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 712FBC6FD1D for ; Thu, 30 Mar 2023 06:12:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230150AbjC3GME (ORCPT ); Thu, 30 Mar 2023 02:12:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38898 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229505AbjC3GMD (ORCPT ); Thu, 30 Mar 2023 02:12:03 -0400 Received: from out30-111.freemail.mail.aliyun.com (out30-111.freemail.mail.aliyun.com [115.124.30.111]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 672C565A8; Wed, 29 Mar 2023 23:11:52 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R181e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046051;MF=xueshuai@linux.alibaba.com;NM=1;PH=DS;RN=21;SR=0;TI=SMTPD_---0VezS-Oc_1680156705; Received: from 30.240.113.3(mailfrom:xueshuai@linux.alibaba.com fp:SMTPD_---0VezS-Oc_1680156705) by smtp.aliyun-inc.com; Thu, 30 Mar 2023 14:11:47 +0800 Message-ID: <0133c209-b098-e822-58d7-27568888c282@linux.alibaba.com> Date: Thu, 30 Mar 2023 14:11:45 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.9.0 Subject: Re: [PATCH v3 0/2] ACPI: APEI: handle synchronous exceptions with proper si_code Content-Language: en-US To: "Rafael J. Wysocki" , tony.luck@intel.com, james.morse@arm.com, bp@alien8.de, Naoya Horiguchi Cc: linux-acpi@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, justin.he@arm.com, akpm@linux-foundation.org, ardb@kernel.org, ashish.kalra@amd.com, baolin.wang@linux.alibaba.com, cuibixuan@linux.alibaba.com, dave.hansen@linux.intel.com, jarkko@kernel.org, lenb@kernel.org, linmiaohe@huawei.com, lvying6@huawei.com, xiexiuqi@huawei.com, zhuo.song@linux.alibaba.com References: <20221027042445.60108-1-xueshuai@linux.alibaba.com> <20230317072443.3189-1-xueshuai@linux.alibaba.com> From: Shuai Xue In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On 2023/3/21 AM2:03, Rafael J. Wysocki wrote: > On Fri, Mar 17, 2023 at 8:25 AM Shuai Xue wrote: >> >> changes since v2 by addressing comments from Naoya: >> - rename mce_task_work to sync_task_work >> - drop ACPI_HEST_NOTIFY_MCE case in is_hest_sync_notify() >> - add steps to reproduce this problem in cover letter >> - Link: https://lore.kernel.org/lkml/1aa0ca90-d44c-aa99-1e2d-bd2ae610b088@linux.alibaba.com/T/#mb3dede6b7a6d189dc8de3cf9310071e38a192f8e >> >> changes since v1: >> - synchronous events by notify type >> - Link: https://lore.kernel.org/lkml/20221206153354.92394-3-xueshuai@linux.alibaba.com/ >> >> Currently, both synchronous and asynchronous error are queued and handled >> by a dedicated kthread in workqueue. And Memory failure for synchronous >> error is synced by a cancel_work_sync trick which ensures that the >> corrupted page is unmapped and poisoned. And after returning to user-space, >> the task starts at current instruction which triggering a page fault in >> which kernel will send SIGBUS to current process due to VM_FAULT_HWPOISON. >> >> However, the memory failure recovery for hwpoison-aware mechanisms does not >> work as expected. For example, hwpoison-aware user-space processes like >> QEMU register their customized SIGBUS handler and enable early kill mode by >> seting PF_MCE_EARLY at initialization. Then the kernel will directy notify >> the process by sending a SIGBUS signal in memory failure with wrong >> si_code: BUS_MCEERR_AO si_code to the actual user-space process instead of >> BUS_MCEERR_AR. >> >> To address this problem: >> >> - PATCH 1 sets mf_flags as MF_ACTION_REQUIRED on synchronous events which >> indicates error happened in current execution context >> - PATCH 2 separates synchronous error handling into task work so that the >> current context in memory failure is exactly belongs to the task >> consuming poison data. >> >> Then, kernel will send SIGBUS with proper si_code in kill_proc(). >> >> Lv Ying and XiuQi also proposed to address similar problem and we discussed >> about new solution to add a new flag(acpi_hest_generic_data::flags bit 8) to >> distinguish synchronous event. [2][3] The UEFI community still has no response. >> After a deep dive into the SDEI TRM, the SDEI notification should be used for >> asynchronous error. As SDEI TRM[1] describes "the dispatcher can simulate an >> exception-like entry into the client, **with the client providing an additional >> asynchronous entry point similar to an interrupt entry point**". The client >> (kernel) lacks complete synchronous context, e.g. systeam register (ELR, ESR, >> etc). So notify type is enough to distinguish synchronous event. >> >> To reproduce this problem: >> >> # STEP1: enable early kill mode >> #sysctl -w vm.memory_failure_early_kill=1 >> vm.memory_failure_early_kill = 1 >> >> # STEP2: inject an UCE error and consume it to trigger a synchronous error >> #einj_mem_uc single >> 0: single vaddr = 0xffffb0d75400 paddr = 4092d55b400 >> injecting ... >> triggering ... >> signal 7 code 5 addr 0xffffb0d75000 >> page not present >> Test passed >> >> The si_code (code 5) from einj_mem_uc indicates that it is BUS_MCEERR_AO error >> and it is not fact. >> >> After this patch set: >> >> # STEP1: enable early kill mode >> #sysctl -w vm.memory_failure_early_kill=1 >> vm.memory_failure_early_kill = 1 >> >> # STEP2: inject an UCE error and consume it to trigger a synchronous error >> #einj_mem_uc single >> 0: single vaddr = 0xffffb0d75400 paddr = 4092d55b400 >> injecting ... >> triggering ... >> signal 7 code 4 addr 0xffffb0d75000 >> page not present >> Test passed >> >> The si_code (code 4) from einj_mem_uc indicates that it is BUS_MCEERR_AR error >> as we expected. >> >> [1] https://developer.arm.com/documentation/den0054/latest/ >> [2] https://lore.kernel.org/linux-arm-kernel/20221205160043.57465-4-xiexiuqi@huawei.com/T/ >> [3] https://lore.kernel.org/lkml/20221209095407.383211-1-lvying6@huawei.com/ >> >> Shuai Xue (2): >> ACPI: APEI: set memory failure flags as MF_ACTION_REQUIRED on >> synchronous events >> ACPI: APEI: handle synchronous exceptions in task work >> >> drivers/acpi/apei/ghes.c | 135 ++++++++++++++++++++++++--------------- >> include/acpi/ghes.h | 3 - >> mm/memory-failure.c | 13 ---- >> 3 files changed, 83 insertions(+), 68 deletions(-) >> >> -- > > I really need the designated APEI reviewers to give their feedback on this. Gentle ping. Best Regards. Shuai