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Message-ID: <3c66e7f6-e499-9802-409a-a32404fc87cc@huawei.com>
Date: Mon, 11 Jul 2022 15:09:01 +0800
From: Miaohe Lin <linmiaohe@...wei.com>
To: Naoya Horiguchi <naoya.horiguchi@...ux.dev>, <linux-mm@...ck.org>
CC: Andrew Morton <akpm@...ux-foundation.org>,
David Hildenbrand <david@...hat.com>,
Mike Kravetz <mike.kravetz@...cle.com>,
Liu Shixin <liushixin2@...wei.com>,
Yang Shi <shy828301@...il.com>,
Oscar Salvador <osalvador@...e.de>,
Muchun Song <songmuchun@...edance.com>,
Naoya Horiguchi <naoya.horiguchi@....com>,
<linux-kernel@...r.kernel.org>
Subject: Re: [mm-unstable PATCH v5 4/8] mm, hwpoison: make unpoison aware of
raw error info in hwpoisoned hugepage
On 2022/7/8 13:36, Naoya Horiguchi wrote:
> From: Naoya Horiguchi <naoya.horiguchi@....com>
>
> 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.
>
> HPageVmemmapOptimized(hpage) and HPageRawHwpUnreliable(hpage)) can't be
> unpoisoned, so let's skip them.
>
> Signed-off-by: Naoya Horiguchi <naoya.horiguchi@....com>
> Reported-by: kernel test robot <lkp@...el.com>
> ---
> v4 -> v5:
> - fix type of return value of free_raw_hwp_pages()
> (found by kernel test robot),
> - prevent unpoison for HPageVmemmapOptimized and HPageRawHwpUnreliable.
> ---
> include/linux/swapops.h | 9 ++++++++
> mm/memory-failure.c | 50 ++++++++++++++++++++++++++++++++++++-----
> 2 files changed, 53 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 6833c5e4b410..89e74ec8a95f 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1720,22 +1720,41 @@ static int hugetlb_set_page_hwpoison(struct page *hpage, struct page *page)
> return ret;
> }
>
> -int hugetlb_clear_page_hwpoison(struct page *hpage)
> +static long free_raw_hwp_pages(struct page *hpage, bool move_flag)
NO strong opinion: Maybe the return type should be "unsigned" as it always >= 0 ?
> {
> struct llist_head *head;
> struct llist_node *t, *tnode;
> + long count = 0;
>
> - if (!HPageRawHwpUnreliable(hpage))
> - ClearPageHWPoison(hpage);
> + /*
> + * HPageVmemmapOptimized hugepages can't be unpoisoned because
> + * struct pages for tail pages are required to free hwpoisoned
> + * hugepages. HPageRawHwpUnreliable hugepages shouldn't be
> + * unpoisoned by definition.
> + */
> + if (HPageVmemmapOptimized(hpage) || HPageRawHwpUnreliable(hpage))
> + return 0;
> 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;
> +}
> +
> +int hugetlb_clear_page_hwpoison(struct page *hpage)
It seems the return value is unused?
> +{
> + int ret = -EBUSY;
> +
> + if (!HPageRawHwpUnreliable(hpage))
> + ret = !TestClearPageHWPoison(hpage);
> + free_raw_hwp_pages(hpage, true);
> + return ret;
> }
>
> /*
> @@ -1879,6 +1898,10 @@ static inline int try_memory_failure_hugetlb(unsigned long pfn, int flags, int *
> return 0;
> }
>
> +static inline long free_raw_hwp_pages(struct page *hpage, bool move_flag)
If return type is changed, remember to change here too.
> +{
> + return 0;
> +}
> #endif /* CONFIG_HUGETLB_PAGE */
>
> static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
> @@ -2284,6 +2307,7 @@ int unpoison_memory(unsigned long pfn)
> struct page *p;
> int ret = -EBUSY;
> int freeit = 0;
> + long count = 1;
> static DEFINE_RATELIMIT_STATE(unpoison_rs, DEFAULT_RATELIMIT_INTERVAL,
> DEFAULT_RATELIMIT_BURST);
>
> @@ -2331,6 +2355,13 @@ 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);
It seems the current behavior is: if any subpage of a hugetlb page is unpoisoned, then all of the
hwpoisoned subpages will be unpoisoned. I'm not sure whether this is what we want.
Thanks.
> + if (count == 0) {
> + ret = -EBUSY;
> + goto unlock_mutex;
> + }
> + }
> ret = TestClearPageHWPoison(page) ? 0 : -EBUSY;
> } else if (ret < 0) {
> if (ret == -EHWPOISON) {
> @@ -2339,6 +2370,13 @@ 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);
> + if (count == 0) {
> + ret = -EBUSY;
> + goto unlock_mutex;
> + }
> + }
> freeit = !!TestClearPageHWPoison(p);
>
> put_page(page);
> @@ -2351,7 +2389,7 @@ 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);
> }
>
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