From: Balbir Singh <balbir@linux.vnet.ibm.com>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>,
anfei <anfei.zhou@gmail.com>, Oleg Nesterov <oleg@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
nishimura@mxp.nes.nec.co.jp, Mel Gorman <mel@csn.ul.ie>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] oom killer: break from infinite loop
Date: Wed, 31 Mar 2010 12:00:07 +0530 [thread overview]
Message-ID: <20100331063007.GN3308@balbir.in.ibm.com> (raw)
In-Reply-To: <20100331151356.673c16c0.kamezawa.hiroyu@jp.fujitsu.com>
* KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> [2010-03-31 15:13:56]:
> On Tue, 30 Mar 2010 23:07:08 -0700 (PDT)
> David Rientjes <rientjes@google.com> wrote:
>
> > On Wed, 31 Mar 2010, KAMEZAWA Hiroyuki wrote:
> >
> > > > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> > > > > index 0cb1ca4..9e89a29 100644
> > > > > --- a/mm/oom_kill.c
> > > > > +++ b/mm/oom_kill.c
> > > > > @@ -510,8 +510,10 @@ retry:
> > > > > if (PTR_ERR(p) == -1UL)
> > > > > goto out;
> > > > >
> > > > > - if (!p)
> > > > > - p = current;
> > > > > + if (!p) {
> > > > > + read_unlock(&tasklist_lock);
> > > > > + panic("Out of memory and no killable processes...\n");
> > > > > + }
> > > > >
> > > > > if (oom_kill_process(p, gfp_mask, 0, points, limit, mem,
> > > > > "Memory cgroup out of memory"))
> > > > >
> > > >
> > > > This actually does appear to be necessary but for a different reason: if
> > > > current is unkillable because it has OOM_DISABLE, for example, then
> > > > oom_kill_process() will repeatedly fail and mem_cgroup_out_of_memory()
> > > > will infinitely loop.
> > > >
> > > > Kame-san?
> > > >
> > >
> > > When a memcg goes into OOM and it only has unkillable processes (OOM_DISABLE),
> > > we can do nothing. (we can't panic because container's death != system death.)
> > >
> > > Because memcg itself has mutex+waitqueue for mutual execusion of OOM killer,
> > > I think infinite-loop will not be critical probelm for the whole system.
> > >
> > > And, now, memcg has oom-kill-disable + oom-kill-notifier features.
> > > So, If a memcg goes into OOM and there is no killable process, but oom-kill is
> > > not disabled by memcg.....it means system admin's mis-configuraton.
> > >
> > > He can stop inifite loop by hand, anyway.
> > > # echo 1 > ..../group_A/memory.oom_control
> > >
> >
> > Then we should be able to do this since current is by definition
> > unkillable since it was not found in select_bad_process(), right?
>
> To me, this patch is acceptable and seems reasnoable.
>
> But I didn't joined to memcg development when this check was added
> and don't know why kill current..
>
The reason for adding current was that we did not want to loop
forever, since it stops forward progress - no error/no forward
progress. It made sense to oom kill the current process, so that the
cgroup admin could look at what went wrong.
> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=c7ba5c9e8176704bfac0729875fa62798037584d
>
> Addinc Balbir to CC. Maybe situation is changed now.
> Because we can stop inifinite loop (by hand) and there is no rushing oom-kill
> callers, this change is acceptable.
>
By hand is not always possible if we have a large number of cgroups
(I've seen a setup with 2000 cgroups on libcgroup ML). 2000 cgroups *
number of processes make the situation complex. I think using OOM
notifier is now another way of handling such a situation.
--
Three Cheers,
Balbir
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next prev parent reply other threads:[~2010-03-31 6:30 UTC|newest]
Thread overview: 115+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-24 16:25 [PATCH] oom killer: break from infinite loop Anfei Zhou
2010-03-25 2:51 ` KOSAKI Motohiro
2010-03-26 22:08 ` Andrew Morton
2010-03-26 22:33 ` Oleg Nesterov
2010-03-28 14:55 ` anfei
2010-03-28 16:28 ` Oleg Nesterov
2010-03-28 21:21 ` David Rientjes
2010-03-29 11:21 ` Oleg Nesterov
2010-03-29 20:49 ` [patch] oom: give current access to memory reserves if it has been killed David Rientjes
2010-03-30 15:46 ` Oleg Nesterov
2010-03-30 20:26 ` David Rientjes
2010-03-31 17:58 ` Oleg Nesterov
2010-03-31 20:47 ` Oleg Nesterov
2010-04-01 8:35 ` David Rientjes
2010-04-01 8:57 ` [patch -mm] oom: hold tasklist_lock when dumping tasks David Rientjes
2010-04-01 14:27 ` Oleg Nesterov
2010-04-01 19:16 ` David Rientjes
2010-04-01 13:59 ` [patch] oom: give current access to memory reserves if it has been killed Oleg Nesterov
2010-04-01 19:12 ` David Rientjes
2010-04-02 11:14 ` Oleg Nesterov
2010-04-02 18:30 ` [PATCH -mm 0/4] oom: linux has threads Oleg Nesterov
2010-04-02 18:31 ` [PATCH -mm 1/4] oom: select_bad_process: check PF_KTHREAD instead of !mm to skip kthreads Oleg Nesterov
2010-04-02 19:05 ` David Rientjes
2010-04-02 18:32 ` [PATCH -mm 2/4] oom: select_bad_process: PF_EXITING check should take ->mm into account Oleg Nesterov
2010-04-06 11:42 ` anfei
2010-04-06 12:18 ` Oleg Nesterov
2010-04-06 13:05 ` anfei
2010-04-06 13:38 ` Oleg Nesterov
2010-04-02 18:32 ` [PATCH -mm 3/4] oom: introduce find_lock_task_mm() to fix !mm false positives Oleg Nesterov
2010-04-02 18:33 ` [PATCH -mm 4/4] oom: oom_forkbomb_penalty: move thread_group_cputime() out of task_lock() Oleg Nesterov
2010-04-02 19:04 ` David Rientjes
2010-04-05 14:23 ` [PATCH -mm] oom: select_bad_process: never choose tasks with badness == 0 Oleg Nesterov
2010-04-02 19:02 ` [patch] oom: give current access to memory reserves if it has been killed David Rientjes
2010-04-02 19:14 ` Oleg Nesterov
2010-04-02 19:46 ` David Rientjes
2010-04-02 19:54 ` [patch -mm] oom: exclude tasks with badness score of 0 from being selected David Rientjes
2010-04-02 21:04 ` Oleg Nesterov
2010-04-02 21:22 ` [patch -mm v2] " David Rientjes
2010-04-02 20:55 ` [patch] oom: give current access to memory reserves if it has been killed Oleg Nesterov
2010-03-31 21:07 ` David Rientjes
2010-03-31 22:50 ` Oleg Nesterov
2010-03-31 23:30 ` Oleg Nesterov
2010-03-31 23:48 ` David Rientjes
2010-04-01 14:39 ` Oleg Nesterov
2010-04-01 18:58 ` David Rientjes
2010-04-01 8:25 ` David Rientjes
2010-04-01 15:26 ` Oleg Nesterov
2010-04-08 21:08 ` David Rientjes
2010-04-09 12:38 ` Oleg Nesterov
2010-03-30 16:39 ` [PATCH] oom: fix the unsafe proc_oom_score()->badness() call Oleg Nesterov
2010-03-30 17:43 ` [PATCH -mm] proc: don't take ->siglock for /proc/pid/oom_adj Oleg Nesterov
2010-03-30 20:30 ` David Rientjes
2010-03-31 9:17 ` Oleg Nesterov
2010-03-31 18:59 ` Oleg Nesterov
2010-03-31 21:14 ` David Rientjes
2010-03-31 23:00 ` Oleg Nesterov
2010-04-01 8:32 ` David Rientjes
2010-04-01 15:37 ` Oleg Nesterov
2010-04-01 19:04 ` David Rientjes
2010-03-30 20:32 ` [PATCH] oom: fix the unsafe proc_oom_score()->badness() call David Rientjes
2010-03-31 9:16 ` Oleg Nesterov
2010-03-31 20:17 ` Oleg Nesterov
2010-04-01 7:41 ` David Rientjes
2010-04-01 13:13 ` [PATCH 0/1] oom: fix the unsafe usage of badness() in proc_oom_score() Oleg Nesterov
2010-04-01 13:13 ` [PATCH 1/1] " Oleg Nesterov
2010-04-01 19:03 ` David Rientjes
2010-03-29 14:06 ` [PATCH] oom killer: break from infinite loop anfei
2010-03-29 20:01 ` David Rientjes
2010-03-30 14:29 ` anfei
2010-03-30 20:29 ` David Rientjes
2010-03-31 0:57 ` KAMEZAWA Hiroyuki
2010-03-31 6:07 ` David Rientjes
2010-03-31 6:13 ` KAMEZAWA Hiroyuki
2010-03-31 6:30 ` Balbir Singh [this message]
2010-03-31 6:31 ` KAMEZAWA Hiroyuki
2010-03-31 7:04 ` David Rientjes
2010-03-31 6:32 ` David Rientjes
2010-03-31 7:08 ` [patch -mm] memcg: make oom killer a no-op when no killable task can be found David Rientjes
2010-03-31 7:08 ` KAMEZAWA Hiroyuki
2010-03-31 8:04 ` Balbir Singh
2010-03-31 10:38 ` David Rientjes
2010-04-04 23:28 ` David Rientjes
2010-04-05 21:30 ` Andrew Morton
2010-04-05 22:40 ` David Rientjes
2010-04-05 22:49 ` Andrew Morton
2010-04-05 23:01 ` David Rientjes
2010-04-06 12:08 ` KOSAKI Motohiro
2010-04-06 21:47 ` David Rientjes
2010-04-07 0:20 ` KAMEZAWA Hiroyuki
2010-04-07 13:29 ` KOSAKI Motohiro
2010-04-08 18:05 ` David Rientjes
2010-04-21 19:17 ` Andrew Morton
2010-04-21 22:04 ` David Rientjes
2010-04-22 0:23 ` KAMEZAWA Hiroyuki
2010-04-22 8:34 ` David Rientjes
2010-04-27 22:58 ` [patch -mm] oom: reintroduce and deprecate oom_kill_allocating_task David Rientjes
2010-04-28 0:57 ` KAMEZAWA Hiroyuki
2010-04-22 7:23 ` [patch -mm] memcg: make oom killer a no-op when no killable task can be found Nick Piggin
2010-04-22 7:25 ` KAMEZAWA Hiroyuki
2010-04-22 10:09 ` Nick Piggin
2010-04-22 10:27 ` KAMEZAWA Hiroyuki
2010-04-22 21:11 ` David Rientjes
2010-04-22 10:28 ` David Rientjes
2010-04-22 15:39 ` Nick Piggin
2010-04-22 21:09 ` David Rientjes
2010-05-04 23:55 ` David Rientjes
2010-04-08 17:36 ` David Rientjes
2010-04-02 10:17 ` [PATCH] oom killer: break from infinite loop Mel Gorman
2010-04-04 23:26 ` David Rientjes
2010-04-05 10:47 ` Mel Gorman
2010-04-06 22:40 ` David Rientjes
2010-03-29 11:31 ` anfei
2010-03-29 11:46 ` Oleg Nesterov
2010-03-29 12:09 ` anfei
2010-03-28 2:46 ` David Rientjes
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