone, which can
theoretically happen due to concurrent cpuset modification. We check the
zoneref pointer which is never NULL and we should check the zone pointer.
Fixes: c33d6c06f60f ("mm, page_alloc: avoid looking up the first zone in a zonelist twice")
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
mm/page_alloc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 34ada718ef47..593a11d8bc6b 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3763,7 +3763,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
*/
ac.preferred_zoneref = first_zones_zonelist(ac.zonelist,
ac.high_zoneidx, ac.nodemask);
- if (!ac.preferred_zoneref) {
+ if (!ac.preferred_zoneref->zone) {
page = NULL;
goto no_zone;
}
--
2.11.0
--
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next prev parent reply other threads:[~2017-01-17 22:16 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-17 22:16 [RFC 0/4] fix premature OOM due to cpuset races Vlastimil Babka
2017-01-17 22:16 ` Vlastimil Babka [this message]
2017-01-18 9:31 ` [RFC 1/4] mm, page_alloc: fix check for NULL preferred_zone Michal Hocko
2017-01-18 9:45 ` Vlastimil Babka
2017-01-18 9:53 ` Michal Hocko
2017-01-18 9:45 ` Mel Gorman
2017-01-17 22:16 ` [RFC 2/4] mm, page_alloc: fix fast-path race with cpuset update or removal Vlastimil Babka
2017-01-18 9:34 ` Michal Hocko
2017-01-18 9:46 ` Mel Gorman
2017-01-17 22:16 ` [RFC 3/4] mm, page_alloc: move cpuset seqcount checking to slowpath Vlastimil Babka
2017-01-18 7:22 ` Hillf Danton
2017-01-18 9:26 ` Vlastimil Babka
2017-01-18 9:40 ` Michal Hocko
2017-01-18 9:48 ` Vlastimil Babka
2017-01-18 9:55 ` Michal Hocko
2017-01-18 10:03 ` Mel Gorman
2017-01-17 22:16 ` [RFC 4/4] mm, page_alloc: fix premature OOM when racing with cpuset mems update Vlastimil Babka
2017-01-18 7:12 ` Hillf Danton
2017-01-18 9:32 ` Vlastimil Babka
2017-01-18 10:08 ` Mel Gorman
2017-01-18 9:19 ` [RFC 0/4] fix premature OOM due to cpuset races Michal Hocko
2017-01-18 16:20 ` [RFC 5/4] mm, page_alloc: fix premature OOM due to vma mempolicy update Vlastimil Babka
2017-01-18 16:23 ` Vlastimil Babka
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