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

[Kefeng Wang]

On 2023/4/25 0:17, Luck, Tony wrote:
> > > This change seems to not related to what you try to fix.
> > > Could this break some other workloads like copying from user address?
> >
> > Yes, this move MCE_IN_KERNEL_COPYIN set into next case, both COPY and
> > MCE_SAFE type will set MCE_IN_KERNEL_COPYIN, for EX_TYPE_COPY, we don't
> > break it.
>
> Should Linux even try to take a core dump for a SIGBUS generated because
> the application accessed a poisoned page?
>
> It doesn't seem like it would be useful. Core dumps are for debugging s/w
> program errors in applications and libraries. That isn't the case when there
> is a poison consumption. The application did nothing wrong.
>
> This patch is still useful though. There may be an undiscovered poison
> page in the application. Avoiding a kernel crash when dumping core
> is still a good thing.

Thanks for your confirm, and what your option about add
MCE_IN_KERNEL_COPYIN to EX_TYPE_DEFAULT_MCE_SAFE/FAULT_MCE_SAFE type
to let do_machine_check call queue_task_work(&m, msg, kill_me_never),
which kill every call memory_failure_queue() after mc safe copy return?

> -Tony