diff options
Diffstat (limited to 'mm/rmap.c')
| -rw-r--r-- | mm/rmap.c | 61 |
1 files changed, 56 insertions, 5 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index 90f92c53476f..0d63e7ce35cc 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1088,6 +1088,7 @@ int pfn_mkclean_range(unsigned long pfn, unsigned long nr_pages, pgoff_t pgoff, void page_move_anon_rmap(struct page *page, struct vm_area_struct *vma) { struct anon_vma *anon_vma = vma->anon_vma; + struct page *subpage = page; page = compound_head(page); @@ -1101,6 +1102,7 @@ void page_move_anon_rmap(struct page *page, struct vm_area_struct *vma) * folio_test_anon()) will not see one without the other. */ WRITE_ONCE(page->mapping, (struct address_space *) anon_vma); + SetPageAnonExclusive(subpage); } /** @@ -1118,7 +1120,7 @@ static void __page_set_anon_rmap(struct page *page, BUG_ON(!anon_vma); if (PageAnon(page)) - return; + goto out; /* * If the page isn't exclusively mapped into this vma, @@ -1137,6 +1139,9 @@ static void __page_set_anon_rmap(struct page *page, anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; WRITE_ONCE(page->mapping, (struct address_space *) anon_vma); page->index = linear_page_index(vma, address); +out: + if (exclusive) + SetPageAnonExclusive(page); } /** @@ -1198,6 +1203,8 @@ void page_add_anon_rmap(struct page *page, } else { first = atomic_inc_and_test(&page->_mapcount); } + VM_BUG_ON_PAGE(!first && (flags & RMAP_EXCLUSIVE), page); + VM_BUG_ON_PAGE(!first && PageAnonExclusive(page), page); if (first) { int nr = compound ? thp_nr_pages(page) : 1; @@ -1459,7 +1466,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, address, 0); pte_t pteval; struct page *subpage; - bool ret = true; + bool anon_exclusive, ret = true; struct mmu_notifier_range range; enum ttu_flags flags = (enum ttu_flags)(long)arg; @@ -1515,6 +1522,8 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, subpage = folio_page(folio, pte_pfn(*pvmw.pte) - folio_pfn(folio)); address = pvmw.address; + anon_exclusive = folio_test_anon(folio) && + PageAnonExclusive(subpage); if (folio_test_hugetlb(folio) && !folio_test_anon(folio)) { /* @@ -1550,9 +1559,12 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, } } - /* Nuke the page table entry. */ + /* + * Nuke the page table entry. When having to clear + * PageAnonExclusive(), we always have to flush. + */ flush_cache_page(vma, address, pte_pfn(*pvmw.pte)); - if (should_defer_flush(mm, flags)) { + if (should_defer_flush(mm, flags) && !anon_exclusive) { /* * We clear the PTE but do not flush so potentially * a remote CPU could still be writing to the folio. @@ -1677,6 +1689,24 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, page_vma_mapped_walk_done(&pvmw); break; } + if (anon_exclusive && + page_try_share_anon_rmap(subpage)) { + swap_free(entry); + set_pte_at(mm, address, pvmw.pte, pteval); + ret = false; + page_vma_mapped_walk_done(&pvmw); + break; + } + /* + * Note: We *don't* remember yet if the page was mapped + * exclusively in the swap entry, so swapin code has + * to re-determine that manually and might detect the + * page as possibly shared, for example, if there are + * other references on the page or if the page is under + * writeback. We made sure that there are no GUP pins + * on the page that would rely on it, so for GUP pins + * this is fine. + */ if (list_empty(&mm->mmlist)) { spin_lock(&mmlist_lock); if (list_empty(&mm->mmlist)) @@ -1776,7 +1806,7 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, address, 0); pte_t pteval; struct page *subpage; - bool ret = true; + bool anon_exclusive, ret = true; struct mmu_notifier_range range; enum ttu_flags flags = (enum ttu_flags)(long)arg; @@ -1837,6 +1867,8 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, subpage = folio_page(folio, pte_pfn(*pvmw.pte) - folio_pfn(folio)); address = pvmw.address; + anon_exclusive = folio_test_anon(folio) && + PageAnonExclusive(subpage); if (folio_test_hugetlb(folio) && !folio_test_anon(folio)) { /* @@ -1888,6 +1920,9 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, swp_entry_t entry; pte_t swp_pte; + if (anon_exclusive) + BUG_ON(page_try_share_anon_rmap(subpage)); + /* * Store the pfn of the page in a special migration * pte. do_swap_page() will wait until the migration @@ -1896,6 +1931,8 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, entry = pte_to_swp_entry(pteval); if (is_writable_device_private_entry(entry)) entry = make_writable_migration_entry(pfn); + else if (anon_exclusive) + entry = make_readable_exclusive_migration_entry(pfn); else entry = make_readable_migration_entry(pfn); swp_pte = swp_entry_to_pte(entry); @@ -1960,6 +1997,15 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, page_vma_mapped_walk_done(&pvmw); break; } + VM_BUG_ON_PAGE(pte_write(pteval) && folio_test_anon(folio) && + !anon_exclusive, subpage); + if (anon_exclusive && + page_try_share_anon_rmap(subpage)) { + set_pte_at(mm, address, pvmw.pte, pteval); + ret = false; + page_vma_mapped_walk_done(&pvmw); + break; + } /* * Store the pfn of the page in a special migration @@ -1969,6 +2015,9 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, if (pte_write(pteval)) entry = make_writable_migration_entry( page_to_pfn(subpage)); + else if (anon_exclusive) + entry = make_readable_exclusive_migration_entry( + page_to_pfn(subpage)); else entry = make_readable_migration_entry( page_to_pfn(subpage)); @@ -2405,6 +2454,8 @@ void hugepage_add_anon_rmap(struct page *page, struct vm_area_struct *vma, BUG_ON(!anon_vma); /* address might be in next vma when migration races vma_adjust */ first = atomic_inc_and_test(compound_mapcount_ptr(page)); + VM_BUG_ON_PAGE(!first && (flags & RMAP_EXCLUSIVE), page); + VM_BUG_ON_PAGE(!first && PageAnonExclusive(page), page); if (first) __page_set_anon_rmap(page, vma, address, !!(flags & RMAP_EXCLUSIVE)); |