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

commit 5a2d41961dd6815b874b5c0afec0ac96cd90eea4 upstream.

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 <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 9092b43f07fa01cda075b005fb66cd482eb90ecf..83cd9bb55092afd3bd18bdc2e1cce7888aa8c7a2 100644 (file)
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -426,6 +426,8 @@ 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;
        }