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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable 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 DDBC3C10F0E for ; Sun, 7 Apr 2019 16:07:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B6C602083E for ; Sun, 7 Apr 2019 16:07:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726573AbfDGQG5 (ORCPT ); Sun, 7 Apr 2019 12:06:57 -0400 Received: from outgoing-auth-1.mit.edu ([18.9.28.11]:55752 "EHLO outgoing.mit.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726329AbfDGQG5 (ORCPT ); Sun, 7 Apr 2019 12:06:57 -0400 Received: from callcc.thunk.org (189.sub-97-41-144.myvzw.com [97.41.144.189]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id x37G6eF3011084 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Sun, 7 Apr 2019 12:06:47 -0400 Received: by callcc.thunk.org (Postfix, from userid 15806) id DA506421A12; Sun, 7 Apr 2019 11:55:21 -0400 (EDT) Date: Sun, 7 Apr 2019 11:55:21 -0400 From: "Theodore Ts'o" To: Liu Xiang Cc: linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, adilger.kernel@dilger.ca, liuxiang_1999@126.com Subject: Re: [PATCH v2] ext4: fix prefetchw of NULL page Message-ID: <20190407155521.GL18897@mit.edu> Mail-Followup-To: Theodore Ts'o , Liu Xiang , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, adilger.kernel@dilger.ca, liuxiang_1999@126.com References: <1554019894-11041-1-git-send-email-liu.xiang6@zte.com.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1554019894-11041-1-git-send-email-liu.xiang6@zte.com.cn> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Sun, Mar 31, 2019 at 04:11:34PM +0800, Liu Xiang wrote: > In ext4_mpage_readpages(), if the parameter pages is not NULL, another > parameter page is NULL. At the first time prefetchw(&page->flags) > works on NULL. From second time, prefetchw(&page->flags) always works on > the last consumed page. This might do little improvment for handling > current page. So prefetchw() should be called while the page pointer > has just been updated. Thanks, applied. - Ted