memcg: fix oom killing a child process in an other cgroup

Presently the oom-killer is memcg aware and it finds the worst process
from processes under memcg(s) in oom.  Then, it kills victim's child
first.

It may kill a child in another cgroup and may not be any help for
recovery.  And it will break the assumption users have.

This patch fixes it.

Signed-off-by: KAMEZAWA Hiroyuki <[email protected]>
Reviewed-by: Minchan Kim <[email protected]>
Cc: Balbir Singh <[email protected]>
Reviewed-by: Daisuke Nishimura <[email protected]>
Acked-by: David Rientjes <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index f52481b1c1e5442c9a5b16b06b22221b75b9bb7c..237050478f28f46fc59c5c9984337f1c3d60de08 100644 (file)
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -459,6 +459,8 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
        list_for_each_entry(c, &p->children, sibling) {
                if (c->mm == p->mm)
                        continue;
+               if (mem && !task_in_mem_cgroup(c, mem))
+                       continue;
                if (!oom_kill_task(c))
                        return 0;
        }