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=DKIMWL_WL_HIGH,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 D4C1EC352A4 for ; Mon, 10 Feb 2020 22:00:43 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8D8912072C for ; Mon, 10 Feb 2020 22:00:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="A3QgGmkm" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8D8912072C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=nvidia.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 2462D6B017F; Mon, 10 Feb 2020 17:00:43 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 1F6D46B0181; Mon, 10 Feb 2020 17:00:43 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 10C9F6B0182; Mon, 10 Feb 2020 17:00:43 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0235.hostedemail.com [216.40.44.235]) by kanga.kvack.org (Postfix) with ESMTP id EAAC06B017F for ; Mon, 10 Feb 2020 17:00:42 -0500 (EST) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 431D88248076 for ; Mon, 10 Feb 2020 22:00:42 +0000 (UTC) X-FDA: 76475587524.14.able46_6105547a1c07 X-HE-Tag: able46_6105547a1c07 X-Filterd-Recvd-Size: 3412 Received: from hqnvemgate26.nvidia.com (hqnvemgate26.nvidia.com [216.228.121.65]) by imf49.hostedemail.com (Postfix) with ESMTP for ; Mon, 10 Feb 2020 22:00:41 +0000 (UTC) Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate26.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Mon, 10 Feb 2020 14:00:26 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Mon, 10 Feb 2020 14:00:40 -0800 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Mon, 10 Feb 2020 14:00:40 -0800 Received: from [10.110.48.28] (10.124.1.5) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Mon, 10 Feb 2020 22:00:39 +0000 Subject: Re: [PATCH] mm: Improve dump_page() for compound pages To: "Kirill A. Shutemov" CC: Matthew Wilcox , , "Kirill A . Shutemov" References: <20200208044415.30012-1-willy@infradead.org> <20200210124225.56cjwblfa7njgp5o@box> <92d69132-6664-3fc3-4743-11109df0b079@nvidia.com> <20200210212125.f24n5javxkfv6uvi@box> <85d46612-b5b1-f566-7026-e4fec9166c3b@nvidia.com> <20200210215449.ao7q5x4no5y2j6pc@box> From: John Hubbard X-Nvconfidentiality: public Message-ID: <1d2ceaff-2cd5-8a03-97d0-556c1b48a69f@nvidia.com> Date: Mon, 10 Feb 2020 14:00:39 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.2 MIME-Version: 1.0 In-Reply-To: <20200210215449.ao7q5x4no5y2j6pc@box> X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL105.nvidia.com (172.20.187.12) To HQMAIL107.nvidia.com (172.20.187.13) Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1581372026; bh=NQ8v3W2HGbns9RJnXL9O8856EojF+o/iVy42S0xeQOw=; h=X-PGP-Universal:Subject:To:CC:References:From:X-Nvconfidentiality: Message-ID:Date:User-Agent:MIME-Version:In-Reply-To: X-Originating-IP:X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=A3QgGmkmds7oyhUKeso2v5QVqLPj6FqQo5W7MXyN1MaFMQJQW5wU2G49RnmzfVPta y/0QJwWnHxqsPfUTs/9/ShxCTn27v2hOZMiel0P/LbLUmugmfQURG0bXfdVbQ0tjva Fkcj2WnrNPbA/CHDIuKDPBa6+L/Xar8ym96JESkeBs+72A4zxk/XuWFu0vvXKbi1j/ tOYqrDAqg3f5d+OmB9nE0yS7Q9kGIuo0AT8Th0AVyE/Fps+PT84w2MGmrdVlwNi1OO eLpukTfhLtwlHE5UYGidD+m+ZhLpWQ4828D/ee6QMJTSEmO0S54VvlTra9ZDjO/mUo c1Mq9b4VT5hTg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000077, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2/10/20 1:54 PM, Kirill A. Shutemov wrote: > On Mon, Feb 10, 2020 at 01:33:22PM -0800, John Hubbard wrote: >>> PageSlab() can be called for the head page. >> >> >> It's not clear to me whether it's safer to use the...user-provided page, or the >> head page, for checking PageSlab()--it's probably set on both head and non-head >> pages, right? > > PageSlab() will call compound_head() inside. > >> I guess you're saying it should be like this: >> >> mapcount = PageSlab(head) ? 0 : page_mapcount(page); >> >> ...yes? > > Yes. > OK very good, thanks for walking me through it. :) Matthew, if you like I'll just fix it up like that for my v6 posting of the patchset, since it's such a small change. thanks, -- John Hubbard NVIDIA