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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8758FC433FE for ; Mon, 21 Mar 2022 09:26:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345867AbiCUJ1X (ORCPT ); Mon, 21 Mar 2022 05:27:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45582 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244434AbiCUJ1U (ORCPT ); Mon, 21 Mar 2022 05:27:20 -0400 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 264604F479 for ; Mon, 21 Mar 2022 02:25:55 -0700 (PDT) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.57]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4KMTdy4r50z9srY; Mon, 21 Mar 2022 17:21:58 +0800 (CST) Received: from [10.174.177.76] (10.174.177.76) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Mon, 21 Mar 2022 17:25:52 +0800 Subject: Re: [PATCH] mm/mempolicy: fix potential mpol_new leak in shared_policy_replace To: Michal Hocko CC: Andrew Morton , , , , References: <20220311093624.39546-1-linmiaohe@huawei.com> <26577566-ae1e-801c-8c64-89c2c89a487d@huawei.com> <24b2a9ef-eea0-09bd-6842-121d8436e56a@huawei.com> <6ebebfd6-6356-e956-4fbc-0abaa58308ff@huawei.com> <207bbd69-6678-5120-3760-e2bcd9803a14@huawei.com> <36b0ea44-39ab-bc52-1ae5-eca2cf832900@huawei.com> From: Miaohe Lin Message-ID: <0d306244-748e-9774-8578-525073770a3f@huawei.com> Date: Mon, 21 Mar 2022 17:25:51 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.76] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/3/21 16:59, Michal Hocko wrote: > On Sat 19-03-22 18:42:33, Miaohe Lin wrote: > [...] >> This would be triggered easily with below code snippet in my virtual machine: >> >> shmid = shmget((key_t)5566, 1024 * PAGE_SIZE, 0666|IPC_CREAT); >> shm = shmat(shmid, 0, 0); >> loop { >> mbind(shm, 1024 * PAGE_SIZE, MPOL_LOCAL, mask, maxnode, 0); >> mbind(shm + 128 * PAGE_SIZE, 128 * PAGE_SIZE, MPOL_DEFAULT, mask, maxnode, 0); >> } >> >> If there're many process doing the above work, mpol_new will be leaked easily. >> So should I resend this patch with Cc stable? But it seems I'am not supposed >> to make this decision and the maintainer will take care of this? > > I would just add > Fixes: 42288fe366c4 ("mm: mempolicy: Convert shared_policy mutex to spinlock") > Cc: stable # 3.8 > > And also add your above reproducer snippet added to the original changelog. > This would be more then enough to conclude the importance. Will do. Many thanks for your patience and suggestion! > > Thank you for working hard on this! Thanks. :) >