From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id 89CA46B01EE for ; Tue, 30 Mar 2010 16:29:38 -0400 (EDT) Received: from wpaz9.hot.corp.google.com (wpaz9.hot.corp.google.com [172.24.198.73]) by smtp-out.google.com with ESMTP id o2UKTYVQ007619 for ; Tue, 30 Mar 2010 22:29:34 +0200 Received: from pwi5 (pwi5.prod.google.com [10.241.219.5]) by wpaz9.hot.corp.google.com with ESMTP id o2UKTWOr002830 for ; Tue, 30 Mar 2010 13:29:32 -0700 Received: by pwi5 with SMTP id 5so8132142pwi.19 for ; Tue, 30 Mar 2010 13:29:32 -0700 (PDT) Date: Tue, 30 Mar 2010 13:29:29 -0700 (PDT) From: David Rientjes Subject: Re: [PATCH] oom killer: break from infinite loop In-Reply-To: <20100330142923.GA10099@desktop> 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> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: anfei , KAMEZAWA Hiroyuki Cc: 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 Tue, 30 Mar 2010, anfei wrote: > > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > > > index afeab2a..9aae208 100644 > > > --- a/mm/oom_kill.c > > > +++ b/mm/oom_kill.c > > > @@ -588,12 +588,8 @@ retry: > > > if (PTR_ERR(p) == -1UL) > > > return; > > > > > > - /* Found nothing?!?! Either we hang forever, or we panic. */ > > > - if (!p) { > > > - read_unlock(&tasklist_lock); > > > - dump_header(NULL, gfp_mask, order, NULL); > > > - panic("Out of memory and no killable processes...\n"); > > > - } > > > + if (!p) > > > + p = current; > > > > > > if (oom_kill_process(p, gfp_mask, order, points, NULL, > > > "Out of memory")) > > > > The reason p wasn't selected is because it fails to meet the criteria for > > candidacy in select_bad_process(), not necessarily because of a race with > > the !p->mm check that the -mm patch cited above fixes. It's quite > > possible that current has an oom_adj value of OOM_DISABLE, for example, > > where this would be wrong. > > I see. And what about changing mem_cgroup_out_of_memory() too? > The memory controller is different because it must kill a task even if another task is exiting since the imposed limit has been reached. > 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? -- 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