From: Li RongQing <roy.qing.li@xxxxxxxxx> Subject: 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@xxxxxxxx: rewrote changelog] Link: http://lkml.kernel.org/r/20160525155122.GK20132@xxxxxxxxxxxxxx Link: http://lkml.kernel.org/r/1464068266-27736-1-git-send-email-roy.qing.li@xxxxxxxxx Signed-off-by: Li RongQing <roy.qing.li@xxxxxxxxx> Acked-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/memcontrol.c | 2 ++ 1 file changed, 2 insertions(+) diff -puN mm/memcontrol.c~mm-memcontrol-fix-the-margin-computation-in-mem_cgroup_margin mm/memcontrol.c --- a/mm/memcontrol.c~mm-memcontrol-fix-the-margin-computation-in-mem_cgroup_margin +++ a/mm/memcontrol.c @@ -1108,6 +1108,8 @@ static unsigned long mem_cgroup_margin(s limit = READ_ONCE(memcg->memsw.limit); if (count <= limit) margin = min(margin, limit - count); + else + margin = 0; } return margin; _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
