On 06/23/23 16:40, Jiaqi Yan wrote:
> Adds the functionality to tell if a subpage of a hugetlb folio is a
> raw HWPOISON page. This functionality relies on RawHwpUnreliable to
> be not set; otherwise hugepage's HWPOISON list becomes meaningless.
>
> Exports this functionality to be immediately used in the read operation
> for hugetlbfs.
>
> Signed-off-by: Jiaqi Yan <jiaqiyan@xxxxxxxxxx>
> ---
> include/linux/hugetlb.h | 19 +++++++++++++++++++
> include/linux/mm.h | 7 +++++++
> mm/hugetlb.c | 10 ++++++++++
> mm/memory-failure.c | 34 ++++++++++++++++++++++++----------
> 4 files changed, 60 insertions(+), 10 deletions(-)
>
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index 21f942025fec..8b73a12b7b38 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -1013,6 +1013,25 @@ void hugetlb_register_node(struct node *node);
> void hugetlb_unregister_node(struct node *node);
> #endif
>
> +/*
> + * Struct raw_hwp_page represents information about "raw error page",
> + * constructing singly linked list from ->_hugetlb_hwpoison field of folio.
> + */
> +struct raw_hwp_page {
> + struct llist_node node;
> + struct page *page;
> +};
> +
> +static inline struct llist_head *raw_hwp_list_head(struct folio *folio)
> +{
> + return (struct llist_head *)&folio->_hugetlb_hwpoison;
> +}
> +
> +/*
> + * Check if a given raw @subpage in a hugepage @folio is HWPOISON.
> + */
> +bool is_raw_hwp_subpage(struct folio *folio, struct page *subpage);
> +
> #else /* CONFIG_HUGETLB_PAGE */
> struct hstate {};
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 66032f0d515c..41a283bd41a7 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -3671,6 +3671,7 @@ extern const struct attribute_group memory_failure_attr_group;
> extern void memory_failure_queue(unsigned long pfn, int flags);
> extern int __get_huge_page_for_hwpoison(unsigned long pfn, int flags,
> bool *migratable_cleared);
> +extern bool __is_raw_hwp_subpage(struct folio *folio, struct page *subpage);
> void num_poisoned_pages_inc(unsigned long pfn);
> void num_poisoned_pages_sub(unsigned long pfn, long i);
> struct task_struct *task_early_kill(struct task_struct *tsk, int force_early);
> @@ -3685,6 +3686,12 @@ static inline int __get_huge_page_for_hwpoison(unsigned long pfn, int flags,
> return 0;
> }
>
> +static inline bool __is_raw_hwp_subpage(struct folio *folio,
> + struct page *subpage)
> +{
> + return false;
> +}
> +
> static inline void num_poisoned_pages_inc(unsigned long pfn)
> {
> }
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index ea24718db4af..6b860de87590 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -7377,6 +7377,16 @@ int get_huge_page_for_hwpoison(unsigned long pfn, int flags,
> return ret;
> }
>
> +bool is_raw_hwp_subpage(struct folio *folio, struct page *subpage)
> +{
> + bool ret;
> +
> + spin_lock_irq(&hugetlb_lock);
> + ret = __is_raw_hwp_subpage(folio, subpage);
> + spin_unlock_irq(&hugetlb_lock);
Can you describe what races the hugetlb_lock prevents here?
--
Mike Kravetz
> + return ret;
> +}
> +
> void folio_putback_active_hugetlb(struct folio *folio)
> {
> spin_lock_irq(&hugetlb_lock);
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index c415c3c462a3..891248e2930e 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1809,18 +1809,32 @@ EXPORT_SYMBOL_GPL(mf_dax_kill_procs);
> #endif /* CONFIG_FS_DAX */
>
> #ifdef CONFIG_HUGETLB_PAGE
> -/*
> - * Struct raw_hwp_page represents information about "raw error page",
> - * constructing singly linked list from ->_hugetlb_hwpoison field of folio.
> - */
> -struct raw_hwp_page {
> - struct llist_node node;
> - struct page *page;
> -};
>
> -static inline struct llist_head *raw_hwp_list_head(struct folio *folio)
> +bool __is_raw_hwp_subpage(struct folio *folio, struct page *subpage)
> {
> - return (struct llist_head *)&folio->_hugetlb_hwpoison;
> + struct llist_head *raw_hwp_head;
> + struct raw_hwp_page *p, *tmp;
> + bool ret = false;
> +
> + if (!folio_test_hwpoison(folio))
> + return false;
> +
> + /*
> + * When RawHwpUnreliable is set, kernel lost track of which subpages
> + * are HWPOISON. So return as if ALL subpages are HWPOISONed.
> + */
> + if (folio_test_hugetlb_raw_hwp_unreliable(folio))
> + return true;
> +
> + raw_hwp_head = raw_hwp_list_head(folio);
> + llist_for_each_entry_safe(p, tmp, raw_hwp_head->first, node) {
> + if (subpage == p->page) {
> + ret = true;
> + break;
> + }
> + }
> +
> + return ret;
> }
>
> static unsigned long __folio_free_raw_hwp(struct folio *folio, bool move_flag)
> --
> 2.41.0.162.gfafddb0af9-goog
>
