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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 5269DC00523 for ; Fri, 3 Jan 2020 23:39:31 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id F371921835 for ; Fri, 3 Jan 2020 23:39:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F371921835 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 5E5E58E0005; Fri, 3 Jan 2020 18:39:28 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 596388E0003; Fri, 3 Jan 2020 18:39:28 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 48DE98E0005; Fri, 3 Jan 2020 18:39:28 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0155.hostedemail.com [216.40.44.155]) by kanga.kvack.org (Postfix) with ESMTP id 2F0EB8E0003 for ; Fri, 3 Jan 2020 18:39:28 -0500 (EST) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with SMTP id CDC30442B for ; Fri, 3 Jan 2020 23:39:27 +0000 (UTC) X-FDA: 76337941974.20.brain01_6fa45f6e7ab25 X-HE-Tag: brain01_6fa45f6e7ab25 X-Filterd-Recvd-Size: 2472 Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by imf10.hostedemail.com (Postfix) with ESMTP for ; Fri, 3 Jan 2020 23:39:26 +0000 (UTC) X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 03 Jan 2020 15:39:25 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,392,1571727600"; d="scan'208";a="252740373" Received: from richard.sh.intel.com (HELO localhost) ([10.239.159.54]) by fmsmga002.fm.intel.com with ESMTP; 03 Jan 2020 15:39:23 -0800 Date: Sat, 4 Jan 2020 07:39:25 +0800 From: Wei Yang To: David Rientjes Cc: Wei Yang , hannes@cmpxchg.org, mhocko@kernel.org, vdavydov.dev@gmail.com, akpm@linux-foundation.org, kirill.shutemov@linux.intel.com, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, yang.shi@linux.alibaba.com Subject: Re: [RFC PATCH] mm: thp: grab the lock before manipulation defer list Message-ID: <20200103233925.GA3678@richard> Reply-To: Wei Yang References: <20200103143407.1089-1-richardw.yang@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) 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 Fri, Jan 03, 2020 at 11:29:06AM -0800, David Rientjes wrote: >On Fri, 3 Jan 2020, Wei Yang wrote: > >> As all the other places, we grab the lock before manipulate the defer list. >> Current implementation may face a race condition. >> >> Fixes: 87eaceb3faa5 ("mm: thp: make deferred split shrinker memcg aware") >> >> Signed-off-by: Wei Yang >> >> --- >> I notice the difference during code reading and just confused about the >> difference. No specific test is done since limited knowledge about cgroup. >> >> Maybe I miss something important? > >The check for !list_empty(page_deferred_list(page)) must certainly be >serialized with doing list_del_init(page_deferred_list(page)). > Hi David Would you mind giving more information? You mean list_empty and list_del_init is atomic? -- Wei Yang Help you, Help me