On Mon, Aug 16, 2021 at 10:37 PM Naoya Horiguchi
<naoya.horiguchi@xxxxxxxxx> wrote:
>
> From: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
>
> HWPoisonHandlable() sometimes returns false for typical user pages
> due to races with average memory events like transfers over LRU lists.
> This causes failures in hwpoison handling.
>
> There's retry code for such a case but does not work because the retry
> loop reaches the retry limit too quickly before the page settles down to
> handlable state. Let get_any_page() call shake_page() to fix it.
>
> Fixes: 25182f05ffed ("mm,hwpoison: fix race with hugetlb page allocation")
> Reported-by: Tony Luck <tony.luck@xxxxxxxxx>
> Signed-off-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx # 5.13
> ---
> mm/memory-failure.c | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git v5.14-rc6/mm/memory-failure.c v5.14-rc6_patched/mm/memory-failure.c
> index eefd823deb67..aa6592540f17 100644
> --- v5.14-rc6/mm/memory-failure.c
> +++ v5.14-rc6_patched/mm/memory-failure.c
> @@ -1146,7 +1146,7 @@ static int __get_hwpoison_page(struct page *page)
> * unexpected races caused by taking a page refcount.
> */
> if (!HWPoisonHandlable(head))
> - return 0;
> + return -EBUSY;
>
> if (PageTransHuge(head)) {
> /*
> @@ -1199,9 +1199,14 @@ static int get_any_page(struct page *p, unsigned long flags)
> }
> goto out;
> } else if (ret == -EBUSY) {
> - /* We raced with freeing huge page to buddy, retry. */
> - if (pass++ < 3)
> + /*
> + * We raced with (possibly temporary) unhandlable
> + * page, retry.
> + */
> + if (pass++ < 3) {
> + shake_page(p, 1);
> goto try_again;
> + }
I think the return value should be set to -EIO before jumping to out.
I'm supposed -EIO means this is really or very likely an unhandlable
page.
> goto out;
> }
> }
> --
> 2.25.1
>
>
