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    Subject[PATCH 5.19 0765/1157] mm/migration: return errno when isolate_huge_page failed
    Date
    From: Miaohe Lin <linmiaohe@huawei.com>

    [ Upstream commit 7ce82f4c3f3ead13a9d9498768e3b1a79975c4d8 ]

    We might fail to isolate huge page due to e.g. the page is under
    migration which cleared HPageMigratable. We should return errno in this
    case rather than always return 1 which could confuse the user, i.e. the
    caller might think all of the memory is migrated while the hugetlb page is
    left behind. We make the prototype of isolate_huge_page consistent with
    isolate_lru_page as suggested by Huang Ying and rename isolate_huge_page
    to isolate_hugetlb as suggested by Muchun to improve the readability.

    Link: https://lkml.kernel.org/r/20220530113016.16663-4-linmiaohe@huawei.com
    Fixes: e8db67eb0ded ("mm: migrate: move_pages() supports thp migration")
    Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
    Suggested-by: Huang Ying <ying.huang@intel.com>
    Reported-by: kernel test robot <lkp@intel.com> (build error)
    Cc: Alistair Popple <apopple@nvidia.com>
    Cc: Christoph Hellwig <hch@lst.de>
    Cc: Christoph Lameter <cl@linux.com>
    Cc: David Hildenbrand <david@redhat.com>
    Cc: David Howells <dhowells@redhat.com>
    Cc: Mike Kravetz <mike.kravetz@oracle.com>
    Cc: Muchun Song <songmuchun@bytedance.com>
    Cc: Oscar Salvador <osalvador@suse.de>
    Cc: Peter Xu <peterx@redhat.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    include/linux/hugetlb.h | 6 +++---
    mm/gup.c | 2 +-
    mm/hugetlb.c | 11 +++++------
    mm/memory-failure.c | 2 +-
    mm/memory_hotplug.c | 2 +-
    mm/mempolicy.c | 2 +-
    mm/migrate.c | 7 ++++---
    7 files changed, 16 insertions(+), 16 deletions(-)

    diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
    index e4cff27d1198..756b66ff025e 100644
    --- a/include/linux/hugetlb.h
    +++ b/include/linux/hugetlb.h
    @@ -170,7 +170,7 @@ bool hugetlb_reserve_pages(struct inode *inode, long from, long to,
    vm_flags_t vm_flags);
    long hugetlb_unreserve_pages(struct inode *inode, long start, long end,
    long freed);
    -bool isolate_huge_page(struct page *page, struct list_head *list);
    +int isolate_hugetlb(struct page *page, struct list_head *list);
    int get_hwpoison_huge_page(struct page *page, bool *hugetlb);
    int get_huge_page_for_hwpoison(unsigned long pfn, int flags);
    void putback_active_hugepage(struct page *page);
    @@ -376,9 +376,9 @@ static inline pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr,
    return NULL;
    }

    -static inline bool isolate_huge_page(struct page *page, struct list_head *list)
    +static inline int isolate_hugetlb(struct page *page, struct list_head *list)
    {
    - return false;
    + return -EBUSY;
    }

    static inline int get_hwpoison_huge_page(struct page *page, bool *hugetlb)
    diff --git a/mm/gup.c b/mm/gup.c
    index e2a39e30756d..fd3262ae92fc 100644
    --- a/mm/gup.c
    +++ b/mm/gup.c
    @@ -1900,7 +1900,7 @@ static long check_and_migrate_movable_pages(unsigned long nr_pages,
    * Try to move out any movable page before pinning the range.
    */
    if (folio_test_hugetlb(folio)) {
    - if (!isolate_huge_page(&folio->page,
    + if (isolate_hugetlb(&folio->page,
    &movable_page_list))
    isolation_error_count++;
    continue;
    diff --git a/mm/hugetlb.c b/mm/hugetlb.c
    index a18c071c294e..b7f007399be2 100644
    --- a/mm/hugetlb.c
    +++ b/mm/hugetlb.c
    @@ -2766,8 +2766,7 @@ static int alloc_and_dissolve_huge_page(struct hstate *h, struct page *old_page,
    * Fail with -EBUSY if not possible.
    */
    spin_unlock_irq(&hugetlb_lock);
    - if (!isolate_huge_page(old_page, list))
    - ret = -EBUSY;
    + ret = isolate_hugetlb(old_page, list);
    spin_lock_irq(&hugetlb_lock);
    goto free_new;
    } else if (!HPageFreed(old_page)) {
    @@ -2843,7 +2842,7 @@ int isolate_or_dissolve_huge_page(struct page *page, struct list_head *list)
    if (hstate_is_gigantic(h))
    return -ENOMEM;

    - if (page_count(head) && isolate_huge_page(head, list))
    + if (page_count(head) && !isolate_hugetlb(head, list))
    ret = 0;
    else if (!page_count(head))
    ret = alloc_and_dissolve_huge_page(h, head, list);
    @@ -6966,15 +6965,15 @@ follow_huge_pgd(struct mm_struct *mm, unsigned long address, pgd_t *pgd, int fla
    return pte_page(*(pte_t *)pgd) + ((address & ~PGDIR_MASK) >> PAGE_SHIFT);
    }

    -bool isolate_huge_page(struct page *page, struct list_head *list)
    +int isolate_hugetlb(struct page *page, struct list_head *list)
    {
    - bool ret = true;
    + int ret = 0;

    spin_lock_irq(&hugetlb_lock);
    if (!PageHeadHuge(page) ||
    !HPageMigratable(page) ||
    !get_page_unless_zero(page)) {
    - ret = false;
    + ret = -EBUSY;
    goto unlock;
    }
    ClearHPageMigratable(page);
    diff --git a/mm/memory-failure.c b/mm/memory-failure.c
    index da39ec8afca8..845369f839e1 100644
    --- a/mm/memory-failure.c
    +++ b/mm/memory-failure.c
    @@ -2178,7 +2178,7 @@ static bool isolate_page(struct page *page, struct list_head *pagelist)
    bool lru = PageLRU(page);

    if (PageHuge(page)) {
    - isolated = isolate_huge_page(page, pagelist);
    + isolated = !isolate_hugetlb(page, pagelist);
    } else {
    if (lru)
    isolated = !isolate_lru_page(page);
    diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
    index 1213d0c67a53..649a50ed90f3 100644
    --- a/mm/memory_hotplug.c
    +++ b/mm/memory_hotplug.c
    @@ -1643,7 +1643,7 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)

    if (PageHuge(page)) {
    pfn = page_to_pfn(head) + compound_nr(head) - 1;
    - isolate_huge_page(head, &source);
    + isolate_hugetlb(head, &source);
    continue;
    } else if (PageTransHuge(page))
    pfn = page_to_pfn(head) + thp_nr_pages(page) - 1;
    diff --git a/mm/mempolicy.c b/mm/mempolicy.c
    index d39b01fd52fe..9689919a2829 100644
    --- a/mm/mempolicy.c
    +++ b/mm/mempolicy.c
    @@ -602,7 +602,7 @@ static int queue_pages_hugetlb(pte_t *pte, unsigned long hmask,
    /* With MPOL_MF_MOVE, we migrate only unshared hugepage. */
    if (flags & (MPOL_MF_MOVE_ALL) ||
    (flags & MPOL_MF_MOVE && page_mapcount(page) == 1)) {
    - if (!isolate_huge_page(page, qp->pagelist) &&
    + if (isolate_hugetlb(page, qp->pagelist) &&
    (flags & MPOL_MF_STRICT))
    /*
    * Failed to isolate page but allow migrating pages
    diff --git a/mm/migrate.c b/mm/migrate.c
    index 6c1ea61f39d8..29b9faed4136 100644
    --- a/mm/migrate.c
    +++ b/mm/migrate.c
    @@ -133,7 +133,7 @@ static void putback_movable_page(struct page *page)
    *
    * This function shall be used whenever the isolated pageset has been
    * built from lru, balloon, hugetlbfs page. See isolate_migratepages_range()
    - * and isolate_huge_page().
    + * and isolate_hugetlb().
    */
    void putback_movable_pages(struct list_head *l)
    {
    @@ -1633,8 +1633,9 @@ static int add_page_for_migration(struct mm_struct *mm, unsigned long addr,

    if (PageHuge(page)) {
    if (PageHead(page)) {
    - isolate_huge_page(page, pagelist);
    - err = 1;
    + err = isolate_hugetlb(page, pagelist);
    + if (!err)
    + err = 1;
    }
    } else {
    struct page *head;
    --
    2.35.1


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