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 79AE9C7EE29 for ; Fri, 26 May 2023 01:57:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235743AbjEZB5r (ORCPT ); Thu, 25 May 2023 21:57:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42730 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229646AbjEZB5p (ORCPT ); Thu, 25 May 2023 21:57:45 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 98789E7; Thu, 25 May 2023 18:57:43 -0700 (PDT) Received: from dggpemm500001.china.huawei.com (unknown [172.30.72.56]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4QS7H93JvJzqSSc; Fri, 26 May 2023 09:53:09 +0800 (CST) Received: from [10.174.177.243] (10.174.177.243) by dggpemm500001.china.huawei.com (7.185.36.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.23; Fri, 26 May 2023 09:57:41 +0800 Message-ID: <76b50214-fcf8-37fe-47c9-cfcaf7517048@huawei.com> Date: Fri, 26 May 2023 09:57:40 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.10.1 Subject: Re: [PATCH] x86/mce: set MCE_IN_KERNEL_COPYIN for all MC-Safe Copy Content-Language: en-US To: Dave Hansen , Tony Luck , Borislav Petkov , Naoya Horiguchi CC: Thomas Gleixner , Ingo Molnar , Dave Hansen , , Andrew Morton , , , , References: <20230508022233.13890-1-wangkefeng.wang@huawei.com> <5570c23a-3b12-6685-cb0b-29fc1d58f541@intel.com> From: Kefeng Wang In-Reply-To: <5570c23a-3b12-6685-cb0b-29fc1d58f541@intel.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemm500001.china.huawei.com (7.185.36.107) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2023/5/26 1:18, Dave Hansen wrote: > On 5/7/23 19:22, Kefeng Wang wrote: >> Both EX_TYPE_FAULT_MCE_SAFE and EX_TYPE_DEFAULT_MCE_SAFE exception >> fixup types are used to identify fixups which allow in kernel #MC >> recovery, that is the Machine Check Safe Copy. >> >> For now, the MCE_IN_KERNEL_COPYIN flag is only set for EX_TYPE_COPY >> and EX_TYPE_UACCESS when copy from user, and corrupted page is >> isolated in this case, for MC-safe copy, memory_failure() is not >> always called, some places, like __wp_page_copy_user, copy_subpage, >> copy_user_gigantic_page and ksm_might_need_to_copy manually call >> memory_failure_queue() to cope with such unhandled error pages, >> recently coredump hwposion recovery support[1] is asked to do the >> same thing, and there are some other already existed MC-safe copy >> scenarios, eg, nvdimm, dm-writecache, dax, which has similar issue. > > That has to set some kind of record for run-on sentences. Could you > please try to rewrite this coherently? > >> The best way to fix them is set MCE_IN_KERNEL_COPYIN to MCE_SAFE >> exception, then kill_me_never() will be queued to call memory_failure() >> in do_machine_check() to isolate corrupted page, which avoid calling >> memory_failure_queue() after every MC-safe copy return. > > Could you try to send a v2 of this with a clear problem statement? > :( will try to make it more clear. > What is the end user visible effect of the problem and of your solution? The corrupted page won't be isolated for MC-safe copy scenario, and it could be accessed again by use application.