Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934213AbcCIWXc (ORCPT ); Wed, 9 Mar 2016 17:23:32 -0500 Received: from www262.sakura.ne.jp ([202.181.97.72]:64417 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751476AbcCIWXY (ORCPT ); Wed, 9 Mar 2016 17:23:24 -0500 To: akpm@linux-foundation.org, mhocko@kernel.org Cc: linux-mm@kvack.org, rientjes@google.com, linux-kernel@vger.kernel.org, mhocko@suse.com, hannes@cmpxchg.org Subject: Re: [PATCH 2/2] oom-clear-tif_memdie-after-oom_reaper-managed-to-unmap-the-address-space-fix From: Tetsuo Handa References: <1457442737-8915-1-git-send-email-mhocko@kernel.org> <1457442737-8915-3-git-send-email-mhocko@kernel.org> <20160309132142.80d0afbf0ae398df8e2adba8@linux-foundation.org> In-Reply-To: <20160309132142.80d0afbf0ae398df8e2adba8@linux-foundation.org> Message-Id: <201603100721.CDC86433.OMFOVOHSJFLFQt@I-love.SAKURA.ne.jp> X-Mailer: Winbiff [Version 2.51 PL2] X-Accept-Language: ja,en,zh Date: Thu, 10 Mar 2016 07:21:58 +0900 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2072 Lines: 56 Andrew Morton wrote: > I found the below patch lying around but I didn't queue it properly. > Is it legit? I think that patch wants patch description updated. Not testing pure noise, but causing possible livelock. http://lkml.kernel.org/r/20160217143917.GP29196@dhcp22.suse.cz > > > From: Johannes Weiner > Subject: oom-clear-tif_memdie-after-oom_reaper-managed-to-unmap-the-address-space-fix > > When the OOM killer scans tasks and encounters a PF_EXITING one, it > force-selects that one regardless of the score. Is there a possibility > that the task might hang after it has set PF_EXITING? In that case the > OOM killer should be able to move on to the next task. > > Frankly, I don't even know why we check for exiting tasks in the OOM > killer. We've tried direct reclaim at least 15 times by the time we > decide the system is OOM, there was plenty of time to exit and free > memory; and a task might exit voluntarily right after we issue a kill. > This is testing pure noise. > > Cc: Tetsuo Handa > Cc: Michal Hocko > Cc: Kirill A. Shutemov > Cc: Mel Gorman > Cc: David Rientjes > Cc: Oleg Nesterov > Cc: Hugh Dickins > Cc: Andrea Argangeli > Cc: Rik van Riel > Cc: Sasha Levin > Signed-off-by: Andrew Morton > --- > > mm/oom_kill.c | 3 --- > 1 file changed, 3 deletions(-) > > diff -puN mm/oom_kill.c~oom-clear-tif_memdie-after-oom_reaper-managed-to-unmap-the-address-space-fix mm/oom_kill.c > --- a/mm/oom_kill.c~oom-clear-tif_memdie-after-oom_reaper-managed-to-unmap-the-address-space-fix > +++ a/mm/oom_kill.c > @@ -292,9 +292,6 @@ enum oom_scan_t oom_scan_process_thread( > if (oom_task_origin(task)) > return OOM_SCAN_SELECT; > > - if (task_will_free_mem(task) && !is_sysrq_oom(oc)) > - return OOM_SCAN_ABORT; > - > return OOM_SCAN_OK; > } > > _ > >