From: Michal Hocko <mhocko@suse.cz>
To: linux-mm@kvack.org
Cc: David Rientjes <rientjes@google.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Johannes Weiner <hannes@cmpxchg.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: [RFC PATCH] memcg: oom: fix totalpages calculation for swappiness==0
Date: Wed, 10 Oct 2012 16:11:42 +0200 [thread overview]
Message-ID: <20121010141142.GG23011@dhcp22.suse.cz> (raw)
Hi,
I am sending the patch below as an RFC because I am not entirely happy
about myself and maybe somebody can come up with a different approach
which would be less hackish.
As a background, I have noticed that memcg OOM killer kills a wrong
tasks while playing with memory.swappiness==0 in a small group (e.g.
50M). I have multiple anon mem eaters which fault in more than the hard
limit. OOM killer kills the last executed task:
# mem_eater spawns one process per parameter, mmaps the given size and
# faults memory in in parallel (all of them are synced to start together)
./mem_eater anon:50M anon:20M anon:20M anon:20M
10571: anon_eater for 20971520B
10570: anon_eater for 52428800B
10573: anon_eater for 20971520B
10572: anon_eater for 20971520B
10573: done with status 9
10571: done with status 0
10572: done with status 9
10570: done with status 9
[ pid ] uid tgid total_vm rss nr_ptes swapents oom_score_adj name
[ 5706] 0 5706 4955 556 13 0 0 bash
[10569] 0 10569 1015 134 6 0 0 mem_eater
[10570] 0 10570 13815 4118 15 0 0 mem_eater
[10571] 0 10571 6135 5140 16 0 0 mem_eater
[10572] 0 10572 6135 22 7 0 0 mem_eater
[10573] 0 10573 6135 3541 14 0 0 mem_eater
Memory cgroup out of memory: Kill process 10573 (mem_eater) score 0 or sacrifice child
Killed process 10573 (mem_eater) total-vm:24540kB, anon-rss:14028kB, file-rss:136kB
[...]
[ pid ] uid tgid total_vm rss nr_ptes swapents oom_score_adj name
[ 5706] 0 5706 4955 556 13 0 0 bash
[10569] 0 10569 1015 134 6 0 0 mem_eater
[10570] 0 10570 13815 10267 27 0 0 mem_eater
[10572] 0 10572 6135 2519 12 0 0 mem_eater
Memory cgroup out of memory: Kill process 10572 (mem_eater) score 0 or sacrifice child
Killed process 10572 (mem_eater) total-vm:24540kB, anon-rss:9940kB, file-rss:136kB
[...]
[ pid ] uid tgid total_vm rss nr_ptes swapents oom_score_adj name
[ 5706] 0 5706 4955 556 13 0 0 bash
[10569] 0 10569 1015 134 6 0 0 mem_eater
[10570] 0 10570 13815 12773 31 0 0 mem_eater
Memory cgroup out of memory: Kill process 10570 (mem_eater) score 2 or sacrifice child
Killed process 10570 (mem_eater) total-vm:55260kB, anon-rss:50956kB, file-rss:136kB
As you can see 50M (pid:10570) is killed as the last one while 20M ones
are killed first. See the patch for more details about the problem.
As I state in the changelog the very same issue is present in the global
oom killer as well but it is much less probable as the amount of swap is
usualy much smaller than the available RAM and I think it is not worth
considering.
---
next reply other threads:[~2012-10-10 14:11 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-10 14:11 Michal Hocko [this message]
2012-10-10 20:50 ` David Rientjes
2012-10-11 8:50 ` Michal Hocko
2012-10-11 8:57 ` [PATCH] memcg: oom: fix totalpages calculation for memory.swappiness==0 Michal Hocko
2012-10-11 9:13 ` Michal Hocko
2012-10-11 12:20 ` Johannes Weiner
2012-10-12 13:01 ` Michal Hocko
2012-10-11 22:36 ` KOSAKI Motohiro
2012-10-12 13:01 ` Michal Hocko
2012-10-15 22:04 ` [PATCH v2] " Michal Hocko
2012-10-15 22:07 ` [PATCH] doc: describe memcg swappiness more precisely memory.swappiness==0 Michal Hocko
2012-10-16 0:51 ` Kamezawa Hiroyuki
2012-10-16 0:54 ` David Rientjes
2012-11-07 22:10 ` [PATCH v2] memcg: oom: fix totalpages calculation for memory.swappiness==0 Andrew Morton
2012-11-07 22:46 ` Michal Hocko
2012-11-07 22:53 ` Andrew Morton
2012-11-08 8:35 ` Michal Hocko
2012-10-15 9:11 ` [RFC PATCH] memcg: oom: fix totalpages calculation for swappiness==0 Kamezawa Hiroyuki
2012-10-15 9:49 ` Michal Hocko
2012-10-15 14:25 ` KOSAKI Motohiro
2012-10-15 14:47 ` Michal Hocko
2012-10-15 22:33 ` KOSAKI Motohiro
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