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authorLi RongQing <roy.qing.li@gmail.com>2016-05-27 14:27:43 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-05-27 14:49:37 -0700
commitcbedbac3e66121ddbac363776c23119f8eaeefda (patch)
tree2705dfac84c6f79bef0415ca662eb98fe44d6a1d
parentbadbda53e505089062e194c614e6f23450bc98b2 (diff)
mm/memcontrol.c: fix the margin computation in mem_cgroup_margin()
mem_cgroup_margin() might return (memory.limit - memory_count) when the memsw.limit is in excess. This doesn't happen usually because we do not allow excess on hard limits and (memory.limit <= memsw.limit), but __GFP_NOFAIL charges can force the charge and cause the excess when no memory is really swappable (swap is full or no anonymous memory is left). [mhocko@suse.com: rewrote changelog] Link: http://lkml.kernel.org/r/20160525155122.GK20132@dhcp22.suse.cz Link: http://lkml.kernel.org/r/1464068266-27736-1-git-send-email-roy.qing.li@gmail.com Signed-off-by: Li RongQing <roy.qing.li@gmail.com> Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/memcontrol.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index f6477a9dbe7a..485c688a7fa8 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1108,6 +1108,8 @@ static unsigned long mem_cgroup_margin(struct mem_cgroup *memcg)
limit = READ_ONCE(memcg->memsw.limit);
if (count <= limit)
margin = min(margin, limit - count);
+ else
+ margin = 0;
}
return margin;