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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 06794C2BB55 for ; Thu, 16 Apr 2020 20:08:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D98AB21744 for ; Thu, 16 Apr 2020 20:08:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731014AbgDPUIN (ORCPT ); Thu, 16 Apr 2020 16:08:13 -0400 Received: from smtprelay0085.hostedemail.com ([216.40.44.85]:47790 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728776AbgDPUIK (ORCPT ); Thu, 16 Apr 2020 16:08:10 -0400 Received: from filter.hostedemail.com (clb03-v110.bra.tucows.net [216.40.38.60]) by smtprelay06.hostedemail.com (Postfix) with ESMTP id ECAD618224D93; Thu, 16 Apr 2020 20:08:08 +0000 (UTC) X-Session-Marker: 6A6F6540706572636865732E636F6D X-HE-Tag: alley89_6406c9b99173f X-Filterd-Recvd-Size: 2121 Received: from XPS-9350.home (unknown [47.151.136.130]) (Authenticated sender: joe@perches.com) by omf16.hostedemail.com (Postfix) with ESMTPA; Thu, 16 Apr 2020 20:08:07 +0000 (UTC) Message-ID: <4a40bfcf1c964bbb9b68a8b7c467a5a770907e4a.camel@perches.com> Subject: Re: [PATCH v4] mm/ksm: Fix NULL pointer dereference when KSM zero page is enabled From: Joe Perches To: Kirill Tkhai , Markus Elfring , Andrew Morton , Muchun Song , Xiongchun Duan Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, David Hildenbrand , Yang Shi Date: Thu, 16 Apr 2020 13:05:54 -0700 In-Reply-To: References: <20200416025034.29780-1-songmuchun@bytedance.com> <20200415195841.da4361916f662a0136a271a5@linux-foundation.org> <516df5d7-b514-11dc-130e-f1a2edce0108@web.de> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.34.1-2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2020-04-16 at 14:20 +0300, Kirill Tkhai wrote: > On 16.04.2020 09:14, Markus Elfring wrote: > > … > > > > +++ b/mm/ksm.c > > > > @@ -2112,8 +2112,15 @@ static void cmp_and_merge_page(struct page *page, struct rmap_item *rmap_item) > > … > > > > + if (vma) > > > > + err = 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. trivia: It's generally better to not use "/**" as that's used for kernel-doc and this could be a single line like + /* If the vma is out of date, no need to continue */ > > > It's conventional to put braces around multi-line blocks such as this. true > > Are there different views to consider around the usage of single statements > > together with curly brackets in if branches? no