On Mon 08-03-21 18:28:03, Muchun Song wrote:
> Because we reuse the first tail vmemmap page frame and remap it
> with read-only, we cannot set the PageHWPosion on some tail pages.
> So we can use the head[4].private (There are at least 128 struct
> page structures associated with the optimized HugeTLB page, so
> using head[4].private is safe) to record the real error page index
> and set the raw error page PageHWPoison later.
Can we have more poisoned tail pages? Also who does consume that index
and set the HWPoison on the proper tail page?
> Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
> Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
> Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
> Tested-by: Chen Huang <chenhuang5@xxxxxxxxxx>
> Tested-by: Bodeddula Balasubramaniam <bodeddub@xxxxxxxxxx>
> ---
> mm/hugetlb.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++++++------
> 1 file changed, 72 insertions(+), 8 deletions(-)
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 377e0c1b283f..c0c1b7635ca9 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1304,6 +1304,74 @@ static inline void destroy_compound_gigantic_page(struct page *page,
> unsigned int order) { }
> #endif
>
> +#ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP
> +static inline void hwpoison_subpage_deliver(struct hstate *h, struct page *head)
> +{
> + struct page *page;
> +
> + if (!PageHWPoison(head) || !free_vmemmap_pages_per_hpage(h))
> + return;
> +
> + 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 hwpoison_subpage_set(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);
> + } else if (page != head) {
> + /*
> + * Move PageHWPoison flag from head page to the raw error page,
> + * which makes any subpages rather than the error page reusable.
> + */
> + SetPageHWPoison(page);
> + ClearPageHWPoison(head);
> + }
> +}
> +
> +static inline void hwpoison_subpage_clear(struct hstate *h, struct page *head)
> +{
> + if (!PageHWPoison(head) || !free_vmemmap_pages_per_hpage(h))
> + return;
> +
> + set_page_private(head + 4, 0);
> +}
> +#else
> +static inline void hwpoison_subpage_deliver(struct hstate *h, struct page *head)
> +{
> +}
> +
> +static inline void hwpoison_subpage_set(struct hstate *h, struct page *head,
> + struct page *page)
> +{
> + if (PageHWPoison(head) && page != head) {
> + /*
> + * Move PageHWPoison flag from head page to the raw error page,
> + * which makes any subpages rather than the error page reusable.
> + */
> + SetPageHWPoison(page);
> + ClearPageHWPoison(head);
> + }
> +}
> +
> +static inline void hwpoison_subpage_clear(struct hstate *h, struct page *head)
> +{
> +}
> +#endif
> +
> static int update_and_free_page(struct hstate *h, struct page *page)
> __releases(&hugetlb_lock) __acquires(&hugetlb_lock)
> {
> @@ -1357,6 +1425,8 @@ static int update_and_free_page(struct hstate *h, struct page *page)
> return -ENOMEM;
> }
>
> + hwpoison_subpage_deliver(h, page);
> +
> for (i = 0; i < pages_per_huge_page(h);
> i++, subpage = mem_map_next(subpage, page, i)) {
> subpage->flags &= ~(1 << PG_locked | 1 << PG_error |
> @@ -1801,14 +1871,7 @@ int dissolve_free_huge_page(struct page *page)
> goto retry;
> }
>
> - /*
> - * 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);
> - }
> + hwpoison_subpage_set(h, head, page);
> list_del(&head->lru);
> h->free_huge_pages--;
> h->free_huge_pages_node[nid]--;
> @@ -1818,6 +1881,7 @@ int dissolve_free_huge_page(struct page *page)
> h->surplus_huge_pages--;
> h->surplus_huge_pages_node[nid]--;
> h->max_huge_pages++;
> + hwpoison_subpage_clear(h, head);
> }
> }
> out:
> --
> 2.11.0
>
--
Michal Hocko
SUSE Labs
