From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752617AbcFPGbd (ORCPT ); Thu, 16 Jun 2016 02:31:33 -0400 Received: from mail-pf0-f194.google.com ([209.85.192.194]:35519 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751490AbcFPGbb (ORCPT ); Thu, 16 Jun 2016 02:31:31 -0400 Date: Thu, 16 Jun 2016 08:31:27 +0200 From: Michal Hocko To: Oleg Nesterov Cc: linux-mm@kvack.org, Tetsuo Handa , David Rientjes , Vladimir Davydov , Andrew Morton , LKML Subject: Re: [PATCH 10/10] mm, oom: hide mm which is shared with kthread or global init Message-ID: <20160616063126.GC30768@dhcp22.suse.cz> References: <1465473137-22531-1-git-send-email-mhocko@kernel.org> <1465473137-22531-11-git-send-email-mhocko@kernel.org> <20160615143701.GA7944@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160615143701.GA7944@redhat.com> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 15-06-16 16:37:01, Oleg Nesterov wrote: > Michal, > > I am going to ack the whole series, but send some nits/questions, > > On 06/09, Michal Hocko wrote: > > > > @@ -283,10 +283,22 @@ enum oom_scan_t oom_scan_process_thread(struct oom_control *oc, > > > > /* > > * This task already has access to memory reserves and is being killed. > > - * Don't allow any other task to have access to the reserves. > > + * Don't allow any other task to have access to the reserves unless > > + * the task has MMF_OOM_REAPED because chances that it would release > > + * any memory is quite low. > > */ > > - if (!is_sysrq_oom(oc) && atomic_read(&task->signal->oom_victims)) > > - return OOM_SCAN_ABORT; > > + if (!is_sysrq_oom(oc) && atomic_read(&task->signal->oom_victims)) { > > + struct task_struct *p = find_lock_task_mm(task); > > + enum oom_scan_t ret = OOM_SCAN_ABORT; > > + > > + if (p) { > > + if (test_bit(MMF_OOM_REAPED, &p->mm->flags)) > > + ret = OOM_SCAN_CONTINUE; > > + task_unlock(p); > > OK, but perhaps it would be beter to change oom_badness() to return zero if > MMF_OOM_REAPED is set? We already do that: if (adj == OOM_SCORE_ADJ_MIN || test_bit(MMF_OOM_REAPED, &p->mm->flags) || in_vfork(p)) { task_unlock(p); return 0; } It is kind of subtle that we have to check it 2 times but we would have to rework this code much more because oom_badness only can tell to ignore the task but not to abort scanning altogether currently. If we should change this I would suggest a separate patch. -- Michal Hocko SUSE Labs