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=-2.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,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 A0050C004D3 for ; Tue, 23 Oct 2018 00:47:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9F9CF20665 for ; Tue, 23 Oct 2018 00:47:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Z7kaJwbR" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9F9CF20665 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com 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 S1727030AbeJWJIZ (ORCPT ); Tue, 23 Oct 2018 05:08:25 -0400 Received: from mail-pf1-f196.google.com ([209.85.210.196]:34186 "EHLO mail-pf1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725768AbeJWJIZ (ORCPT ); Tue, 23 Oct 2018 05:08:25 -0400 Received: by mail-pf1-f196.google.com with SMTP id f78-v6so14992571pfe.1 for ; Mon, 22 Oct 2018 17:47:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=jVfDl9QShSOhyDU0OnYMokfNpBf7N9t+QZFMXfBBnM8=; b=Z7kaJwbRAuOG2PnINwZYQwW2YG6lbfoOymU+ESuodEK6rBr896Qbc7hOj/CUyhiSBr rZr4VOCvdqPkPt9P5ufM0sPFbEB69vW5Qfaf0yB9GC1uuuUEhw4eiXwBsjrQ/nNwyCXP UtSc9gjEw7w9bx0d6xGQFzjVnSMdrRyGfT52kE3ECgtEQ5pJZw2DnisvebZObvnGH77k 2Ym3baRg9MG40BXsJpDuvbytYoTcHd10ygHK8vwg6iEKSWs5CTaZ+HvutORNRnrWuqhM 7wppaoZN7mbwB8YI4D68zbIbi6WeP5wVEluURcNIIpQfIFg+XWNQngbmQKJiAmib8N9R aqtg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=jVfDl9QShSOhyDU0OnYMokfNpBf7N9t+QZFMXfBBnM8=; b=AbKazO4h2MkFRC1aPgicQMc+HgR1/HXZUX0cdjlLwHhAMXUz7K1tunQI72roG3LcTx HjxC5PJSVcCuboMlY3c0MhjkmZ+15PSH1C0QqBBRDrixianuYKbWDnP657urm7j8ANmY 4GqtYuUGrLbRTQ7KpiqZOyLiN8BKqP8z8NA2ZnRL804CgXvJ+dtO27HOrQ50MshhRk7L 3LdW/iB7ywVVUL+htEIidhmIqEFfxO0kNNm98c8ZD6czO6C3CcIhImETdhAhz9q87PBa a4iEcLojQCO0j3X2z5Mcq9QKmg91Pguh6xgXGYtby1wIiYDROB7dmbngn2FxECZXzf/g nnYg== X-Gm-Message-State: ABuFfoiacXpWAWrq/CQQ3iAva+eOIaMvegZF1E88qJs/xPhT+eqD38mc WVhBHnra4RtFAE1u08TXZrjgTNMb X-Google-Smtp-Source: ACcGV61t/XDgypTFoBxaXW7WA0HUsP5z0yilmBV+1U6BqEIQ8MK7keN2aaSKo08wczN+Hd1iJl0NNw== X-Received: by 2002:a62:32c4:: with SMTP id y187-v6mr47649710pfy.4.1540255651053; Mon, 22 Oct 2018 17:47:31 -0700 (PDT) Received: from localhost ([175.223.11.183]) by smtp.gmail.com with ESMTPSA id m19-v6sm11979305pgv.93.2018.10.22.17.47.29 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 22 Oct 2018 17:47:29 -0700 (PDT) Date: Tue, 23 Oct 2018 09:47:26 +0900 From: Sergey Senozhatsky To: Tetsuo Handa Cc: Sergey Senozhatsky , Michal Hocko , 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 , Petr Mladek , Sergey Senozhatsky , Steven Rostedt , syzbot , Calvin Owens Subject: Re: [PATCH v3] mm: memcontrol: Don't flood OOM messages with no eligible task. Message-ID: <20181023004726.GA4612@jagdpanzerIV> References: <201810180246.w9I2koi3011358@www262.sakura.ne.jp> <20181018042739.GA650@jagdpanzerIV> <201810180526.w9I5QvVn032670@www262.sakura.ne.jp> <20181018061018.GB650@jagdpanzerIV> <20181018075611.GY18839@dhcp22.suse.cz> <20181018081352.GA438@jagdpanzerIV> <2c2b2820-e6f8-76c8-c431-18f60845b3ab@i-love.sakura.ne.jp> <20181018235427.GA877@jagdpanzerIV> <5d472476-7852-f97b-9412-63536dffaa0e@i-love.sakura.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5d472476-7852-f97b-9412-63536dffaa0e@i-love.sakura.ne.jp> 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 (10/19/18 19:35), Tetsuo Handa wrote: > > > > OK, that's a fair point. There was a patch from FB, which would allow us > > to set a log_level on per-console basis. So the noise goes to heav^W net > > console; only critical stuff goes to the serial console (if I recall it > > correctly). I'm not sure what happened to that patch, it was a while ago. > > I'll try to find that out. > > Per a console loglevel setting would help for several environments. > But syzbot environment cannot count on netconsole. We can't expect that > unlimited printk() will become safe. This target is moving too fast :) RCU stall -> user interaction -> syzbot I talked to Calvin Owens (who's working on the per-console loglevel patch set; CC-ed) and Calvin said that "It's in-progress". So we probably will have this functionality one day. That's all we can do from printk side wrt user-interaction problem. > > The problem you are talking about is not MM specific. You can have a > > faulty SCSI device, corrupted FS, and so and on. > > "a faulty SCSI device, corrupted FS, and so and on" are reporting problems > which will complete a request. They can use (and are using) ratelimit, > aren't they? Looking at scsi_request_fn(), the answer is probably "sure they can; but no, they aren't". In majority of cases the reason we replace printk with printk_ratelimit is because someone reports a stall or a lockup. Otherwise, people use printk(), which is absolutely fine. -ss