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

[Andrew Morton]

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

At first scan I thought this was a code cleanup.

I think I'll do s/clean up/invalidate/.

On Sat, 12 Feb 2022 21:37:40 -0500 Rik van Riel <riel@xxxxxxxxxxx> wrote:

> Sometimes the page offlining code can leave behind a hwpoisoned clean
> page cache page.

Is this correct behaviour?

> 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.

Is this worth a cc:stable?