From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Hocko Subject: Re: [PATCH v2] mm: fix oom_kill event handling Date: Thu, 10 May 2018 15:07:59 +0200 Message-ID: <20180510130759.GG5325@dhcp22.suse.cz> References: <20180508124637.29984-1-guro@fb.com> <20180510114147.GB5325@dhcp22.suse.cz> <20180510121251.GA6762@castle.DHCP.thefacebook.com> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <20180510121251.GA6762@castle.DHCP.thefacebook.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Roman Gushchin Cc: kernel-team@fb.com, Johannes Weiner , Vladimir Davydov , Andrew Morton , Konstantin Khlebnikov , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org On Thu 10-05-18 13:12:56, Roman Gushchin wrote: > On Thu, May 10, 2018 at 01:41:47PM +0200, Michal Hocko wrote: > > On Tue 08-05-18 13:46:37, Roman Gushchin wrote: > > > Commit e27be240df53 ("mm: memcg: make sure memory.events is > > > uptodate when waking pollers") converted most of memcg event > > > counters to per-memcg atomics, which made them less confusing > > > for a user. The "oom_kill" counter remained untouched, so now > > > it behaves differently than other counters (including "oom"). > > > This adds nothing but confusion. > > > > > > Let's fix this by adding the MEMCG_OOM_KILL event, and follow > > > the MEMCG_OOM approach. This also removes a hack from > > > count_memcg_event_mm(), introduced earlier specially for the > > > OOM_KILL counter. > > > > I agree that the current OOM_KILL is confusing. But do we really need > > another memcg_memory_event_mm helper used for only one counter rather > > than reuse memcg_memory_event. __oom_kill_process doesn't have the memcg > > but nothing should really prevent us from adding the context > > (oom_control) there, no? > > Not sure, that I follow. oom_control has memcg pointer, > but it's a pointer to a cgroup, where OOM happened. > In particular, it's NULL for a system-wide OOM. > > And we do send the OOM_KILL event to the cgroup, > which actually contains the process. You are right! For some reason I thought we do count events on the hierarchy which is under OOM. I was wrong. Acked-by: Michal Hocko -- Michal Hocko SUSE Labs