linux-kernel - Re: [PATCH 3/3] mm/memory-failure: send SIGBUS in the event of thp split fail

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Date: Wed, 8 May 2024 09:56:12 -0700
From: Jane Chu <jane.chu@...cle.com>
To: Miaohe Lin <linmiaohe@...wei.com>, nao.horiguchi@...il.com,
        akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] mm/memory-failure: send SIGBUS in the event of thp
 split fail

On 5/8/2024 2:03 AM, Miaohe Lin wrote:

> On 2024/5/2 7:24, Jane Chu wrote:
>> When handle hwpoison in a GUP longterm pin'ed thp page,
>> try_to_split_thp_page() will fail. And at this point, there is little else
>> the kernel could do except sending a SIGBUS to the user process, thus
>> give it a chance to recover.
> It seems the user process will still receive SIGBUS via kill_accessing_process()
> when (re-)access thp later. So they should have a chance to recover already.
> Or am I miss something?

The concern is about real UE consumption in which case, it's desirable 
to kill the process ASAP without having to relying on subsequent 
access.  Also to honor processes' MCE-early-kill request. 
kill_accessing_process() is very conservative in that, it doesn't check 
other processes that have the poisoned page mapped.

thanks,

-jane

>
> Thanks.
> .
>
>