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Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.5.1 Subject: Re: [PATCH v2] mm: hwpoison: coredump: support recovery from dump_user_range() Content-Language: en-US To: "Luck, Tony" , =?UTF-8?B?SE9SSUdVQ0hJIE5BT1lBKOWggOWPoyDnm7TkuZ8p?= CC: "chu, jane" , Thomas Gleixner , Alexander Viro , Christian Brauner , "linux-fsdevel@vger.kernel.org" , "linux-mm@kvack.org" , Andrew Morton , Miaohe Lin , "linux-kernel@vger.kernel.org" , Tong Tiangen , Jens Axboe References: <9a9876a2-a2fd-40d9-b215-3e6c8207e711@huawei.com> <20230421031356.GA3048466@hori.linux.bs1.fc.nec.co.jp> <1bd6a635-5a3d-c294-38ce-5c6fcff6494f@huawei.com> <20230424064427.GA3267052@hori.linux.bs1.fc.nec.co.jp> <316b5a9e-5d5f-3bcf-57c1-86fafe6681c3@huawei.com> <6b350187-a9a5-fb37-79b1-bf69068f0182@huawei.com> <20230427023045.GA3499768@hori.linux.bs1.fc.nec.co.jp> From: Kefeng Wang In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit 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 X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: zp64tru8ehgpyeujwxirw4sqb1task67 X-Rspamd-Queue-Id: 3AFB12000F X-HE-Tag: 1682672397-113074 X-HE-Meta: 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 HQU/v//H sB9/iqvicmnPT4FHvJ5aGLJZPhtWZ6yev+YI36WZUcj7OQAclSqVi6Bpd4xj926/7Ym9K88m6oD1ZQR3KxYZPlFkwht4peDKCGgZZkQORrZDr4zfOzyctfHiEqJzs5KK4Ld9/qMec+4sGt1TKYH6WEXOYvglNfDkjJgDK6RkSq+L7DalxKZZG96cuHGImA6K1hsF4wjkXB4VV35Ak7T3Ysl7BSx2q78Az5B8rUrMhbJEpelwSKBggcG3zpw== 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 2023/4/28 0:45, Luck, Tony wrote: >>> But in the core dump case there is no return to user. The process is being >>> terminated by the signal that leads to this core dump. So even though you >>> may consider the page being accessed to be a "user" page, you can't fix >>> it by queueing work to run on return to user. >> >> For coredump，the task work will be called too, see following code, >> >> get_signal >> sig_kernel_coredump >> elf_core_dump >> dump_user_range >> _copy_from_iter // with MC-safe copy, return without panic >> do_group_exit(ksig->info.si_signo); >> do_exit >> exit_task_work >> task_work_run >> kill_me_never >> memory_failure >> > > Nice. I didn't realize that the exit code path would clear any pending task_work() requests. > But it makes sense that this happens. Thanks for filling a gap in my knowledge. > Yep, we could be benefit from it to unify memory failure handling :) > -Tony