From: Miaohe Lin Subject: mm/migration: return errno when isolate_huge_page failed We might fail to isolate huge page due to e.g. the page is under migration which cleared HPageMigratable. So we should return -EBUSY in this case rather than always return 1 which could confuse the user. Also we make the prototype of isolate_huge_page consistent with isolate_lru_page to improve the readability. Link: https://lkml.kernel.org/r/20220425132723.34824-4-linmiaohe@huawei.com Fixes: e8db67eb0ded ("mm: migrate: move_pages() supports thp migration") Signed-off-by: Miaohe Lin Suggested-by: Huang Ying Cc: Christoph Hellwig Cc: Christoph Lameter Cc: David Hildenbrand Cc: David Howells Cc: Mike Kravetz Cc: Muchun Song Cc: Naoya Horiguchi Cc: Mel Gorman Signed-off-by: Andrew Morton --- include/linux/hugetlb.h | 6 +++--- mm/gup.c | 2 +- mm/hugetlb.c | 11 +++++------ mm/memory-failure.c | 2 +- mm/mempolicy.c | 2 +- mm/migrate.c | 5 +++-- 6 files changed, 14 insertions(+), 14 deletions(-) --- a/include/linux/hugetlb.h~mm-migration-return-errno-when-isolate_huge_page-failed +++ a/include/linux/hugetlb.h @@ -170,7 +170,7 @@ bool hugetlb_reserve_pages(struct inode 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_huge_page(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(str return NULL; } -static inline bool isolate_huge_page(struct page *page, struct list_head *list) +static inline int isolate_huge_page(struct page *page, struct list_head *list) { - return false; + return -EBUSY; } static inline int get_hwpoison_huge_page(struct page *page, bool *hugetlb) --- a/mm/gup.c~mm-migration-return-errno-when-isolate_huge_page-failed +++ a/mm/gup.c @@ -1869,7 +1869,7 @@ static long check_and_migrate_movable_pa * Try to move out any movable page before pinning the range. */ if (folio_test_hugetlb(folio)) { - if (!isolate_huge_page(&folio->page, + if (isolate_huge_page(&folio->page, &movable_page_list)) isolation_error_count++; continue; --- a/mm/hugetlb.c~mm-migration-return-errno-when-isolate_huge_page-failed +++ a/mm/hugetlb.c @@ -2765,8 +2765,7 @@ retry: * Fail with -EBUSY if not possible. */ spin_unlock_irq(&hugetlb_lock); - if (!isolate_huge_page(old_page, list)) - ret = -EBUSY; + ret = isolate_huge_page(old_page, list); spin_lock_irq(&hugetlb_lock); goto free_new; } else if (!HPageFreed(old_page)) { @@ -2842,7 +2841,7 @@ int isolate_or_dissolve_huge_page(struct if (hstate_is_gigantic(h)) return -ENOMEM; - if (page_count(head) && isolate_huge_page(head, list)) + if (page_count(head) && !isolate_huge_page(head, list)) ret = 0; else if (!page_count(head)) ret = alloc_and_dissolve_huge_page(h, head, list); @@ -6932,15 +6931,15 @@ follow_huge_pgd(struct mm_struct *mm, un return pte_page(*(pte_t *)pgd) + ((address & ~PGDIR_MASK) >> PAGE_SHIFT); } -bool isolate_huge_page(struct page *page, struct list_head *list) +int isolate_huge_page(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); --- a/mm/memory-failure.c~mm-migration-return-errno-when-isolate_huge_page-failed +++ a/mm/memory-failure.c @@ -2203,7 +2203,7 @@ static bool isolate_page(struct page *pa bool lru = PageLRU(page); if (PageHuge(page)) { - isolated = isolate_huge_page(page, pagelist); + isolated = !isolate_huge_page(page, pagelist); } else { if (lru) isolated = !isolate_lru_page(page); --- a/mm/mempolicy.c~mm-migration-return-errno-when-isolate_huge_page-failed +++ a/mm/mempolicy.c @@ -602,7 +602,7 @@ static int queue_pages_hugetlb(pte_t *pt /* 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_huge_page(page, qp->pagelist) && (flags & MPOL_MF_STRICT)) /* * Failed to isolate page but allow migrating pages --- a/mm/migrate.c~mm-migration-return-errno-when-isolate_huge_page-failed +++ a/mm/migrate.c @@ -1628,8 +1628,9 @@ static int add_page_for_migration(struct if (PageHuge(page)) { if (PageHead(page)) { - isolate_huge_page(page, pagelist); - err = 1; + err = isolate_huge_page(page, pagelist); + if (!err) + err = 1; } } else { struct page *head; _