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=ham 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 5632EC00523 for ; Mon, 6 Jan 2020 01:20:38 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E5D382072C for ; Mon, 6 Jan 2020 01:20:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E5D382072C 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 4CAF98E0005; Sun, 5 Jan 2020 20:20:37 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 47BE68E0003; Sun, 5 Jan 2020 20:20:37 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3913B8E0005; Sun, 5 Jan 2020 20:20:37 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0051.hostedemail.com [216.40.44.51]) by kanga.kvack.org (Postfix) with ESMTP id 24ED68E0003 for ; Sun, 5 Jan 2020 20:20:37 -0500 (EST) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id CEC0A181AEF07 for ; Mon, 6 Jan 2020 01:20:36 +0000 (UTC) X-FDA: 76345454472.27.view89_5c979116c7c4c X-HE-Tag: view89_5c979116c7c4c X-Filterd-Recvd-Size: 2948 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by imf18.hostedemail.com (Postfix) with ESMTP for ; Mon, 6 Jan 2020 01:20:36 +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 orsmga103.jf.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) 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 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