Re: [mm-unstable PATCH v4 5/9] mm, hwpoison: make unpoison aware of raw error info in hwpoisoned hugepage

From: Miaohe Lin
Date: Tue Jul 05 2022 - 22:59:01 EST


On 2022/7/4 9:33, Naoya Horiguchi wrote:
> From: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
>
> Raw error info list needs to be removed when hwpoisoned hugetlb is
> unpoisoned. And unpoison handler needs to know how many errors there
> are in the target hugepage. So add them.
>
> Signed-off-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
> ---
> include/linux/swapops.h | 9 +++++++++
> mm/memory-failure.c | 31 +++++++++++++++++++++++++------
> 2 files changed, 34 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/swapops.h b/include/linux/swapops.h
> index a01aeb3fcc0b..ddc98f96ad2c 100644
> --- a/include/linux/swapops.h
> +++ b/include/linux/swapops.h
> @@ -498,6 +498,11 @@ static inline void num_poisoned_pages_dec(void)
> atomic_long_dec(&num_poisoned_pages);
> }
>
> +static inline void num_poisoned_pages_sub(long i)
> +{
> + atomic_long_sub(i, &num_poisoned_pages);
> +}
> +
> #else
>
> static inline swp_entry_t make_hwpoison_entry(struct page *page)
> @@ -518,6 +523,10 @@ static inline struct page *hwpoison_entry_to_page(swp_entry_t entry)
> static inline void num_poisoned_pages_inc(void)
> {
> }
> +
> +static inline void num_poisoned_pages_sub(long i)
> +{
> +}
> #endif
>
> static inline int non_swap_entry(swp_entry_t entry)
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 53bf7486a245..6af2096d8ea0 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1722,22 +1722,33 @@ static inline int hugetlb_set_page_hwpoison(struct page *hpage,
> return ret;
> }
>
> -inline int hugetlb_clear_page_hwpoison(struct page *hpage)
> +static inline long free_raw_hwp_pages(struct page *hpage, bool move_flag)
> {
> struct llist_head *head;
> struct llist_node *t, *tnode;
> + long count = 0;
>
> - if (!HPageRawHwpUnreliable(hpage))
> - ClearPageHWPoison(hpage);
> head = raw_hwp_list_head(hpage);
> llist_for_each_safe(tnode, t, head->first) {
> struct raw_hwp_page *p = container_of(tnode, struct raw_hwp_page, node);
>
> - SetPageHWPoison(p->page);
> + if (move_flag)
> + SetPageHWPoison(p->page);
> kfree(p);
> + count++;
> }
> llist_del_all(head);
> - return 0;
> + return count;
> +}
> +
> +inline int hugetlb_clear_page_hwpoison(struct page *hpage)
> +{
> + int ret = -EBUSY;
> +
> + if (!HPageRawHwpUnreliable(hpage))
> + ret = !TestClearPageHWPoison(hpage);
> + free_raw_hwp_pages(hpage, true);
> + return ret;
> }
>
> /*
> @@ -1882,6 +1893,9 @@ static inline int try_memory_failure_hugetlb(unsigned long pfn, int flags, int *
> return 0;
> }
>
> +static inline void free_raw_hwp_pages(struct page *hpage, bool move_flag)
> +{
> +}
> #endif /* CONFIG_HUGETLB_PAGE */
>
> static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
> @@ -2287,6 +2301,7 @@ int unpoison_memory(unsigned long pfn)

Is it safe to unpoison hugepage when HPageRawHwpUnreliable? I'm afraid because
some raw error info is missing..

Thanks.

> struct page *p;
> int ret = -EBUSY;
> int freeit = 0;
> + long count = 1;
> static DEFINE_RATELIMIT_STATE(unpoison_rs, DEFAULT_RATELIMIT_INTERVAL,
> DEFAULT_RATELIMIT_BURST);
>
> @@ -2334,6 +2349,8 @@ int unpoison_memory(unsigned long pfn)
>
> ret = get_hwpoison_page(p, MF_UNPOISON);
> if (!ret) {
> + if (PageHuge(p))
> + count = free_raw_hwp_pages(page, false);
> ret = TestClearPageHWPoison(page) ? 0 : -EBUSY;
> } else if (ret < 0) {
> if (ret == -EHWPOISON) {
> @@ -2342,6 +2359,8 @@ int unpoison_memory(unsigned long pfn)
> unpoison_pr_info("Unpoison: failed to grab page %#lx\n",
> pfn, &unpoison_rs);
> } else {
> + if (PageHuge(p))
> + count = free_raw_hwp_pages(page, false);
> freeit = !!TestClearPageHWPoison(p);
>
> put_page(page);
> @@ -2354,7 +2373,7 @@ int unpoison_memory(unsigned long pfn)
> unlock_mutex:
> mutex_unlock(&mf_mutex);
> if (!ret || freeit) {
> - num_poisoned_pages_dec();
> + num_poisoned_pages_sub(count);
> unpoison_pr_info("Unpoison: Software-unpoisoned page %#lx\n",
> page_to_pfn(p), &unpoison_rs);
> }
>