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 73B85C433EF for ; Wed, 25 May 2022 08:31:10 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 064438D0002; Wed, 25 May 2022 04:31:10 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id F32338D0001; Wed, 25 May 2022 04:31:09 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E1F9C8D0002; Wed, 25 May 2022 04:31:09 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id D4CC68D0001 for ; Wed, 25 May 2022 04:31:09 -0400 (EDT) Received: from smtpin21.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay12.hostedemail.com (Postfix) with ESMTP id BBB07120EAC for ; Wed, 25 May 2022 08:31:09 +0000 (UTC) X-FDA: 79503595458.21.1D8BDE8 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf08.hostedemail.com (Postfix) with ESMTP id 9A149160031 for ; Wed, 25 May 2022 08:30:47 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 24AEB1FB; Wed, 25 May 2022 01:31:08 -0700 (PDT) Received: from FVFF77S0Q05N (unknown [10.57.0.228]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id F3E743F73D; Wed, 25 May 2022 01:31:02 -0700 (PDT) Date: Wed, 25 May 2022 09:30:55 +0100 From: Mark Rutland To: Tong Tiangen Cc: James Morse , Andrew Morton , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Robin Murphy , Dave Hansen , Catalin Marinas , Will Deacon , Alexander Viro , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , x86@kernel.org, "H . Peter Anvin" , linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Kefeng Wang , Xie XiuQi , Guohanjun Subject: Re: [PATCH -next v4 3/7] arm64: add support for machine check error safe Message-ID: References: <20220420030418.3189040-1-tongtiangen@huawei.com> <20220420030418.3189040-4-tongtiangen@huawei.com> <46e5954c-a9a8-f4a8-07cc-de42e2753051@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <46e5954c-a9a8-f4a8-07cc-de42e2753051@huawei.com> X-Rspamd-Queue-Id: 9A149160031 X-Stat-Signature: zgski3ayueoichjntoqh5krqemxkupud Authentication-Results: imf08.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf08.hostedemail.com: domain of mark.rutland@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=mark.rutland@arm.com X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1653467447-527323 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 Thu, May 19, 2022 at 02:29:54PM +0800, Tong Tiangen wrote: > > > 在 2022/5/13 23:26, Mark Rutland 写道: > > On Wed, Apr 20, 2022 at 03:04:14AM +0000, Tong Tiangen wrote: > > > During the processing of arm64 kernel hardware memory errors(do_sea()), if > > > the errors is consumed in the kernel, the current processing is panic. > > > However, it is not optimal. > > > > > > Take uaccess for example, if the uaccess operation fails due to memory > > > error, only the user process will be affected, kill the user process > > > and isolate the user page with hardware memory errors is a better choice. > > > > Conceptually, I'm fine with the idea of constraining what we do for a > > true uaccess, but I don't like the implementation of this at all, and I > > think we first need to clean up the arm64 extable usage to clearly > > distinguish a uaccess from another access. > > OK,using EX_TYPE_UACCESS and this extable type could be recover, this is > more reasonable. Great. > For EX_TYPE_UACCESS_ERR_ZERO, today we use it for kernel accesses in a > couple of cases, such as > get_user/futex/__user_cache_maint()/__user_swpX_asm(), Those are all user accesses. However, __get_kernel_nofault() and __put_kernel_nofault() use EX_TYPE_UACCESS_ERR_ZERO by way of __{get,put}_mem_asm(), so we'd need to refactor that code to split the user/kernel cases higher up the callchain. > your suggestion is: > get_user continues to use EX_TYPE_UACCESS_ERR_ZERO and the other cases use > new type EX_TYPE_FIXUP_ERR_ZERO? Yes, that's the rough shape. We could make the latter EX_TYPE_KACCESS_ERR_ZERO to be clearly analogous to EX_TYPE_UACCESS_ERR_ZERO, and with that I susepct we could remove EX_TYPE_FIXUP. Thanks, Mark.