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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 224FBC2D0DB for ; Wed, 29 Jan 2020 13:09:53 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id BDF8B20678 for ; Wed, 29 Jan 2020 13:09:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BDF8B20678 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=i-love.sakura.ne.jp Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 2E1E76B0005; Wed, 29 Jan 2020 08:09:52 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 290F26B0006; Wed, 29 Jan 2020 08:09:52 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1808E6B0007; Wed, 29 Jan 2020 08:09:52 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0018.hostedemail.com [216.40.44.18]) by kanga.kvack.org (Postfix) with ESMTP id 0358D6B0005 for ; Wed, 29 Jan 2020 08:09:51 -0500 (EST) Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id BC60A8249980 for ; Wed, 29 Jan 2020 13:09:51 +0000 (UTC) X-FDA: 76430704182.15.cup35_38ea97d9d455c X-HE-Tag: cup35_38ea97d9d455c X-Filterd-Recvd-Size: 2539 Received: from www262.sakura.ne.jp (www262.sakura.ne.jp [202.181.97.72]) by imf42.hostedemail.com (Postfix) with ESMTP for ; Wed, 29 Jan 2020 13:09:50 +0000 (UTC) Received: from fsav305.sakura.ne.jp (fsav305.sakura.ne.jp [153.120.85.136]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id 00TD9egE058776; Wed, 29 Jan 2020 22:09:40 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav305.sakura.ne.jp (F-Secure/fsigk_smtp/550/fsav305.sakura.ne.jp); Wed, 29 Jan 2020 22:09:40 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/fsav305.sakura.ne.jp) Received: from [192.168.1.9] (softbank126040062084.bbtec.net [126.40.62.84]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id 00TD9YDV058726 (version=TLSv1.2 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Wed, 29 Jan 2020 22:09:40 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Subject: Re: [PATCH] mm/page_counter: fix various data races To: Qian Cai Cc: Dmitry Vyukov , Michal Hocko , akpm@linux-foundation.org, hannes@cmpxchg.org, elver@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <59f892d0-5fc4-ae32-ce65-5a688d9180c8@I-love.SAKURA.ne.jp> <2D795DB7-66FE-4F01-872F-F8ACAE9505EF@lca.pw> From: Tetsuo Handa Message-ID: Date: Wed, 29 Jan 2020 22:09:29 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.4.2 MIME-Version: 1.0 In-Reply-To: <2D795DB7-66FE-4F01-872F-F8ACAE9505EF@lca.pw> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable 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 2020/01/29 21:25, Qian Cai wrote: >=20 >=20 >> On Jan 29, 2020, at 7:13 AM, Tetsuo Handa wrote: >> >> By the way, can READ_ONCE()/WRITE_ONCE() really solve this warning? >> The link above says read/write on the same location ( mm/page_counter.= c:129 ). >> I don't know how READ_ONCE()/WRITE_ONCE() can solve the race. >=20 > That looks like a different one where it complains about c->failcnt++. = I=E2=80=99ll send a separate patch for that. >=20 Ah, then this patch is meant for mm/page_counter.c:138 versus page_counte= r.c:139 race which was closed as invalid at https://syzkaller.appspot.com/bug?id=3D871391ec08074= 6185a2dd437c54d75fcd1ef0ef8 .