From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751590AbdGZN4b (ORCPT ); Wed, 26 Jul 2017 09:56:31 -0400 Received: from mx2.suse.de ([195.135.220.15]:43578 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750922AbdGZN4a (ORCPT ); Wed, 26 Jul 2017 09:56:30 -0400 Date: Wed, 26 Jul 2017 15:56:22 +0200 From: Michal Hocko To: Roman Gushchin Cc: linux-mm@kvack.org, Vladimir Davydov , Johannes Weiner , Tetsuo Handa , David Rientjes , Tejun Heo , kernel-team@fb.com, cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [v4 1/4] mm, oom: refactor the TIF_MEMDIE usage Message-ID: <20170726135622.GS2981@dhcp22.suse.cz> References: <20170726132718.14806-1-guro@fb.com> <20170726132718.14806-2-guro@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170726132718.14806-2-guro@fb.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 26-07-17 14:27:15, Roman Gushchin wrote: [...] > @@ -656,13 +658,24 @@ static void mark_oom_victim(struct task_struct *tsk) > struct mm_struct *mm = tsk->mm; > > WARN_ON(oom_killer_disabled); > - /* OOM killer might race with memcg OOM */ > - if (test_and_set_tsk_thread_flag(tsk, TIF_MEMDIE)) > + > + if (!cmpxchg(&tif_memdie_owner, NULL, current)) { > + struct task_struct *t; > + > + rcu_read_lock(); > + for_each_thread(current, t) > + set_tsk_thread_flag(t, TIF_MEMDIE); > + rcu_read_unlock(); > + } I would realy much rather see we limit the amount of memory reserves oom victims can consume rather than build on top of the current hackish approach of limiting the number of tasks because the fundamental problem is still there (a heavy multithreaded process can still deplete the reserves completely). Is there really any reason to not go with the existing patch I've pointed to the last time around? You didn't seem to have any objects back then. -- Michal Hocko SUSE Labs