From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f70.google.com (mail-pg0-f70.google.com [74.125.83.70]) by kanga.kvack.org (Postfix) with ESMTP id BF7066B05FC for ; Thu, 10 May 2018 08:13:28 -0400 (EDT) Received: by mail-pg0-f70.google.com with SMTP id z16-v6so740976pgv.16 for ; Thu, 10 May 2018 05:13:28 -0700 (PDT) Received: from mx0a-00082601.pphosted.com (mx0b-00082601.pphosted.com. [67.231.153.30]) by mx.google.com with ESMTPS id 127-v6si705133pfe.49.2018.05.10.05.13.25 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 10 May 2018 05:13:27 -0700 (PDT) Date: Thu, 10 May 2018 13:12:56 +0100 From: Roman Gushchin Subject: Re: [PATCH v2] mm: fix oom_kill event handling Message-ID: <20180510121251.GA6762@castle.DHCP.thefacebook.com> References: <20180508124637.29984-1-guro@fb.com> <20180510114147.GB5325@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20180510114147.GB5325@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko 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, 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.