From 7f5abe609b3dcbc62a36e18b1437f4f3521ecb75 Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Mon, 9 May 2022 18:20:44 -0700 Subject: mm/rmap: fail try_to_migrate() early when setting a PMD migration entry fails Let's fail right away in case we cannot clear PG_anon_exclusive because the anon THP may be pinned. Right now, we continue trying to install migration entries and the caller of try_to_migrate() will realize that the page is still mapped and has to restore the migration entries. Let's just fail fast just like for PTE migration entries. Link: https://lkml.kernel.org/r/20220428083441.37290-14-david@redhat.com Signed-off-by: David Hildenbrand Suggested-by: Vlastimil Babka Cc: Andrea Arcangeli Cc: Christoph Hellwig Cc: David Rientjes Cc: Don Dutile Cc: Hugh Dickins Cc: Jan Kara Cc: Jann Horn Cc: Jason Gunthorpe Cc: John Hubbard Cc: Khalid Aziz Cc: "Kirill A. Shutemov" Cc: Liang Zhang Cc: "Matthew Wilcox (Oracle)" Cc: Michal Hocko Cc: Mike Kravetz Cc: Mike Rapoport Cc: Nadav Amit Cc: Oded Gabbay Cc: Oleg Nesterov Cc: Pedro Demarchi Gomes Cc: Peter Xu Cc: Rik van Riel Cc: Roman Gushchin Cc: Shakeel Butt Cc: Yang Shi Signed-off-by: Andrew Morton --- include/linux/swapops.h | 4 ++-- mm/huge_memory.c | 8 +++++--- mm/rmap.c | 6 +++++- 3 files changed, 12 insertions(+), 6 deletions(-) diff --git a/include/linux/swapops.h b/include/linux/swapops.h index 6648b97244e7..e476a8fed537 100644 --- a/include/linux/swapops.h +++ b/include/linux/swapops.h @@ -299,7 +299,7 @@ static inline bool is_pfn_swap_entry(swp_entry_t entry) struct page_vma_mapped_walk; #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION -extern void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, +extern int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, struct page *page); extern void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, @@ -332,7 +332,7 @@ static inline int is_pmd_migration_entry(pmd_t pmd) return !pmd_present(pmd) && is_migration_entry(pmd_to_swp_entry(pmd)); } #else -static inline void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, +static inline int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, struct page *page) { BUILD_BUG(); diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 231911b7bf9d..14d7fa6dc793 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -3066,7 +3066,7 @@ late_initcall(split_huge_pages_debugfs); #endif #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION -void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, +int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, struct page *page) { struct vm_area_struct *vma = pvmw->vma; @@ -3078,7 +3078,7 @@ void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, pmd_t pmdswp; if (!(pvmw->pmd && !pvmw->pte)) - return; + return 0; flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); pmdval = pmdp_invalidate(vma, address, pvmw->pmd); @@ -3086,7 +3086,7 @@ void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, anon_exclusive = PageAnon(page) && PageAnonExclusive(page); if (anon_exclusive && page_try_share_anon_rmap(page)) { set_pmd_at(mm, address, pvmw->pmd, pmdval); - return; + return -EBUSY; } if (pmd_dirty(pmdval)) @@ -3104,6 +3104,8 @@ void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, page_remove_rmap(page, vma, true); put_page(page); trace_set_migration_pmd(address, pmd_val(pmdswp)); + + return 0; } void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) diff --git a/mm/rmap.c b/mm/rmap.c index 0d63e7ce35cc..f96cc7eb23ec 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1856,7 +1856,11 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, VM_BUG_ON_FOLIO(folio_test_hugetlb(folio) || !folio_test_pmd_mappable(folio), folio); - set_pmd_migration_entry(&pvmw, subpage); + if (set_pmd_migration_entry(&pvmw, subpage)) { + ret = false; + page_vma_mapped_walk_done(&pvmw); + break; + } continue; } #endif -- cgit v1.2.3