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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 E1F95C2D0EF for ; Fri, 17 Apr 2020 13:04:10 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id AEA0A206B9 for ; Fri, 17 Apr 2020 13:04:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AEA0A206B9 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=i-love.sakura.ne.jp Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 2DE388E0017; Fri, 17 Apr 2020 09:04:10 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 28FCC8E0001; Fri, 17 Apr 2020 09:04:10 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1A6788E0017; Fri, 17 Apr 2020 09:04:10 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0022.hostedemail.com [216.40.44.22]) by kanga.kvack.org (Postfix) with ESMTP id 01BDF8E0001 for ; Fri, 17 Apr 2020 09:04:09 -0400 (EDT) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id AEA50181AEF3E for ; Fri, 17 Apr 2020 13:04:09 +0000 (UTC) X-FDA: 76717365018.11.part25_5e652d9eda128 X-HE-Tag: part25_5e652d9eda128 X-Filterd-Recvd-Size: 4186 Received: from www262.sakura.ne.jp (www262.sakura.ne.jp [202.181.97.72]) by imf24.hostedemail.com (Postfix) with ESMTP for ; Fri, 17 Apr 2020 13:04:08 +0000 (UTC) Received: from fsav305.sakura.ne.jp (fsav305.sakura.ne.jp [153.120.85.136]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id 03HD3xrw076661; Fri, 17 Apr 2020 22:04:00 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav305.sakura.ne.jp (F-Secure/fsigk_smtp/550/fsav305.sakura.ne.jp); Fri, 17 Apr 2020 22:03:59 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/fsav305.sakura.ne.jp) Received: from [192.168.1.9] (M106072142033.v4.enabler.ne.jp [106.72.142.33]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id 03HD3xBJ076650 (version=TLSv1.2 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Fri, 17 Apr 2020 22:03:59 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Subject: Re: [RFC PATCH] mm, oom: oom ratelimit auto tuning To: Yafang Shao Cc: Michal Hocko , Andrew Morton , Linux MM , Petr Mladek , Sergey Senozhatsky References: <1586597774-6831-1-git-send-email-laoar.shao@gmail.com> <20200414073911.GC4629@dhcp22.suse.cz> <20200414143229.GN4629@dhcp22.suse.cz> <634bab6a-fee1-45b8-62af-be03062ae2bf@I-love.SAKURA.ne.jp> From: Tetsuo Handa Message-ID: <6d6c3793-d327-5d52-a1be-e5c30dc54ddf@i-love.sakura.ne.jp> Date: Fri, 17 Apr 2020 22:03:56 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2020/04/17 20:57, Yafang Shao wrote: >>>>> I justed worried that the user may complain it if too many >>>>> oom_kill_process callbacks are suppressed. >>>> >>>> This can be a real concern indeed. >> >> I'm proposing automated ratelimiting of dump_tasks() at >> http://lkml.kernel.org/r/1563360901-8277-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp . >> I believe that automated ratelimiting of dump_tasks() remains necessary >> even after printk() became asynchronous. >> > > Thanks for your information. > I haven't read your proposal carefully, but take a first glance I > think it would be a useful improvement. Thank you. That patch alone avoids just RCU stall. But https://lkml.kernel.org/r/7de2310d-afbd-e616-e83a-d75103b986c6@i-love.sakura.ne.jp and https://lkml.kernel.org/r/57be50b2-a97a-e559-e4bd-10d923895f83@i-love.sakura.ne.jp referenced from that thread allows defer printing of OOM victim candidates. And >>> Yes, printk being too sync is the real issue. If the printk an be >>> async, then we don't need to worry about it at all. >> >> I strongly disagree. dump_tasks() will needlessly fill printk() log buffer >> (and potentially loose other kernel messages due to buffer full / disk full). >> > > Yup, printk() log buffer will be a issue if the console is too slow. > After the printk() is implemented as async, I thinks it is worth to do > some optimization. my suggestion is to offload printing of OOM victim candidates to a workqueue context. Then, even after printk() became asynchronous, that workqueue waits for completion of printing to consoles for each OOM victim candidate. This way, only dump_tasks() where dumping of past OOM-killer invocations has not completed will suppress dump_tasks() from later OOM-killer invocations in a way duplicated OOM victims won't be reported for many times (and also saves printk() log buffer / disk space). I need real world reports (like your report)...