Re: [PATCH v8 07/12] mm/hugetlb: Set the PageHWPoison to the raw error page

[Muchun Song <songmuchun@bytedance.com>]

On Thu, Dec 10, 2020 at 11:58 AM Muchun Song <songmuchun@bytedance.com> wrote:
>
> Because we reuse the first tail vmemmap page frame and remap it
> with read-only, we cannot set the PageHWPosion on a tail page.
> So we can use the head[4].mapping to record the real error page
                              ^^^
                             private

A typo. Will update the next version. Thanks.

> index and set the raw error page PageHWPoison later.
>
> Signed-off-by: Muchun Song <songmuchun@bytedance.com>
> ---
>  mm/hugetlb.c | 52 ++++++++++++++++++++++++++++++++++++++++++++--------
>  1 file changed, 44 insertions(+), 8 deletions(-)
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 542e6cb81321..06157df08d8e 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1347,6 +1347,47 @@ static inline void __update_and_free_page(struct hstate *h, struct page *page)
>                 schedule_work(&hpage_update_work);
>  }
>
> +static inline void subpage_hwpoison_deliver(struct hstate *h, struct page *head)
> +{
> +       struct page *page = head;
> +
> +       if (!free_vmemmap_pages_per_hpage(h))
> +               return;
> +
> +       if (PageHWPoison(head))
> +               page = head + page_private(head + 4);
> +
> +       /*
> +        * Move PageHWPoison flag from head page to the raw error page,
> +        * which makes any subpages rather than the error page reusable.
> +        */
> +       if (page != head) {
> +               SetPageHWPoison(page);
> +               ClearPageHWPoison(head);
> +       }
> +}
> +
> +static inline void set_subpage_hwpoison(struct hstate *h, struct page *head,
> +                                       struct page *page)
> +{
> +       if (!PageHWPoison(head))
> +               return;
> +
> +       if (free_vmemmap_pages_per_hpage(h)) {
> +               set_page_private(head + 4, page - head);
> +               return;
> +       }
> +
> +       /*
> +        * Move PageHWPoison flag from head page to the raw error page,
> +        * which makes any subpages rather than the error page reusable.
> +        */
> +       if (page != head) {
> +               SetPageHWPoison(page);
> +               ClearPageHWPoison(head);
> +       }
> +}
> +
>  static void update_and_free_page(struct hstate *h, struct page *page)
>  {
>         if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported())
> @@ -1363,6 +1404,7 @@ static void __free_hugepage(struct hstate *h, struct page *page)
>         int i;
>
>         alloc_huge_page_vmemmap(h, page);
> +       subpage_hwpoison_deliver(h, page);
>
>         for (i = 0; i < pages_per_huge_page(h); i++) {
>                 page[i].flags &= ~(1 << PG_locked | 1 << PG_error |
> @@ -1840,14 +1882,8 @@ int dissolve_free_huge_page(struct page *page)
>                 int nid = page_to_nid(head);
>                 if (h->free_huge_pages - h->resv_huge_pages == 0)
>                         goto out;
> -               /*
> -                * Move PageHWPoison flag from head page to the raw error page,
> -                * which makes any subpages rather than the error page reusable.
> -                */
> -               if (PageHWPoison(head) && page != head) {
> -                       SetPageHWPoison(page);
> -                       ClearPageHWPoison(head);
> -               }
> +
> +               set_subpage_hwpoison(h, head, page);
>                 list_del(&head->lru);
>                 h->free_huge_pages--;
>                 h->free_huge_pages_node[nid]--;
> --
> 2.11.0
>


-- 
Yours,
Muchun