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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 10D0EC282CA for ; Sun, 27 Jan 2019 21:36:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D7F4C2133D for ; Sun, 27 Jan 2019 21:36:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727359AbfA0VgR (ORCPT ); Sun, 27 Jan 2019 16:36:17 -0500 Received: from outbound.smtp.vt.edu ([198.82.183.121]:59978 "EHLO omr2.cc.vt.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726861AbfA0VgR (ORCPT ); Sun, 27 Jan 2019 16:36:17 -0500 Received: from mr1.cc.vt.edu (mr1.cc.ipv6.vt.edu [IPv6:2607:b400:92:8300:0:31:1732:8aa4]) by omr2.cc.vt.edu (8.14.4/8.14.4) with ESMTP id x0RLaG5b009385 for ; Sun, 27 Jan 2019 16:36:16 -0500 Received: from mail-qt1-f197.google.com (mail-qt1-f197.google.com [209.85.160.197]) by mr1.cc.vt.edu (8.14.7/8.14.7) with ESMTP id x0RLaBvc027905 for ; Sun, 27 Jan 2019 16:36:16 -0500 Received: by mail-qt1-f197.google.com with SMTP id n50so18579521qtb.9 for ; Sun, 27 Jan 2019 13:36:16 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:to:cc:subject:in-reply-to:references :mime-version:date:message-id; bh=EAe1EIRGxtFb7Q9xaiUoB3dA/Fi3w2Ys5PLl0FXMnG8=; b=JVGlvgyGedFFNHInOQXpLtgE5sekdFmMsbNlF7I4Ts+l+W9rs0KMBTHcO4GoghvD06 vcDFT6n7dlmFGd1FWzI8Jp3rpTUSijRDMc5KCLu0XVkmMFcGsJFaOAKJuaXRfST/V7N0 ZIuIZlpkcTVFbnAyEpe1Ed7qFCPS4Ma3fz28zD/xIliZocusBGCCWOsSmZD+ZNg+kNDg HlLRdTr+/u4Cvf6PSJproc/NMEO2rxxwCPsBvCiRD+Jr00ifQmxgN7ZjbSI12vFaxTBg T5Y52U2oyn9FZA6eBcg+FPpIAdvnRYRvkF61VD4mrTXS45EgdJ/M4R6C55CDYM1Zjtm3 ZiVw== X-Gm-Message-State: AJcUukcr0nJdw7ZtOpAtIkGCTzD6BV4ddipPQwzO1eIAOfIPNvN8WJIi Gs7YpIjKFRb04UKSwpU/PmY8RFyv1AR0HNEmIRFyuafuX61SNDjABpIXrym+YnncRbvc83YBLuW iag5BpcR+ZCklMBix8P6aq0ZUhs5O8NQUVKY= X-Received: by 2002:a0c:ec50:: with SMTP id n16mr18623191qvq.105.1548624971483; Sun, 27 Jan 2019 13:36:11 -0800 (PST) X-Google-Smtp-Source: ALg8bN40f34/V6BL2NdwNG3rUDeL97kBUujzGyE3xy5k4svlRyqeqwc/SOXpSFCbWE+EV+q84htDmg== X-Received: by 2002:a0c:ec50:: with SMTP id n16mr18623176qvq.105.1548624971289; Sun, 27 Jan 2019 13:36:11 -0800 (PST) Received: from turing-police.cc.vt.edu ([2601:5c0:c001:4341::936]) by smtp.gmail.com with ESMTPSA id n67sm60358018qkd.95.2019.01.27.13.36.09 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Sun, 27 Jan 2019 13:36:09 -0800 (PST) From: valdis.kletnieks@vt.edu X-Google-Original-From: Valdis.Kletnieks@vt.edu X-Mailer: exmh version 2.9.0 11/07/2018 with nmh-1.7+dev To: Pavel Machek cc: 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, jack@suse.cz Subject: Re: [regression -next0117] What is kcompactd and why is he eating 100% of my cpu? In-reply-to: <20190127160027.GA9340@amd> References: <20190126200005.GB27513@amd> <12171.1548557813@turing-police.cc.vt.edu> <20190127141556.GB9565@techsingularity.net> <20190127160027.GA9340@amd> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Sun, 27 Jan 2019 16:36:34 -0500 Message-ID: <13417.1548624994@turing-police.cc.vt.edu> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Any particular diagnostic info you want me to get next time it hits? (Am currently on next-20190125, if that matters).