Re: [PATCH v2] mm: hwpoison: coredump: support recovery from dump_user_range()

[Kefeng Wang <wangkefeng.wang@huawei.com>]

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