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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 5103CC6783C for ; Fri, 12 Oct 2018 12:58:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0AFE52086A for ; Fri, 12 Oct 2018 12:58:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0AFE52086A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=i-love.sakura.ne.jp 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 S1728574AbeJLUam (ORCPT ); Fri, 12 Oct 2018 16:30:42 -0400 Received: from www262.sakura.ne.jp ([202.181.97.72]:23055 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727838AbeJLUam (ORCPT ); Fri, 12 Oct 2018 16:30:42 -0400 Received: from fsav302.sakura.ne.jp (fsav302.sakura.ne.jp [153.120.85.133]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id w9CCwJfq003805; Fri, 12 Oct 2018 21:58:19 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav302.sakura.ne.jp (F-Secure/fsigk_smtp/530/fsav302.sakura.ne.jp); Fri, 12 Oct 2018 21:58:19 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/530/fsav302.sakura.ne.jp) Received: from [192.168.1.8] (softbank060157066051.bbtec.net [60.157.66.51]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id w9CCwJra003790 (version=TLSv1.2 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Fri, 12 Oct 2018 21:58:19 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Subject: Re: [RFC PATCH] memcg, oom: throttle dump_header for memcg ooms without eligible tasks To: Johannes Weiner Cc: Michal Hocko , 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 References: <000000000000dc48d40577d4a587@google.com> <20181010151135.25766-1-mhocko@kernel.org> <20181012112008.GA27955@cmpxchg.org> <20181012120858.GX5873@dhcp22.suse.cz> <9174f087-3f6f-f0ed-6009-509d4436a47a@i-love.sakura.ne.jp> <20181012124137.GA29330@cmpxchg.org> From: Tetsuo Handa Message-ID: <0417c888-d74e-b6ae-a8f0-234cbde03d38@i-love.sakura.ne.jp> Date: Fri, 12 Oct 2018 21:58:19 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20181012124137.GA29330@cmpxchg.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Calling printk() people. ;-) On 2018/10/12 21:41, Johannes Weiner wrote: > On Fri, Oct 12, 2018 at 09:10:40PM +0900, Tetsuo Handa wrote: >> On 2018/10/12 21:08, Michal Hocko wrote: >>>> So not more than 10 dumps in each 5s interval. That looks reasonable >>>> to me. By the time it starts dropping data you have more than enough >>>> information to go on already. >>> >>> Yeah. Unless we have a storm coming from many different cgroups in >>> parallel. But even then we have the allocation context for each OOM so >>> we are not losing everything. Should we ever tune this, it can be done >>> later with some explicit examples. >>> >>>> Acked-by: Johannes Weiner >>> >>> Thanks! I will post the patch to Andrew early next week. >>> >> >> How do you handle environments where one dump takes e.g. 3 seconds? >> Counting delay between first message in previous dump and first message >> in next dump is not safe. Unless we count delay between last message >> in previous dump and first message in next dump, we cannot guarantee >> that the system won't lockup due to printk() flooding. > > How is that different from any other printk ratelimiting? If a dump > takes 3 seconds you need to fix your console. It doesn't make sense to > design KERN_INFO messages for the slowest serial consoles out there. You can't fix the console. It is a hardware limitation. > > That's what we did, btw. We used to patch out the OOM header because > our serial console was so bad, but obviously that's not a generic > upstream solution. We've since changed the loglevel on the serial and > use netconsole[1] for the chattier loglevels. > > [1] https://github.com/facebook/fbkutils/tree/master/netconsd >