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[23.128.96.18]) by mx.google.com with ESMTP id q4si11175034eji.14.2020.04.15.23.04.48; Wed, 15 Apr 2020 23:05:13 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@web.de header.s=dbaedf251592 header.b=my+5VYU4; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2407389AbgDPGBF (ORCPT + 99 others); Thu, 16 Apr 2020 02:01:05 -0400 Received: from mout.web.de ([212.227.17.12]:42335 "EHLO mout.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2407345AbgDPGA7 (ORCPT ); Thu, 16 Apr 2020 02:00:59 -0400 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; prefer-encrypt=mutual; keydata= mQINBFg2+xABEADBJW2hoUoFXVFWTeKbqqif8VjszdMkriilx90WB5c0ddWQX14h6w5bT/A8 +v43YoGpDNyhgA0w9CEhuwfZrE91GocMtjLO67TAc2i2nxMc/FJRDI0OemO4VJ9RwID6ltwt mpVJgXGKkNJ1ey+QOXouzlErVvE2fRh+KXXN1Q7fSmTJlAW9XJYHS3BDHb0uRpymRSX3O+E2 lA87C7R8qAigPDZi6Z7UmwIA83ZMKXQ5stA0lhPyYgQcM7fh7V4ZYhnR0I5/qkUoxKpqaYLp YHBczVP+Zx/zHOM0KQphOMbU7X3c1pmMruoe6ti9uZzqZSLsF+NKXFEPBS665tQr66HJvZvY GMDlntZFAZ6xQvCC1r3MGoxEC1tuEa24vPCC9RZ9wk2sY5Csbva0WwYv3WKRZZBv8eIhGMxs rcpeGShRFyZ/0BYO53wZAPV1pEhGLLxd8eLN/nEWjJE0ejakPC1H/mt5F+yQBJAzz9JzbToU 5jKLu0SugNI18MspJut8AiA1M44CIWrNHXvWsQ+nnBKHDHHYZu7MoXlOmB32ndsfPthR3GSv jN7YD4Ad724H8fhRijmC1+RpuSce7w2JLj5cYj4MlccmNb8YUxsE8brY2WkXQYS8Ivse39MX BE66MQN0r5DQ6oqgoJ4gHIVBUv/ZwgcmUNS5gQkNCFA0dWXznQARAQABtCZNYXJrdXMgRWxm cmluZyA8TWFya3VzLkVsZnJpbmdAd2ViLmRlPokCVAQTAQgAPhYhBHDP0hzibeXjwQ/ITuU9 Figxg9azBQJYNvsQAhsjBQkJZgGABQsJCAcCBhUICQoLAgQWAgMBAh4BAheAAAoJEOU9Figx g9azcyMP/iVihZkZ4VyH3/wlV3nRiXvSreqg+pGPI3c8J6DjP9zvz7QHN35zWM++1yNek7Ar OVXwuKBo18ASlYzZPTFJZwQQdkZSV+atwIzG3US50ZZ4p7VyUuDuQQVVqFlaf6qZOkwHSnk+ CeGxlDz1POSHY17VbJG2CzPuqMfgBtqIU1dODFLpFq4oIAwEOG6fxRa59qbsTLXxyw+PzRaR LIjVOit28raM83Efk07JKow8URb4u1n7k9RGAcnsM5/WMLRbDYjWTx0lJ2WO9zYwPgRykhn2 sOyJVXk9xVESGTwEPbTtfHM+4x0n0gC6GzfTMvwvZ9G6xoM0S4/+lgbaaa9t5tT/PrsvJiob kfqDrPbmSwr2G5mHnSM9M7B+w8odjmQFOwAjfcxoVIHxC4Cl/GAAKsX3KNKTspCHR0Yag78w i8duH/eEd4tB8twcqCi3aCgWoIrhjNS0myusmuA89kAWFFW5z26qNCOefovCx8drdMXQfMYv g5lRk821ZCNBosfRUvcMXoY6lTwHLIDrEfkJQtjxfdTlWQdwr0mM5ye7vd83AManSQwutgpI q+wE8CNY2VN9xAlE7OhcmWXlnAw3MJLW863SXdGlnkA3N+U4BoKQSIToGuXARQ14IMNvfeKX NphLPpUUnUNdfxAHu/S3tPTc/E/oePbHo794dnEm57LuuQINBFg2+xABEADZg/T+4o5qj4cw nd0G5pFy7ACxk28mSrLuva9tyzqPgRZ2bdPiwNXJUvBg1es2u81urekeUvGvnERB/TKekp25 4wU3I2lEhIXj5NVdLc6eU5czZQs4YEZbu1U5iqhhZmKhlLrhLlZv2whLOXRlLwi4jAzXIZAu 76mT813jbczl2dwxFxcT8XRzk9+dwzNTdOg75683uinMgskiiul+dzd6sumdOhRZR7YBT+xC wzfykOgBKnzfFscMwKR0iuHNB+VdEnZw80XGZi4N1ku81DHxmo2HG3icg7CwO1ih2jx8ik0r riIyMhJrTXgR1hF6kQnX7p2mXe6K0s8tQFK0ZZmYpZuGYYsV05OvU8yqrRVL/GYvy4Xgplm3 DuMuC7/A9/BfmxZVEPAS1gW6QQ8vSO4zf60zREKoSNYeiv+tURM2KOEj8tCMZN3k3sNASfoG fMvTvOjT0yzMbJsI1jwLwy5uA2JVdSLoWzBD8awZ2X/eCU9YDZeGuWmxzIHvkuMj8FfX8cK/ 2m437UA877eqmcgiEy/3B7XeHUipOL83gjfq4ETzVmxVswkVvZvR6j2blQVr+MhCZPq83Ota xNB7QptPxJuNRZ49gtT6uQkyGI+2daXqkj/Mot5tKxNKtM1Vbr/3b+AEMA7qLz7QjhgGJcie qp4b0gELjY1Oe9dBAXMiDwARAQABiQI8BBgBCAAmFiEEcM/SHOJt5ePBD8hO5T0WKDGD1rMF Alg2+xACGwwFCQlmAYAACgkQ5T0WKDGD1rOYSw/+P6fYSZjTJDAl9XNfXRjRRyJSfaw6N1pA Ahuu0MIa3djFRuFCrAHUaaFZf5V2iW5xhGnrhDwE1Ksf7tlstSne/G0a+Ef7vhUyeTn6U/0m +/BrsCsBUXhqeNuraGUtaleatQijXfuemUwgB+mE3B0SobE601XLo6MYIhPh8MG32MKO5kOY hB5jzyor7WoN3ETVNQoGgMzPVWIRElwpcXr+yGoTLAOpG7nkAUBBj9n9TPpSdt/npfok9ZfL /Q+ranrxb2Cy4tvOPxeVfR58XveX85ICrW9VHPVq9sJf/a24bMm6+qEg1V/G7u/AM3fM8U2m tdrTqOrfxklZ7beppGKzC1/WLrcr072vrdiN0icyOHQlfWmaPv0pUnW3AwtiMYngT96BevfA qlwaymjPTvH+cTXScnbydfOQW8220JQwykUe+sHRZfAF5TS2YCkQvsyf7vIpSqo/ttDk4+xc Z/wsLiWTgKlih2QYULvW61XU+mWsK8+ZlYUrRMpkauN4CJ5yTpvp+Orcz5KixHQmc5tbkLWf x0n1QFc1xxJhbzN+r9djSGGN/5IBDfUqSANC8cWzHpWaHmSuU3JSAMB/N+yQjIad2ztTckZY pwT6oxng29LzZspTYUEzMz3wK2jQHw+U66qBFk8whA7B2uAU1QdGyPgahLYSOa4XAEGb6wbI FEE= Message-ID: <039d201a-a5fc-5ce2-54a1-f236531f9829@web.de> Date: Thu, 16 Apr 2020 08:00:36 +0200 User-Agent: Mozilla/5.0 (X11; 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-Spam-Flag: NO 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 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > 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