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=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 0CD90C33CB3 for ; Tue, 28 Jan 2020 19:45:01 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A2DC9206A2 for ; Tue, 28 Jan 2020 19:45:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="HGVP89oL" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A2DC9206A2 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 135516B0003; Tue, 28 Jan 2020 14:45:00 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 0E7976B0006; Tue, 28 Jan 2020 14:45:00 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id F3FDE6B0007; Tue, 28 Jan 2020 14:44:59 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0112.hostedemail.com [216.40.44.112]) by kanga.kvack.org (Postfix) with ESMTP id E16896B0003 for ; Tue, 28 Jan 2020 14:44:59 -0500 (EST) Received: from smtpin07.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with SMTP id 81FC82825 for ; Tue, 28 Jan 2020 19:44:59 +0000 (UTC) X-FDA: 76428071118.07.spoon61_65b99ccfd6e3d X-HE-Tag: spoon61_65b99ccfd6e3d X-Filterd-Recvd-Size: 3984 Received: from mail-ot1-f68.google.com (mail-ot1-f68.google.com [209.85.210.68]) by imf35.hostedemail.com (Postfix) with ESMTP for ; Tue, 28 Jan 2020 19:44:58 +0000 (UTC) Received: by mail-ot1-f68.google.com with SMTP id b18so13244400otp.0 for ; Tue, 28 Jan 2020 11:44:58 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=tB1X5GZ3lNFRYYLOCNfnT00dak9jJkkikUMx2JtvOc0=; b=HGVP89oL7SSzneYqHDzdZz/Zpoh17+c9v96GSV3RQTTo1hx7E+Z0TJHLbZX1hYL/Po u1ZTS8bAWqUtNHOmDND6QBWQQCY7x/G5z7kt+fTaqciRs8SOMeS7t1IRnb9NlTJzsbwB OZrdMqBzXuQH357Vb/RoiMWfOOlZb37+GG/mpyEPi840IglpwDSqZHb0tQpgduS6PmD9 khqK06mRBtaSL5620BrakSCwp6npOvP8zVHK+vAOS8IekbgMjRJttbo8Q0taLKRyvMKS bj3QGUeL2CAPGM3tpJGFOdKKhzc8dgrH8WTeuJKtU3qA2LTAcZjt/hkzQHkhUfrfTcyj Fppg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=tB1X5GZ3lNFRYYLOCNfnT00dak9jJkkikUMx2JtvOc0=; b=Nq38IB+NixzR2SuyXmTmQ18bpV5WmQBjvxw54SM9Uv9p8m32/d7LUuzK7gv8vAs72D L+JmL3W0N/a32o5UB3cvVLArOog25Tjwv9oJgk4SymUBouvOKvjAZoJznLmzhDjCQkHw wZaFFo/Dh8Szi+iAe3Dw41bqi4KibgTO+Qo+3r4gdwKuhSUflcHaqcv3rDK6SwaKjQw0 C2jP1jRJxwC4tsLKAx5qPn93KLkW3AyOSZS+HXZnC0hO4BxATrFhaj+OqzJMRv/6S56X w1kAVr+laM14PX9jCAPjD8PqWM7OeRT2zLmkBuWlncNQ7v/sgbbXG6gSd6gjkaidFMEr 5vIw== X-Gm-Message-State: APjAAAVUnFSDjNa3CLy/ybzs7xVez+yIYz1uh4LLc6H4aAnyzSacSLV2 6amHV2S6wN/Y8MDZryQcnlCsOPlLv8lBomkEdss= X-Google-Smtp-Source: APXvYqycNX8hyGUcq8BEr10UFy/BXIYuqrwDx8M+n7cAUqFKCeosbDnRGTPWIymYdYSdoXi2d1d9j80LqP5m1ix2FgA= X-Received: by 2002:a9d:7559:: with SMTP id b25mr1783817otl.189.1580240698297; Tue, 28 Jan 2020 11:44:58 -0800 (PST) MIME-Version: 1.0 References: <20200121090048.GG29276@dhcp22.suse.cz> <20200126233935.GA11536@bombadil.infradead.org> <20200127150024.GN1183@dhcp22.suse.cz> <20200127190653.GA8708@bombadil.infradead.org> <20200128081712.GA18145@dhcp22.suse.cz> <20200128083044.GB6615@bombadil.infradead.org> <20200128091352.GC18145@dhcp22.suse.cz> <20200128104857.GC6615@bombadil.infradead.org> <20200128113953.GA24244@dhcp22.suse.cz> In-Reply-To: <20200128113953.GA24244@dhcp22.suse.cz> From: Cong Wang Date: Tue, 28 Jan 2020 11:44:47 -0800 Message-ID: Subject: Re: [PATCH] mm: avoid blocking lock_page() in kcompactd To: Michal Hocko Cc: Matthew Wilcox , LKML , Andrew Morton , linux-mm , Mel Gorman , Vlastimil Babka Content-Type: text/plain; charset="UTF-8" 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 Tue, Jan 28, 2020 at 3:39 AM Michal Hocko wrote: > > On Tue 28-01-20 02:48:57, Matthew Wilcox wrote: > > Doesn't the stack trace above indicate that we're doing migration as > > the result of an allocation in add_to_page_cache_lru()? > > Which stack trace do you refer to? Because the one above doesn't show > much more beyond mem_cgroup_iter and likewise others in this email > thread. I do not really remember any stack with lock_page on the trace. I think the page is locked in add_to_page_cache_lru() by __SetPageLocked(), as the stack trace shows __add_to_page_cache_locked(). It is not yet unlocked, as it is still looping inside try_charge(). I will write a script to see if I can find the longest time spent in reclaim as you suggested. Thanks.