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 670B5C3F68F for ; Mon, 6 Jan 2020 01:20:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3BBEC217F4 for ; Mon, 6 Jan 2020 01:20:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727309AbgAFBUh (ORCPT ); Sun, 5 Jan 2020 20:20:37 -0500 Received: from mga12.intel.com ([192.55.52.136]:63845 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727268AbgAFBUg (ORCPT ); Sun, 5 Jan 2020 20:20:36 -0500 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 05 Jan 2020 17:20:33 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,400,1571727600"; d="scan'208";a="253191050" Received: from richard.sh.intel.com (HELO localhost) ([10.239.159.54]) by fmsmga002.fm.intel.com with ESMTP; 05 Jan 2020 17:20:31 -0800 Date: Mon, 6 Jan 2020 09:20:34 +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: <20200106012034.GA15705@richard> Reply-To: Wei Yang References: <20200103143407.1089-1-richardw.yang@linux.intel.com> <20200103233925.GA3678@richard> 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) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 03, 2020 at 04:44:59PM -0800, David Rientjes wrote: >On Sat, 4 Jan 2020, Wei Yang wrote: > >> 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? >> > >I mean your patch is obviously correct :) It should likely also have a >stable@vger.kernel.org # 5.4+ Ah, my poor English ;-) > >Acked-by: David Rientjes -- Wei Yang Help you, Help me