Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756713Ab1CNBDt (ORCPT ); Sun, 13 Mar 2011 21:03:49 -0400 Received: from mail-iw0-f174.google.com ([209.85.214.174]:36525 "EHLO mail-iw0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756669Ab1CNBDr convert rfc822-to-8bit (ORCPT ); Sun, 13 Mar 2011 21:03:47 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=DickoEzLjCpaFrTaDMIoC8489esJRXB95H/C+QlUuYbTiLgivan4Ut7/jhiWod51lm YD4FY5toyvsgUfUxK3zj/6WX5Eze/so8rqAqr/rKJvJ1RAe9uWSYdEAzrMxCUqzrWhHp Bt05St6e9pJEcrB5ATOjI59o8IYaPCOOAGPjo= MIME-Version: 1.0 In-Reply-To: <4D79BC60.1040106@gmail.com> References: <1299325456-2687-1-git-send-email-avagin@openvz.org> <20110305152056.GA1918@barrios-desktop> <4D72580D.4000208@gmail.com> <20110305155316.GB1918@barrios-desktop> <4D7267B6.6020406@gmail.com> <20110305170759.GC1918@barrios-desktop> <20110307135831.9e0d7eaa.akpm@linux-foundation.org> <20110309143704.194e8ee1.kamezawa.hiroyu@jp.fujitsu.com> <20110311085833.874c6c0e.kamezawa.hiroyu@jp.fujitsu.com> <4D79BC60.1040106@gmail.com> Date: Mon, 14 Mar 2011 10:03:47 +0900 Message-ID: Subject: Re: [PATCH] mm: check zone->all_unreclaimable in all_unreclaimable() From: Minchan Kim To: avagin@gmail.com Cc: KAMEZAWA Hiroyuki , Andrew Morton , Andrey Vagin , Mel Gorman , KOSAKI Motohiro , linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3001 Lines: 75 On Fri, Mar 11, 2011 at 3:08 PM, avagin@gmail.com wrote: > On 03/11/2011 03:18 AM, Minchan Kim wrote: >> >> On Fri, Mar 11, 2011 at 8:58 AM, KAMEZAWA Hiroyuki >>  wrote: >>> >>> On Thu, 10 Mar 2011 15:58:29 +0900 >>> Minchan Kim  wrote: >>> >>>> Hi Kame, >>>> >>>> Sorry for late response. >>>> I had a time to test this issue shortly because these day I am very >>>> busy. >>>> This issue was interesting to me. >>>> So I hope taking a time for enough testing when I have a time. >>>> I should find out root cause of livelock. >>>> >>> >>> Thanks. I and Kosaki-san reproduced the bug with swapless system. >>> Now, Kosaki-san is digging and found some issue with scheduler boost at >>> OOM >>> and lack of enough "wait" in vmscan.c. >>> >>> I myself made patch like attached one. This works well for returning TRUE >>> at >>> all_unreclaimable() but livelock(deadlock?) still happens. >> >> I saw the deadlock. >> It seems to happen by following code by my quick debug but not sure. I >> need to investigate further but don't have a time now. :( >> >> >>                  * Note: this may have a chance of deadlock if it gets >>                  * blocked waiting for another task which itself is >> waiting >>                  * for memory. Is there a better alternative? >>                  */ >>                 if (test_tsk_thread_flag(p, TIF_MEMDIE)) >>                         return ERR_PTR(-1UL); >> It would be wait to die the task forever without another victim selection. >> If it's right, It's a known BUG and we have no choice until now. Hmm. > > > I fixed this bug too and sent patch "mm: skip zombie in OOM-killer". > > http://groups.google.com/group/linux.kernel/browse_thread/thread/b9c6ddf34d1671ab/2941e1877ca4f626?lnk=raot&pli=1 > > -               if (test_tsk_thread_flag(p, TIF_MEMDIE)) > +               if (test_tsk_thread_flag(p, TIF_MEMDIE) && p->mm) >                        return ERR_PTR(-1UL); > > It is not committed yet, because Devid Rientjes and company think what to do > with "[patch] oom: prevent unnecessary oom kills or kernel panics.". Thanks, Andrey. The patch "mm: skip zombie in OOM-killer" solves my livelock issue but I didn't look effectiveness of "mm: check zone->all_unreclaimable in all_unreclaimable". I have to look further. But your patch "mm: skip zombie in OOM-killer" is very controversial because It breaks multi-thread case. Since find_lock_task_mm is introduced, we have considered mt cases but I think it doesn't cover completely all cases like discussing TIF_MEMDIE now. I will watch the discussion. -- Kind regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/