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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C5CCCC021A0 for ; Fri, 14 Feb 2025 01:46:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:CC:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=s6gybk0sDxsKPqVranOYHJNAYoMVjrehj07uCNXs5vM=; b=ny6qyJziv7StqP9RLU//VUfPZE A5QOTnYmTa2ttN/Ym0ac4xCQ/H6TXvTAnBbetOBu882y/4tCxcWqSMqj5ypsnw2NPdiwv5Gamj8Td OTgz1SSDoUY2LP3sULmJlYvT+str2U10xMRnl74oDqAA+F+2AHzcJbTrxuYUmIis8P4zaV9wLIxWV QLHbRcxgh2vKMSHIZZSFxGOCesNEorh5JVyqvPUdHr+PUjvtvKRW+asWTOkYKbZwn7WDJgUOBmqwU XOE1i2ZlRVstpq+sUWDLX7K0Jjtcal8AFMd5rRqC3uGzip/NZT60BO1cN8a7HZrh3ghLhbDXvTqPq TsXIldqA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tikm9-0000000DDdt-0TA5; Fri, 14 Feb 2025 01:45:53 +0000 Received: from szxga01-in.huawei.com ([45.249.212.187]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tikkg-0000000DDUr-1XG1 for linux-arm-kernel@lists.infradead.org; Fri, 14 Feb 2025 01:44:24 +0000 Received: from mail.maildlp.com (unknown [172.19.163.252]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4YvF8m1vkrz11PdJ; Fri, 14 Feb 2025 09:39:36 +0800 (CST) Received: from kwepemk500005.china.huawei.com (unknown [7.202.194.90]) by mail.maildlp.com (Postfix) with ESMTPS id 9BD7F1800EA; Fri, 14 Feb 2025 09:44:05 +0800 (CST) Received: from [10.174.179.234] (10.174.179.234) by kwepemk500005.china.huawei.com (7.202.194.90) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Fri, 14 Feb 2025 09:44:03 +0800 Message-ID: Date: Fri, 14 Feb 2025 09:44:02 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH v13 2/5] arm64: add support for ARCH_HAS_COPY_MC To: Catalin Marinas CC: Mark Rutland , Jonathan Cameron , Mauro Carvalho Chehab , Will Deacon , Andrew Morton , James Morse , Robin Murphy , Andrey Konovalov , Dmitry Vyukov , Vincenzo Frascino , Michael Ellerman , Nicholas Piggin , Andrey Ryabinin , Alexander Potapenko , Christophe Leroy , Aneesh Kumar K.V , "Naveen N. Rao" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , , "H. Peter Anvin" , Madhavan Srinivasan , , , , , , , Guohanjun References: <20241209024257.3618492-1-tongtiangen@huawei.com> <20241209024257.3618492-3-tongtiangen@huawei.com> From: Tong Tiangen In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.179.234] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To kwepemk500005.china.huawei.com (7.202.194.90) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250213_174422_769745_F0A06B57 X-CRM114-Status: GOOD ( 18.87 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 在 2025/2/13 0:21, Catalin Marinas 写道: > (catching up with old threads) > > On Mon, Dec 09, 2024 at 10:42:54AM +0800, Tong Tiangen wrote: >> For the arm64 kernel, when it processes hardware memory errors for >> synchronize notifications(do_sea()), if the errors is consumed within the >> kernel, the current processing is panic. However, it is not optimal. >> >> Take copy_from/to_user for example, If ld* triggers a memory error, even in >> kernel mode, only the associated process is affected. Killing the user >> process and isolating the corrupt page is a better choice. > > I agree that killing the user process and isolating the page is a better > choice but I don't see how the latter happens after this patch. Which > page would be isolated? The SEA is triggered when the page with hardware error is read. After that, the page is isolated in memory_failure() (mf). The processing of mf is mentioned in the comments of do_sea(). /* * APEI claimed this as a firmware-first notification. * Some processing deferred to task_work before ret_to_user(). */ Some processing include mf. > >> Add new fixup type EX_TYPE_KACCESS_ERR_ZERO_MEM_ERR to identify insn >> that can recover from memory errors triggered by access to kernel memory, >> and this fixup type is used in __arch_copy_to_user(), This make the regular >> copy_to_user() will handle kernel memory errors. > > Is the assumption that the error on accessing kernel memory is > transient? There's no way to isolate the kernel page and also no point > in isolating the destination page either. Yes, it's transient, the kernel page in mf can't be isolated, the transient access (ld) of this kernel page is currently expected to kill the user-mode process to avoid error spread. The SEA processes synchronization errors. Only hardware errors on the source page can be detected (Through synchronous ld insn) and processed. The destination page cannot be processed. >