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=-4.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,HK_RANDOM_FROM,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 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 C23C4C433B4 for ; Fri, 9 Apr 2021 06:49:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8459B610C8 for ; Fri, 9 Apr 2021 06:49:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233373AbhDIGth (ORCPT ); Fri, 9 Apr 2021 02:49:37 -0400 Received: from mail.kingsoft.com ([114.255.44.146]:53780 "EHLO mail.kingsoft.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S231540AbhDIGt2 (ORCPT ); Fri, 9 Apr 2021 02:49:28 -0400 X-AuditID: 0a580157-4f324a80000551c1-3a-606ff8e6ca10 Received: from mail.kingsoft.com (localhost [10.88.1.79]) (using TLS with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client did not present a certificate) by mail.kingsoft.com (SMG-1-NODE-87) with SMTP id EA.2C.20929.6E8FF606; Fri, 9 Apr 2021 14:49:10 +0800 (HKT) Received: from alex-virtual-machine (172.16.253.254) by KSBJMAIL4.kingsoft.cn (10.88.1.79) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Fri, 9 Apr 2021 14:49:10 +0800 Date: Fri, 9 Apr 2021 14:49:09 +0800 From: Aili Yao To: "Luck, Tony" CC: Borislav Petkov , "x86@kernel.org" , "linux-mm@kvack.org" , Andy Lutomirski , "HORIGUCHI NAOYA( =?UTF-8?B?5aCA5Y+j44CA55u05Lmf?=)" , Subject: Re: [RFC 0/4] Fix machine check recovery for copy_from_user Message-ID: <20210409144909.3488db39@alex-virtual-machine> In-Reply-To: <595ed0ac4fbb470ca9cfd256aaf1810e@intel.com> References: <20210326000235.370514-1-tony.luck@intel.com> <20210408101335.28fd3692@alex-virtual-machine> <595ed0ac4fbb470ca9cfd256aaf1810e@intel.com> Organization: kingsoft X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.30; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [172.16.253.254] X-ClientProxiedBy: KSBJMAIL1.kingsoft.cn (10.88.1.31) To KSBJMAIL4.kingsoft.cn (10.88.1.79) X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrHLMWRmVeSWpSXmKPExsXCFcHor/vsR36Cwf7FGhaXd81hc2D0+LxJ LoAxissmJTUnsyy1SN8ugSuj7/dStoK5HBUHd0k1MO5g62Lk5JAQMJF4seUWSxcjF4eQwHQm iZ3/ljFCOC8ZJc78ucXaxcjBwSKgIrHjGQtIA5uAqsSue7NYQWwRATWJS4sfMIPUMws0Mkkc +vwULCEs4CLxoWku2AZeASuJm6tuMIHYnAKWEk+XdIDVCAnMZJRYcFQExOYXEJPovfKfCWSX hIC9xOP1ihCtghInZz4B28ssoCNxYtUxZghbXmL72znMEGMUJQ4v+cUO8YySxJHuGVCPxUo0 HbjFNoFReBaSUbOQjJqFZNQCRuZVjCzFuemGmxghQRq+g3Fe00e9Q4xMHIyHGCU4mJVEeJub 8xOEeFMSK6tSi/Lji0pzUosPMUpzsCiJ8y7+kpcgJJCeWJKanZpakFoEk2Xi4JRqYCp6UV5y e+HSLR6xCiJL9p3weMaWKbrcY8oPsdZryjICPer61y/XGq7hXJi1qdklZoqb43XBqLOZfIfn R6zRnh28MbV4yypObs0lMfeWNa64NmHanS+qzetv7glw1wn9UqIpwO5xtH/nTBX+Nwf1vPbt j371Pm3+DDGjrXv2+O15K3U6963H1QWspzb2/79YPd8kOKD8bnNRQs6M7f7FLFvC813FHJs/ TFbR0LxtIWQZv7p7/2KGLWH9Ne5le4S115ZK9CvF35BxvB5q+zvso80VX967Nac1dif6mr/k qf/6+NyWBXUHO8UXnZZ3dDO24GuqaK8se7Uxy6FgGbeYwrIPRU2mBqfcFR8t2/GzXImlOCPR UIu5qDgRAIidVQfBAgAA Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 8 Apr 2021 14:39:09 +0000 "Luck, Tony" wrote: > > I have one scenario, may you take into account: > > > > If one copyin case occurs, write() returned by your patch, the user process may > > check the return values, for errors, it may exit the process, then the error page > > will be freed, and then the page maybe alloced to other process or to kernel itself, > > then code will initialize it and this will trigger one SRAO, if it's used by kernel, > > we may do nothing for this, and kernel may still touch it, and lead to one panic. > > In this case kill_me_never() calls memory_failure() with flags == 0. I think (hope!) > that means that it will unmap the page from the task, but will not send a signal. > > When the task exits the PTE for this page has the swap/poison signature, so the > page is not freed for re-use. > > -Tony Oh, Yes, Sorry for my rudeness and error-understandings, I just happen to can't control my emotions and get confused for some other things. Thanks! Aili Yao