From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752417AbdHHXGn (ORCPT ); Tue, 8 Aug 2017 19:06:43 -0400 Received: from mail-pf0-f180.google.com ([209.85.192.180]:33206 "EHLO mail-pf0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752154AbdHHXGk (ORCPT ); Tue, 8 Aug 2017 19:06:40 -0400 Date: Tue, 8 Aug 2017 16:06:38 -0700 (PDT) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Roman Gushchin cc: Michal Hocko , linux-mm@kvack.org, Vladimir Davydov , Johannes Weiner , Tetsuo Handa , Tejun Heo , kernel-team@fb.com, cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [v4 2/4] mm, oom: cgroup-aware OOM killer In-Reply-To: <20170801152548.GA29502@castle.dhcp.TheFacebook.com> Message-ID: References: <20170726132718.14806-1-guro@fb.com> <20170726132718.14806-3-guro@fb.com> <20170801145435.GN15774@dhcp22.suse.cz> <20170801152548.GA29502@castle.dhcp.TheFacebook.com> User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) 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 On Tue, 1 Aug 2017, Roman Gushchin wrote: > > To the rest of the patch. I have to say I do not quite like how it is > > implemented. I was hoping for something much simpler which would hook > > into oom_evaluate_task. If a task belongs to a memcg with kill-all flag > > then we would update the cumulative memcg badness (more specifically the > > badness of the topmost parent with kill-all flag). Memcg will then > > compete with existing self contained tasks (oom_badness will have to > > tell whether points belong to a task or a memcg to allow the caller to > > deal with it). But it shouldn't be much more complex than that. > > I'm not sure, it will be any simpler. Basically I'm doing the same: > the difference is that you want to iterate over tasks and for each > task traverse the memcg tree, update per-cgroup oom score and find > the corresponding memcg(s) with the kill-all flag. I'm doing the opposite: > traverse the cgroup tree, and for each leaf cgroup iterate over processes. > > Also, please note, that even without the kill-all flag the decision is made > on per-cgroup level (except tasks in the root cgroup). > I think your implementation is preferred and is actually quite simple to follow, and I would encourage you to follow through with it. It has a similar implementation to what we have done for years to kill a process from a leaf memcg. I did notice that oom_kill_memcg_victim() calls directly into __oom_kill_process(), however, so we lack the traditional oom killer output that shows memcg usage and potential tasklist. I think we should still be dumping this information to the kernel log so that we can see a breakdown of charged memory.