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=-2.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 D55E1C2BA2B for ; Thu, 16 Apr 2020 06:00:55 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 691582076A for ; Thu, 16 Apr 2020 06:00:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=web.de header.i=@web.de header.b="my+5VYU4" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 691582076A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=web.de Authentication-Results: mail.kernel.org; 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Thu, 16 Apr 2020 06:00:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=web.de; s=dbaedf251592; t=1587016846; bh=RpJs2DXqttTf+Vv+o/O3GhRJDxw7hx42291B9GNdEes=; h=X-UI-Sender-Class:Subject:To:Cc:References:From:Date:In-Reply-To; b=my+5VYU4nwFmi1ZgvGFQi+rfNBWfPVHRDiDh335R1vzjJLAyteol+ybjJ687+gh1s ar0N4iHlmyq+RWvnZMezK7mpCrvXAiFYCSC4F2nwbsgbVLUQQsCJUNYksvbNktsVta AsksgwJV8rsXu0YIW0q5O+EL7KbmdFfCzRIUf9Ms= X-UI-Sender-Class: c548c8c5-30a9-4db5-a2e7-cb6cb037b8f9 Received: from [192.168.1.3] ([2.243.109.113]) by smtp.web.de (mrweb103 [213.165.67.124]) with ESMTPSA (Nemesis) id 0M6mTI-1j1dL00G2O-00wUpS; Thu, 16 Apr 2020 08:00:46 +0200 Subject: Re: [PATCH v4] mm/ksm: Fix NULL pointer dereference when KSM zero page is enabled To: Muchun Song , Xiongchun Duan , linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Andrew Morton , David Hildenbrand , Kirill Tkhai , Yang Shi References: <20200416025034.29780-1-songmuchun@bytedance.com> From: Markus Elfring Autocrypt: addr=Markus.Elfring@web.de; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200416025034.29780-1-songmuchun@bytedance.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:RKx8zEDYvDQfBB2YiAv7zoArG3Sm2dAqndOJZdX62p3epEf9Q6u twj9rG3Y6d39g0Yw2AVdB65UoR7CVz5k3UWZq+ltssKebCliXGK7+v1iclJB5hb7IzW+vXU iPEy/bHOeOEPg8mE5ZI3ajqM0E/5QJ3sK+88iIg+cHHmSmtcsDNGPZMGnJGZtRrVd1kSzS6 rfPEFBwLZQqgqO2vbmT/w== X-UI-Out-Filterresults: notjunk:1;V03:K0:5dIKY8+DE64=:csTGDJ/L22B1g1+uiYI1sF WAZQEr5oOIKpZ5hdkENcqnSTX6kO8Ib562pVL6KA3VYkvSQOZaBaO2GcBDSJNf6ufm4ob1jQ5 /H6oCw5Uviu46yeO+sbltJC8Xdx+FfWe9SV+efuGYFRnMmroqiqfMC5GPI9CtUZJCzJSt/2bE xv5IfRoSkwaZKT/jhIEt7VqekWHC0GlTR+yiTK0MC8TrynC56Ea9MNi+lYdgR4wJY8qRheTvz CPunCqgocfOO0uzTQxekImHUkxJFtIkHb//9lBzSa0R0jydR2mdgUoZmPU3nNLJGGEFserXqH F0nL8y4DiOY/pkzG3OcnE/73y1Xb2WguibyNLpOlH8L04xSj001UrJxi0VPpSF6mcmnBDjVb6 bKyTEJBPNRGxWC6XYu1hocNL72tCsfEk+Roa4DbL0VSbMKcYYkBe416mqUstwZPKRWWYZK+dC iuLxvaKaJlbGhcqy17HHKe5xRTujvp6dqh+Yh6zzOrTH4n9lgno8O2hqOxnjGBYd711SyVxBY yhSsMc55qw2UIiS3puVT1UD63u4Rkp7d4EFvqIQnL4VhD4lvsMiS0/yGVgRmi4Ne2yVMNaPAj H0fZ9V/SJP5qmhx+4Xy37Dt2i/e4AM5Bp1yEujjvUTlQTE+1qHuuN7paG/DMsNI8CwTtkDbKc eK1zc2CHUlHE59U29pCzd/pDSXch6h3Jj2LcHwHYYLDH/KISJqNM5deg+mHes9mghAS05xAbb gkJKWO7rizTZ4MQH6kITYnBqMXNbEDIrlIMsxuabPhGmL+qGUeNgVo4gaL9khWyDuONu1zBFg F21P2OT23gCd6T/SeCiURX51jhmuLLBzE2Vw5Fq2W0F18QqDi1XOI2FrnTWU/Qj6hdiDoNHNt jOCxydcywMSZ9SCcTCoiB9WJQo2cAj/q0lM6jLsozsL+2Q3wcfvk4Rby5G2dvnt2YAQKRWuQW qs8IfNRt6AE3QcT/+nvQmfJJvoWY5EnlN5CIiySFmBUT8WJu3IncRwIvL4PJSQaYPIGf+76R6 PTdJmmuTHR+AfG4SCTjUj46qc4QPGpYV3dC90RXcQNexCz8piu+KGUzPb4Go+rNovY3FyvjL2 dMMHhuRsFd6aTo2zIgF/dpjmkinCFBEySkADoAS6F2ebzpU4iF29W+HhKDSqTYJyaoz8RAk2u 0JZ29gs4utsozceN1W47SrVk5X6usP4ZeiEQasnh1gAj/6gIDXqKvZv1qGuyuRe/huMlc1qOU eXdxGCtXIY9vY4BVA X-Bogosity: Ham, tests=bogofilter, spamicity=0.017329, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: > to a crash when we access vm_mm(its offset is 0x40) later in Would the text variant =E2=80=9C=E2=80=A6 vm_mm (its =E2=80=A6=E2=80=9D be= a bit nicer? =E2=80=A6 > +++ b/mm/ksm.c > @@ -2112,8 +2112,15 @@ static void cmp_and_merge_page(struct page *page,= struct rmap_item *rmap_item) =E2=80=A6 > + if (vma) > + err =3D try_to_merge_one_page(vma, page, > + ZERO_PAGE(rmap_item->address)); Can the parameter alignment trigger further software development considera= tions for such a function call? Regards, Markus