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 3AB59C43441 for ; Wed, 10 Oct 2018 11:48:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E2A4820858 for ; Wed, 10 Oct 2018 11:48:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="oYfuJZ21" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E2A4820858 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 S1726862AbeJJTKg (ORCPT ); Wed, 10 Oct 2018 15:10:36 -0400 Received: from mail-pl1-f194.google.com ([209.85.214.194]:39300 "EHLO mail-pl1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726206AbeJJTKg (ORCPT ); Wed, 10 Oct 2018 15:10:36 -0400 Received: by mail-pl1-f194.google.com with SMTP id w14-v6so2418206plp.6 for ; Wed, 10 Oct 2018 04:48:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:date:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=F9rX++vGHuUVTHBx+RFzH2Dn0pBlm6wwSZMASPuD7SI=; b=oYfuJZ21idS0i7mMiLtpFk/WQxesC0htAnq2gDyArprwfbFmyu62Rd6Q38SuWJOtC0 HbQ71bkTg1dcxeaWl+dGmypjd2Uulla2PnIlRhb2iBzZTholHO2zM+1031mUntPfcmvu q1U4uiK9D9G2gF22DMhLK5TueCdA3AyGEmWNwXR+gT7M2zCUOOapLZtTuMt0Hn3PUM91 Taukb/XtJ2SXtgXTW3x1Lk+I3xoJvgFWMGE3rUGaS6JC6Hl3BWBZ6gUioJC3DoSa9uZ0 9+XzvMghUDfxZfY1kfhb/D2w7j4y2/ET1f9yLCNQV4N8iTiLb1t+zOvpezbkrRepexVf Hr0Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:date:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=F9rX++vGHuUVTHBx+RFzH2Dn0pBlm6wwSZMASPuD7SI=; b=Qw+sRcP1F8Da51QhQ+G2r8PDFobTtk9HZl1jWRnuWtWpiEbUuACw3JYXusnL/JhM48 mWovRTLi7rEDaLAD+RWMMHt8rKvV5ovkh0bvgSSYEnizZcrjayys6P5anM49+sc+xN7n ravy2ge+ItyYRzfcq3o96zT2BBsjcTgtf6hXUFa12rbHDQpuXVnGrS1iOGnk8Usf2sJE 99dNeW0GJiMWfDIy7ZRHH4uuxgz++uXacvUxMl1PqsSQJdiowAQ+V1PBMCrCGCQfDSBN yNaf1qbj+JUuEzAVzDtlJ0hIKwt0TU0D5DdrUHivR9FQxpJf9xEA/96t/oLNN8zufjR7 t84A== X-Gm-Message-State: ABuFfohRC5Z57pZCbu9q07LeNQeYj7lcjh9aqbwtupgQiECkjaQxAynw C4mEQozOcLaGlhMlc5OBI5c= X-Google-Smtp-Source: ACcGV607OTzFS0Xi66e5drsNYy0z3+PEOqgMHqoFPAYlNksWU8NOiG+pmNXo4yhh0tUM+vDSyCf3Mg== X-Received: by 2002:a17:902:934a:: with SMTP id g10-v6mr33344138plp.288.1539172129172; Wed, 10 Oct 2018 04:48:49 -0700 (PDT) Received: from localhost ([121.137.63.184]) by smtp.gmail.com with ESMTPSA id c124-v6sm38452056pfa.119.2018.10.10.04.48.45 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 10 Oct 2018 04:48:48 -0700 (PDT) From: Sergey Senozhatsky X-Google-Original-From: Sergey Senozhatsky Date: Wed, 10 Oct 2018 20:48:33 +0900 To: Michal Hocko Cc: Tetsuo Handa , syzbot , hannes@cmpxchg.org, akpm@linux-foundation.org, guro@fb.com, kirill.shutemov@linux.intel.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, rientjes@google.com, syzkaller-bugs@googlegroups.com, yang.s@alibaba-inc.com, Sergey Senozhatsky , Sergey Senozhatsky , Petr Mladek Subject: Re: INFO: rcu detected stall in shmem_fault Message-ID: <20181010114833.GB3949@tigerII.localdomain> References: <000000000000dc48d40577d4a587@google.com> <201810100012.w9A0Cjtn047782@www262.sakura.ne.jp> <20181010085945.GC5873@dhcp22.suse.cz> <20181010113500.GH5873@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181010113500.GH5873@dhcp22.suse.cz> 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 (10/10/18 13:35), Michal Hocko wrote: > > Just flooding out of memory messages can trigger RCU stall problems. > > For example, a severe skbuff_head_cache or kmalloc-512 leak bug is causing > > [...] > > Quite some of them, indeed! I guess we want to rate limit the output. > What about the following? A bit unrelated, but while we are at it: I like it when we rate-limit printk-s that lookup the system. But it seems that default rate-limit values are not always good enough, DEFAULT_RATELIMIT_INTERVAL / DEFAULT_RATELIMIT_BURST can still be too verbose. For instance, when we have a very slow IPMI emulated serial console -- e.g. baud rate at 57600. DEFAULT_RATELIMIT_INTERVAL and DEFAULT_RATELIMIT_BURST can add new OOM headers and backtraces faster than we evict them. Does it sound reasonable enough to use larger than default rate-limits for printk-s in OOM print-outs? OOM reports tend to be somewhat large and the reported numbers are not always *very* unique. What do you think? -ss