Re: [PATCH v2] mm: clean up hwpoison page cache page in fault path

[Oscar Salvador <osalvador@suse.de>]

On Sat, Feb 12, 2022 at 09:37:40PM -0500, Rik van Riel wrote:
> Sometimes the page offlining code can leave behind a hwpoisoned clean
> page cache page. This can lead to programs being killed over and over
> and over again as they fault in the hwpoisoned page, get killed, and
> then get re-spawned by whatever wanted to run them.
> 
> This is particularly embarrassing when the page was offlined due to
> having too many corrected memory errors. Now we are killing tasks
> due to them trying to access memory that probably isn't even corrupted.
> 
> This problem can be avoided by invalidating the page from the page
> fault handler, which already has a branch for dealing with these
> kinds of pages. With this patch we simply pretend the page fault
> was successful if the page was invalidated, return to userspace,
> incur another page fault, read in the file from disk (to a new
> memory page), and then everything works again.
> 
> Signed-off-by: Rik van Riel <riel@surriel.com>
> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>

Although I would really loved to understand how we got there,
it fixes the problem, so:

Reviewed-by: Oscar Salvador <osalvador@suse.de>

-- 
Oscar Salvador
SUSE Labs