From: Li RongQing Date: Fri, 27 May 2016 21:27:43 +0000 (-0700) Subject: mm/memcontrol.c: fix the margin computation in mem_cgroup_margin() X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=cbedbac3e66121ddbac363776c23119f8eaeefda;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git 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 Acked-by: Vladimir Davydov Acked-by: Michal Hocko Cc: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- 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;