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,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 2517CC2BB55 for ; Thu, 16 Apr 2020 11:20:55 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id BBB0821BE5 for ; Thu, 16 Apr 2020 11:20:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BBB0821BE5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=virtuozzo.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 393108E00A4; Thu, 16 Apr 2020 07:20:54 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 345C78E0001; Thu, 16 Apr 2020 07:20:54 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2A9788E00A4; Thu, 16 Apr 2020 07:20:54 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0144.hostedemail.com [216.40.44.144]) by kanga.kvack.org (Postfix) with ESMTP id 12C0B8E0001 for ; Thu, 16 Apr 2020 07:20:54 -0400 (EDT) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id D7778482A for ; Thu, 16 Apr 2020 11:20:53 +0000 (UTC) X-FDA: 76713475986.17.elbow70_7c9e62336a25 X-HE-Tag: elbow70_7c9e62336a25 X-Filterd-Recvd-Size: 2174 Received: from relay.sw.ru (relay.sw.ru [185.231.240.75]) by imf15.hostedemail.com (Postfix) with ESMTP for ; Thu, 16 Apr 2020 11:20:53 +0000 (UTC) Received: from [192.168.15.163] by relay.sw.ru with esmtp (Exim 4.92.3) (envelope-from ) id 1jP2ZF-0003vx-HH; Thu, 16 Apr 2020 14:20:25 +0300 Subject: Re: [PATCH v4] mm/ksm: Fix NULL pointer dereference when KSM zero page is enabled To: Markus Elfring , Andrew Morton , Muchun Song , Xiongchun Duan Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, David Hildenbrand , Yang Shi References: <20200416025034.29780-1-songmuchun@bytedance.com> <20200415195841.da4361916f662a0136a271a5@linux-foundation.org> <516df5d7-b514-11dc-130e-f1a2edce0108@web.de> From: Kirill Tkhai Message-ID: Date: Thu, 16 Apr 2020 14:20:24 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <516df5d7-b514-11dc-130e-f1a2edce0108@web.de> 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 16.04.2020 09:14, Markus Elfring wrote: > =E2=80=A6 >>> +++ b/mm/ksm.c >>> @@ -2112,8 +2112,15 @@ static void cmp_and_merge_page(struct page *pa= ge, struct rmap_item *rmap_item) > =E2=80=A6 >>> + if (vma) >>> + err =3D try_to_merge_one_page(vma, page, >>> + ZERO_PAGE(rmap_item->address)); >>> + else >>> + /** >>> + * If the vma is out of date, we do not need to >>> + * continue. >>> + */ >>> + err =3D 0; >>> up_read(&mm->mmap_sem); > =E2=80=A6 >> It's conventional to put braces around multi-line blocks such as this. >=20 > Are there different views to consider around the usage of single statem= ents > together with curly brackets in if branches? For me Andrew's conversion is the best readable. I try to comment the cod= e the same way myself. I even thought it's kernel default style :) Kirill