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_1 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 233D3CA9EB6 for ; Wed, 23 Oct 2019 15:01:15 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D8D3821872 for ; Wed, 23 Oct 2019 15:01:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="UEm10kwh" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D8D3821872 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 894AA6B0003; Wed, 23 Oct 2019 11:01:14 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8457A6B0006; Wed, 23 Oct 2019 11:01:14 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 732E26B0007; Wed, 23 Oct 2019 11:01:14 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0072.hostedemail.com [216.40.44.72]) by kanga.kvack.org (Postfix) with ESMTP id 4CEA66B0003 for ; Wed, 23 Oct 2019 11:01:14 -0400 (EDT) Received: from smtpin12.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id E564418088935 for ; Wed, 23 Oct 2019 15:01:13 +0000 (UTC) X-FDA: 76075362426.12.scene99_7f08f56b92961 X-HE-Tag: scene99_7f08f56b92961 X-Filterd-Recvd-Size: 3464 Received: from us-smtp-delivery-1.mimecast.com (us-smtp-1.mimecast.com [205.139.110.61]) by imf35.hostedemail.com (Postfix) with ESMTP for ; Wed, 23 Oct 2019 15:01:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1571842872; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=cdptM1wjryYnQhJm9RmuX5FaBmrJ2EY+9SJ+YV4u0fQ=; b=UEm10kwh/Gl+wyW634T5RyoDn0MZNkGl6QXiPnJTq67e2nRucJWzy7+Vk7bzmz9YfuzvZx osVKyGYUCkAhh+kFfcMclZAbeS9g5KOL1xx1q5cZdt9SrXCr9MkkIDCmze+VW1D9uaUXUy n9A/C396JBXuWa1xXYKHGEE5DsY/6uw= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-226-Y09mMa8JNFO1Wvt2DH_ATQ-1; Wed, 23 Oct 2019 11:01:08 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 281081005500; Wed, 23 Oct 2019 15:01:06 +0000 (UTC) Received: from llong.remote.csb (dhcp-17-59.bos.redhat.com [10.18.17.59]) by smtp.corp.redhat.com (Postfix) with ESMTP id C8AA919C77; Wed, 23 Oct 2019 15:01:04 +0000 (UTC) Subject: Re: [PATCH] mm/vmstat: Reduce zone lock hold time when reading /proc/pagetypeinfo To: Qian Cai , 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 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> From: Waiman Long Organization: Red Hat Message-ID: Date: Wed, 23 Oct 2019 11:01:04 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <1571842093.5937.84.camel@lca.pw> Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-MC-Unique: Y09mMa8JNFO1Wvt2DH_ATQ-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable 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 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 wil= l 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. Cheers, Longman