From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with ESMTP id 7AF006B01F0 for ; Wed, 31 Mar 2010 02:07:18 -0400 (EDT) Received: from wpaz13.hot.corp.google.com (wpaz13.hot.corp.google.com [172.24.198.77]) by smtp-out.google.com with ESMTP id o2V67D3d000806 for ; Tue, 30 Mar 2010 23:07:13 -0700 Received: from pzk1 (pzk1.prod.google.com [10.243.19.129]) by wpaz13.hot.corp.google.com with ESMTP id o2V67B8w019880 for ; Tue, 30 Mar 2010 23:07:12 -0700 Received: by pzk1 with SMTP id 1so600349pzk.23 for ; Tue, 30 Mar 2010 23:07:11 -0700 (PDT) Date: Tue, 30 Mar 2010 23:07:08 -0700 (PDT) From: David Rientjes Subject: Re: [PATCH] oom killer: break from infinite loop In-Reply-To: <20100331095714.9137caab.kamezawa.hiroyu@jp.fujitsu.com> Message-ID: References: <1269447905-5939-1-git-send-email-anfei.zhou@gmail.com> <20100326150805.f5853d1c.akpm@linux-foundation.org> <20100326223356.GA20833@redhat.com> <20100328145528.GA14622@desktop> <20100328162821.GA16765@redhat.com> <20100329140633.GA26464@desktop> <20100330142923.GA10099@desktop> <20100331095714.9137caab.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: anfei , Oleg Nesterov , Andrew Morton , KOSAKI Motohiro , nishimura@mxp.nes.nec.co.jp, Mel Gorman , linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: 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? --- diff --git a/mm/oom_kill.c b/mm/oom_kill.c --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -500,12 +500,9 @@ void mem_cgroup_out_of_memory(struct mem_cgroup *mem, gfp_t gfp_mask) read_lock(&tasklist_lock); retry: p = select_bad_process(&points, limit, mem, CONSTRAINT_NONE, NULL); - if (PTR_ERR(p) == -1UL) + if (!p || PTR_ERR(p) == -1UL) goto out; - if (!p) - p = current; - if (oom_kill_process(p, gfp_mask, 0, points, limit, mem, "Memory cgroup out of memory")) goto retry; -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org