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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_2 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 82B82CA9EB6 for ; Wed, 23 Oct 2019 15:05:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5403E21872 for ; Wed, 23 Oct 2019 15:05:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lca.pw header.i=@lca.pw header.b="dpZNxdHO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2406476AbfJWPFx (ORCPT ); Wed, 23 Oct 2019 11:05:53 -0400 Received: from mail-qk1-f193.google.com ([209.85.222.193]:34320 "EHLO mail-qk1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390530AbfJWPFw (ORCPT ); Wed, 23 Oct 2019 11:05:52 -0400 Received: by mail-qk1-f193.google.com with SMTP id f18so19455917qkm.1 for ; Wed, 23 Oct 2019 08:05:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=lca.pw; s=google; h=message-id:subject:from:to:cc:date:in-reply-to:references :mime-version:content-transfer-encoding; bh=SLjhfsX3TyBTxi+fadpIVv6MU4Vj9o2A3I+zpLB2nks=; b=dpZNxdHOy4bVG236Wqmg3LjjIOL2Pb9HsX5jejGqUUraI6L7k/lsMZBeRntTpSU5Zr 2mubf6q7jQDqSpXmaO/S2FbhM+f3yB+wYQ6jQ6ip80Aq/icFyQ6jJOIr2NmmAeMEQCEe D2gmG1kN+UrdPCg4s+WBcPnkZ+W6uxER0eOfSKinvsCmgJCdRAPxvaUMNxdRVBlcoTKW RUJvGibJhkDLc+eIv6fhxBdEZzRuMWmhunkFVKX5RyYb2djcEou9Se3RJAzmn1s9LqEG Cr/I82a6yc29yyiX9frfgfKomvb7oNbcSG45U8PBW5Ggg81miqNowwQ1jWN5KoDfhPra HL0Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:subject:from:to:cc:date:in-reply-to :references:mime-version:content-transfer-encoding; bh=SLjhfsX3TyBTxi+fadpIVv6MU4Vj9o2A3I+zpLB2nks=; b=X11TV6QkcAURBTJger3h3ULAlhyXj6lCYBThdbcH/XsjKouC/rzutP97YjoWptfPBB UynGyTgo0hXBBlNsj0AcROnD7/BDmuFO9F67h59QIdGUf6Q6WQDmaDPtJkk5QF16hEHy ia73uUFlMy46sZp/ZaELOBN0P27Quzc5S8meFV6vw6HG7SEXg34sub2Ywws2JBtACnKj DO3ax0/GkSgBdj5xKGP4O31l6iEFHUE8681v+H5oNTZM2IeDw8uWzTld5SNMmSrKWMvR FfY48OUEjT0GRbQrcL73Nm6M1ttx30VqMe2UVfoKXtu8jjIQ1iVCB79YRdcv6s9ISPxy oLgA== X-Gm-Message-State: APjAAAVTUcBXtWa65F9EkF5sAJ+C5IAvesvuPirIR+JXEiIQ2cbYn7NV BDo3RiDja++16UqCLuemtjdxmQ== X-Google-Smtp-Source: APXvYqz/FhzYp8GGto8Tw5/JjylZYPd63dPTZ0r6aLPjuXrJ8f52Q9xo89ZFsXl2ek0p5+cCXZ5Ieg== X-Received: by 2002:a37:8dc6:: with SMTP id p189mr8546331qkd.421.1571843151739; Wed, 23 Oct 2019 08:05:51 -0700 (PDT) Received: from dhcp-41-57.bos.redhat.com (nat-pool-bos-t.redhat.com. [66.187.233.206]) by smtp.gmail.com with ESMTPSA id 18sm8420462qky.109.2019.10.23.08.05.50 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 23 Oct 2019 08:05:51 -0700 (PDT) Message-ID: <1571843149.5937.86.camel@lca.pw> Subject: Re: [PATCH] mm/vmstat: Reduce zone lock hold time when reading /proc/pagetypeinfo From: Qian Cai To: Waiman Long , Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Johannes Weiner , Michal Hocko , Roman Gushchin , Vlastimil Babka , Konstantin Khlebnikov , Jann Horn , Song Liu , Greg Kroah-Hartman , Rafael Aquini Date: Wed, 23 Oct 2019 11:05:49 -0400 In-Reply-To: References: <20191022162156.17316-1-longman@redhat.com> <20191022145902.d9c4a719c0b32175e06e4eee@linux-foundation.org> <2236495a-ead0-e08e-3fb6-f3ab906b75b6@redhat.com> <1571842093.5937.84.camel@lca.pw> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.22.6 (3.22.6-10.el7) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2019-10-23 at 11:01 -0400, Waiman Long wrote: > On 10/23/19 10:48 AM, Qian Cai wrote: > > > > this still isn't a bulletproof fix. Maybe just terminate the list > > > > walk if freecount reaches 1024. Would anyone really care? > > > > > > > > Sigh. I wonder if anyone really uses this thing for anything > > > > important. Can we just remove it all? > > > > > > > > > > Removing it will be a breakage of kernel API. > > > > Who cares about breaking this part of the API that essentially nobody will use > > this file? > > > > There are certainly tools that use /proc/pagetypeinfo and this is how > the problem is found. I am not against removing it, but we have to be > careful and deprecate it in way that minimize user impact. What are those tools?