From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965307AbcBQNKi (ORCPT ); Wed, 17 Feb 2016 08:10:38 -0500 Received: from mail-wm0-f52.google.com ([74.125.82.52]:33839 "EHLO mail-wm0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964898AbcBQNKh (ORCPT ); Wed, 17 Feb 2016 08:10:37 -0500 Date: Wed, 17 Feb 2016 14:10:35 +0100 From: Michal Hocko To: Tetsuo Handa Cc: akpm@linux-foundation.org, rientjes@google.com, mgorman@suse.de, oleg@redhat.com, torvalds@linux-foundation.org, hughd@google.com, andrea@kernel.org, riel@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 4/6] mm,oom: exclude oom_task_origin processes if they are OOM-unkillable. Message-ID: <20160217131034.GH29196@dhcp22.suse.cz> References: <201602171928.GDE00540.SLJMOFFQOHtFVO@I-love.SAKURA.ne.jp> <201602171933.HFD51078.LOSFVMFQFOJHOt@I-love.SAKURA.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201602171933.HFD51078.LOSFVMFQFOJHOt@I-love.SAKURA.ne.jp> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 17-02-16 19:33:07, Tetsuo Handa wrote: > >From 4924ca3031444bfb831b2d4f004e5a613ad48d68 Mon Sep 17 00:00:00 2001 > From: Tetsuo Handa > Date: Wed, 17 Feb 2016 16:35:12 +0900 > Subject: [PATCH 4/6] mm,oom: exclude oom_task_origin processes if they are OOM-unkillable. > > oom_scan_process_thread() returns OOM_SCAN_SELECT when there is a > thread which returns oom_task_origin() == true. But it is possible > that that thread is marked as OOM-unkillable. > > This patch changes oom_scan_process_thread() not to select it > if it is marked as OOM-unkillable. oom_task_origin is only swapoff and ksm_store right now. I seriously doubt anybody sane will run them as OOM disabled (directly or indirectly). But you have a point that returing anything but OOM_SCAN_CONTINUE for OOM_SCORE_ADJ_MIN from oom_scan_process_thread sounds suboptimal. Sure such a check would be racy but do we actually care about a OOM vs. oom_score_adj_write. I am dubious to say the least. So wouldn't it make more sense to check for OOM_SCORE_ADJ_MIN at the very top of oom_scan_process_thread instead? > Signed-off-by: Tetsuo Handa > --- > mm/oom_kill.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index b0c327d..ebc6764 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -308,7 +308,8 @@ enum oom_scan_t oom_scan_process_thread(struct oom_control *oc, > * If task is allocating a lot of memory and has been marked to be > * killed first if it triggers an oom, then select it. > */ > - if (oom_task_origin(task) && !test_tsk_thread_flag(task, TIF_MEMDIE)) > + if (oom_task_origin(task) && !test_tsk_thread_flag(task, TIF_MEMDIE) && > + task->signal->oom_score_adj != OOM_SCORE_ADJ_MIN) > return OOM_SCAN_SELECT; > > return OOM_SCAN_OK; > -- > 1.8.3.1 -- Michal Hocko SUSE Labs