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=-2.6 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,URIBL_BLOCKED, 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 A5EB1C282C8 for ; Mon, 28 Jan 2019 10:57:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 649B320882 for ; Mon, 28 Jan 2019 10:57:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="IWEd45GC" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726772AbfA1K52 (ORCPT ); Mon, 28 Jan 2019 05:57:28 -0500 Received: from mail-pf1-f194.google.com ([209.85.210.194]:42535 "EHLO mail-pf1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726415AbfA1K52 (ORCPT ); Mon, 28 Jan 2019 05:57:28 -0500 Received: by mail-pf1-f194.google.com with SMTP id 64so7819439pfr.9 for ; Mon, 28 Jan 2019 02:57:27 -0800 (PST) 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=JVYWtGcMYfFrMfJPBE9msQ46Zw2VTYoiELafs7+LoJc=; b=IWEd45GCMqZObIwFOhKrEAxo92cSxfHp/ZJiXp0hgf1CSZa312empmTbYb+/w9YTqf zeenJOs95bvTnIyOWQ4+nBec2Ea76OcmiVaz0CbtM+KvmNf+Pt6KywNkMQCu3Jdf2sZe jaUZlSF8qLoTMIh+Mf7Eakv/gppQwvDpIQFkyYn90tOyK3SAwBIzqzb+JIN/k7ezypNV SKcNf7EGAtaXu36vQxUcnU4cnieF/DS2uQHZpG1TDdpMmbOy8iUfJNChs5mizX4z01pH zLzKDvCH8kRjgHRx4k+I8/ELhekVxXoKPoFHBynGwxUfpyPKZ0Fz9MmQx06pvEvbgreA mGCA== 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=JVYWtGcMYfFrMfJPBE9msQ46Zw2VTYoiELafs7+LoJc=; b=K8AjHSWJrK82BOFSGqLALMOXxtILKOU5gP9sNSE512tXjrVv7DCKWnbuz/4fr57l3S rvPL7AMx/rHFDYf9GYS5Jkb7wBYDl9nEL2ZNEHAMWxHyjG2aMgtLDz15QJ4JhCTrDK2e shLnWTdXkflnIFbSW/8HXhwoKy5IMSDSCeTJDWMnjDfps10XEC0wCUU0N9lSsV2WO1ME KmH23FgCA9SRswwTF3gOk+NkzIwwmThmS5UqJ85f8RVwjK5GyG1jBUFrvt3WeTBLMCM5 O5DJuNBvLyNwnU0v8E6TTaSU4XJJhCwdA7hR7rUA5Evokl0ig2kPoDrDhawnCRVFWVca 5UjQ== X-Gm-Message-State: AJcUukeOCUk5IIq3BLbFZweUau0tFj0VHlvAWQpwEYwKsikR/1BouOp/ tuYznhn8rJmO1olBnXHU5Eo= X-Google-Smtp-Source: ALg8bN7cKZzqabNZqs7bfU5SRdpB/X6QKQSgIjrpBZhNELkoV9wtMkpVAEMJ1RTqOzkOyFDR5Csulg== X-Received: by 2002:a63:d40a:: with SMTP id a10mr19120353pgh.394.1548673047647; Mon, 28 Jan 2019 02:57:27 -0800 (PST) Received: from localhost ([175.223.18.40]) by smtp.gmail.com with ESMTPSA id s190sm43732837pfb.103.2019.01.28.02.57.25 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 28 Jan 2019 02:57:26 -0800 (PST) Date: Mon, 28 Jan 2019 19:57:23 +0900 From: Sergey Senozhatsky To: Jan Kara Cc: valdis.kletnieks@vt.edu, Pavel Machek , Mel Gorman , kernel list , Andrew Morton , vbabka@suse.cz, aarcange@redhat.com, rientjes@google.com, mhocko@kernel.org, zi.yan@cs.rutgers.edu, hannes@cmpxchg.org Subject: Re: [regression -next0117] What is kcompactd and why is he eating 100% of my cpu? Message-ID: <20190128105723.GA10453@jagdpanzerIV> References: <20190126200005.GB27513@amd> <12171.1548557813@turing-police.cc.vt.edu> <20190127141556.GB9565@techsingularity.net> <20190127160027.GA9340@amd> <13417.1548624994@turing-police.cc.vt.edu> <20190128091627.GA27972@quack2.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190128091627.GA27972@quack2.suse.cz> User-Agent: Mutt/1.11.2 (2019-01-07) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (01/28/19 10:16), Jan Kara wrote: > On Sun 27-01-19 16:36:34, valdis.kletnieks@vt.edu wrote: > > On Sun, 27 Jan 2019 17:00:27 +0100, Pavel Machek said: > > > > > I've noticed this as well on earlier kernels (next-20181224 to 20190115) > > > > > Some more info: > > > > > 1) echo 3 > /proc/sys/vm/drop_caches unwedges kcompactd in 1-3 seconds. > > > > This aspect is curious as it indicates that kcompactd could potentially > > > > be infinite looping but it's not something I've experienced myself. By > > > > any chance is there a preditable reproduction case for this? > > > > > > I seen it exactly once, so not sure how reproducible this is. x86-32 > > > machine, running chromium browser, so yes, there was some swapping > > > involved. > > > > I don't have a surefire replicator, but my laptop (x86_64, so it's not a 32-bit > > only issue) triggers it fairly often, up to multiple times a day. Doesn't seem to > > be just the Chrome browser that triggers it - usually I'm doing other stuff as > > well, like a compile or similar. The fact that 'drop_caches' clears it makes me > > wonder if we're hitting a corner case where cache data isn't being automatically > > cleared and clogging something up. > > So my buffer_migrate_page_norefs() is certainly buggy in its current > incarnation (as a result block device page cache is not migratable at all). > I've sent Andrew a patch over week ago but so far it got ignored. The patch > is attached, can you give it a try whether it changes something for you? > Thanks! Hello Jan, Just for note, I'm seeing the same problems on my x86 box [1]. Don't have a reproducer for the issue yet, but will try to test your patch. Thanks. [1] https://lore.kernel.org/lkml/20190128085747.GA14454@jagdpanzerIV/T/#u -ss