From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5748AC04AA5 for ; Mon, 15 Oct 2018 11:24:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1026920881 for ; Mon, 15 Oct 2018 11:24:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1026920881 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726571AbeJOTJW (ORCPT ); Mon, 15 Oct 2018 15:09:22 -0400 Received: from mx2.suse.de ([195.135.220.15]:39596 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726357AbeJOTJV (ORCPT ); Mon, 15 Oct 2018 15:09:21 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 367D7AD49; Mon, 15 Oct 2018 11:24:30 +0000 (UTC) Date: Mon, 15 Oct 2018 13:24:27 +0200 From: Michal Hocko To: Tetsuo Handa Cc: Johannes Weiner , linux-mm@kvack.org, syzkaller-bugs@googlegroups.com, guro@fb.com, kirill.shutemov@linux.intel.com, linux-kernel@vger.kernel.org, rientjes@google.com, yang.s@alibaba-inc.com, Andrew Morton , Sergey Senozhatsky , Petr Mladek , Sergey Senozhatsky , Steven Rostedt Subject: Re: [RFC PATCH] memcg, oom: throttle dump_header for memcg ooms without eligible tasks Message-ID: <20181015112427.GI18839@dhcp22.suse.cz> References: <20181012112008.GA27955@cmpxchg.org> <20181012120858.GX5873@dhcp22.suse.cz> <9174f087-3f6f-f0ed-6009-509d4436a47a@i-love.sakura.ne.jp> <20181012124137.GA29330@cmpxchg.org> <0417c888-d74e-b6ae-a8f0-234cbde03d38@i-love.sakura.ne.jp> <20181013112238.GA762@cmpxchg.org> <20181015081934.GD18839@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 15-10-18 19:57:35, Tetsuo Handa wrote: > On 2018/10/15 17:19, Michal Hocko wrote: > > As so many dozens of times before, I will point you to an incremental > > nature of changes we really prefer in the mm land. We are also after a > > simplicity which your proposal lacks in many aspects. You seem to ignore > > that general approach and I have hard time to consider your NAK as a > > relevant feedback. Going to an extreme and basing a complex solution on > > it is not going to fly. No killable process should be a rare event which > > requires a seriously misconfigured memcg to happen so wildly. If you can > > trigger it with a normal user privileges then it would be a clear bug to > > address rather than work around with printk throttling. > > > > I can trigger 200+ times / 900+ lines / 69KB+ of needless OOM messages > with a normal user privileges. This is a lot of needless noise/delay. I am pretty sure you have understood the part of my message you have chosen to not quote where I have said that the specific rate limitting decisions can be changed based on reasonable configurations. There is absolutely zero reason to NAK a natural decision to unify the throttling and cook a per-memcg way for a very specific path instead. > No killable process is not a rare event, even without root privileges. > > [root@ccsecurity kumaneko]# time ./a.out > Killed > > real 0m2.396s > user 0m0.000s > sys 0m2.970s > [root@ccsecurity ~]# dmesg | grep 'no killable' | wc -l > 202 > [root@ccsecurity ~]# dmesg | wc > 942 7335 70716 OK, so this is 70kB worth of data pushed throug the console. Is this really killing any machine? -- Michal Hocko SUSE Labs