Re: [PATCH] mm,hwpoison: check mm when killing accessing process

[Naoya Horiguchi]

On Wed, Sep 14, 2022 at 02:49:35PM +0800, Shuai Xue wrote:
> The GHES code calls memory_failure_queue() from IRQ context to queue work
> into workqueue and schedule it on the current CPU. Then the work is
> processed in memory_failure_work_func() by kworker and calls
> memory_failure().
>
> When a page is already poisoned, commit a3f5d80ea401 ("mm,hwpoison: send
> SIGBUS with error virutal address") make memory_failure() call
> kill_accessing_process() that:
>
>     - holds mmap locking of current->mm
>     - does pagetable walk to find the error virtual address
>     - and sends SIGBUS to the current process with error info.
>
> However, the mm of kworker is not valid. Therefore, check mm when killing
> accessing process.
>
> Fixes: a3f5d80ea401 ("mm,hwpoison: send SIGBUS with error virutal address")
> Signed-off-by: Shuai Xue <xueshuai@xxxxxxxxxxxxxxxxx>

Thank you for the patch, the fix itself makes sense to me.
I agree with this patch with applying comments from Andrew.

Acked-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>