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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 29F23C433EF for ; Mon, 25 Apr 2022 02:20:30 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5B54D6B009A; Sun, 24 Apr 2022 22:20:29 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 565236B009B; Sun, 24 Apr 2022 22:20:29 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 42CF76B009C; Sun, 24 Apr 2022 22:20:29 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.27]) by kanga.kvack.org (Postfix) with ESMTP id 31AC46B009A for ; Sun, 24 Apr 2022 22:20:29 -0400 (EDT) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id E86DE21E6F for ; Mon, 25 Apr 2022 02:20:28 +0000 (UTC) X-FDA: 79393797336.15.42046A5 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by imf09.hostedemail.com (Postfix) with ESMTP id 731C314002F for ; Mon, 25 Apr 2022 02:20:25 +0000 (UTC) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.53]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4KmpdB0qyQzhYgg; Mon, 25 Apr 2022 10:20:14 +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 15.1.2375.24; Mon, 25 Apr 2022 10:20:24 +0800 Subject: Re: [PATCH v3 1/3] mm/swapfile: unuse_pte can map random data if swap read fails To: =?UTF-8?B?SE9SSUdVQ0hJIE5BT1lBKOWggOWPoyDnm7TkuZ8p?= CC: "akpm@linux-foundation.org" , "willy@infradead.org" , "vbabka@suse.cz" , "dhowells@redhat.com" , "neilb@suse.de" , "david@redhat.com" , "apopple@nvidia.com" , "surenb@google.com" , "minchan@kernel.org" , "peterx@redhat.com" , "sfr@canb.auug.org.au" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" References: <20220424091105.48374-1-linmiaohe@huawei.com> <20220424091105.48374-2-linmiaohe@huawei.com> <20220425010804.GA3746096@hori.linux.bs1.fc.nec.co.jp> From: Miaohe Lin Message-ID: <159b4ea1-7f39-0486-8e2e-2843e1ebbe2a@huawei.com> Date: Mon, 25 Apr 2022 10:20:23 +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: <20220425010804.GA3746096@hori.linux.bs1.fc.nec.co.jp> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit 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 X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 731C314002F X-Stat-Signature: n5ezhdcyn9qg5h9t84ngoh1faitas4bo X-Rspam-User: Authentication-Results: imf09.hostedemail.com; dkim=none; spf=pass (imf09.hostedemail.com: domain of linmiaohe@huawei.com designates 45.249.212.187 as permitted sender) smtp.mailfrom=linmiaohe@huawei.com; dmarc=pass (policy=quarantine) header.from=huawei.com X-HE-Tag: 1650853225-528877 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 2022/4/25 9:08, HORIGUCHI NAOYA(堀口 直也) wrote: > On Sun, Apr 24, 2022 at 05:11:03PM +0800, Miaohe Lin wrote: >> There is a bug in unuse_pte(): when swap page happens to be unreadable, >> page filled with random data is mapped into user address space. In case >> of error, a special swap entry indicating swap read fails is set to the >> page table. So the swapcache page can be freed and the user won't end up >> with a permanently mounted swap because a sector is bad. And if the page >> is accessed later, the user process will be killed so that corrupted data >> is never consumed. On the other hand, if the page is never accessed, the >> user won't even notice it. >> >> Signed-off-by: Miaohe Lin >> Acked-by: David Hildenbrand > > Hi Miaohe, > > This bug sounds relatively serious to me, and it seems old, so is it worth > sending to -stable? This bug is really old but it's never seen yet because swapoff is supposed only to be done before rebooting the system. But swapoff can happen anytime. Poor guys might come across it and get wrong data. So I think it's worth sending to -stable. BTW: This patch should be revised in order to go to the stable version. Thanks! > > Thanks, > Naoya Horiguchi >