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Tue, 5 Mar 2024 14:57:08 +0800 Message-ID: <7e6f9061-1bb9-4d7d-b679-c0183037cbf2@huawei.com> Date: Tue, 5 Mar 2024 14:57:08 +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: [bug report] dead loop in generic_perform_write() //Re: [PATCH v7 07/12] iov_iter: Convert iterate*() to inline funcs To: Linus Torvalds , David Howells CC: Al Viro , Jens Axboe , Christoph Hellwig , Christian Brauner , David Laight , Matthew Wilcox , Jeff Layton , , , , , , Kefeng Wang References: <20230925120309.1731676-1-dhowells@redhat.com> <20230925120309.1731676-8-dhowells@redhat.com> <4e80924d-9c85-f13a-722a-6a5d2b1c225a@huawei.com> <769021.1709553367@warthog.procyon.org.uk> 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: dggems706-chm.china.huawei.com (10.3.19.183) To kwepemm600017.china.huawei.com (7.193.23.234) X-Rspam-User: X-Stat-Signature: awyyak36sd4i5ybwtnp4nemzuts5h7sp X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 93370140003 X-HE-Tag: 1709621834-533113 X-HE-Meta: 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 8ujBseLo nlFyWZg3bd4DIV5O5gUAUPBD6iNYH1Vn6OO6qHBaWdr8WnWU6owVkwobaeXASAC2yP0nhMKd8PtJL1ibGjXBS2n3Agu/WO4xOsyG6mcSjW/o737B/ikmlW8kMsJUmX5StPwek+d9sY1Xm3LJKy2hzjFt0j7ep3qc7PqgwRuIAMRxUB7Y0u5rmfQm6HJi5GlHkUZQLj+FKYkhyuwQ= 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: List-Subscribe: List-Unsubscribe: 在 2024/3/5 2:32, Linus Torvalds 写道: > On Mon, 4 Mar 2024 at 03:56, David Howells wrote: >> >> That said, I wonder if: >> >> #ifdef copy_mc_to_kernel >> >> should be: >> >> #ifdef CONFIG_ARCH_HAS_COPY_MC > > Hmm. Maybe. We do have that > > #ifdef copy_mc_to_kernel > > pattern already in , so clearly we've done it both ways. > > I personally like the "just test for the thing you are using" model, > which is then why I did it that way, but I don't have hugely strong > opinions on it. > >> and whether it's possible to find out dynamically if MCEs can occur at all. > > I really wanted to do something like that, and look at the source page > to decide "is this a pmem page that can cause machine checks", but I > didn't find any obvious way to do that. > > Improvement suggestions more than welcome. I used EINJ to simulate hardware memory error and tested it on an ARM64 server. This solution can solve the coredump deadloop problem. I'll sort it out and send the patch. Thanks, Tong. > > Linus > .