On 2022/2/12 6:05, 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
Yep, __soft_offline_page tries to invalidate_inode_page in a lightway.
> 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@xxxxxxxxxxx>
Good catch! This looks good to me. Thanks.
Reviewed-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
>
> diff --git a/mm/memory.c b/mm/memory.c
> index c125c4969913..2300358e268c 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -3871,11 +3871,16 @@ static vm_fault_t __do_fault(struct vm_fault *vmf)
> return ret;
>
> if (unlikely(PageHWPoison(vmf->page))) {
> - if (ret & VM_FAULT_LOCKED)
> + int poisonret = VM_FAULT_HWPOISON;
> + if (ret & VM_FAULT_LOCKED) {
> + /* Retry if a clean page was removed from the cache. */
> + if (invalidate_inode_page(vmf->page))
> + poisonret = 0;
> unlock_page(vmf->page);
> + }
> put_page(vmf->page);
> vmf->page = NULL;
> - return VM_FAULT_HWPOISON;
> + return poisonret;
> }
>
> if (unlikely(!(ret & VM_FAULT_LOCKED)))
>
>
