diff options
Diffstat (limited to 'include/linux/rmap.h')
| -rw-r--r-- | include/linux/rmap.h | 411 |
1 files changed, 334 insertions, 77 deletions
diff --git a/include/linux/rmap.h b/include/linux/rmap.h index b26fe858fd44..b7944a833668 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -121,6 +121,11 @@ static inline void anon_vma_lock_write(struct anon_vma *anon_vma) down_write(&anon_vma->root->rwsem); } +static inline int anon_vma_trylock_write(struct anon_vma *anon_vma) +{ + return down_write_trylock(&anon_vma->root->rwsem); +} + static inline void anon_vma_unlock_write(struct anon_vma *anon_vma) { up_write(&anon_vma->root->rwsem); @@ -172,133 +177,323 @@ struct anon_vma *folio_get_anon_vma(struct folio *folio); typedef int __bitwise rmap_t; /* - * No special request: if the page is a subpage of a compound page, it is - * mapped via a PTE. The mapped (sub)page is possibly shared between processes. + * No special request: A mapped anonymous (sub)page is possibly shared between + * processes. */ #define RMAP_NONE ((__force rmap_t)0) -/* The (sub)page is exclusive to a single process. */ +/* The anonymous (sub)page is exclusive to a single process. */ #define RMAP_EXCLUSIVE ((__force rmap_t)BIT(0)) /* - * The compound page is not mapped via PTEs, but instead via a single PMD and - * should be accounted accordingly. + * Internally, we're using an enum to specify the granularity. We make the + * compiler emit specialized code for each granularity. */ -#define RMAP_COMPOUND ((__force rmap_t)BIT(1)) +enum rmap_level { + RMAP_LEVEL_PTE = 0, + RMAP_LEVEL_PMD, +}; + +static inline void __folio_rmap_sanity_checks(struct folio *folio, + struct page *page, int nr_pages, enum rmap_level level) +{ + /* hugetlb folios are handled separately. */ + VM_WARN_ON_FOLIO(folio_test_hugetlb(folio), folio); + + /* + * TODO: we get driver-allocated folios that have nothing to do with + * the rmap using vm_insert_page(); therefore, we cannot assume that + * folio_test_large_rmappable() holds for large folios. We should + * handle any desired mapcount+stats accounting for these folios in + * VM_MIXEDMAP VMAs separately, and then sanity-check here that + * we really only get rmappable folios. + */ + + VM_WARN_ON_ONCE(nr_pages <= 0); + VM_WARN_ON_FOLIO(page_folio(page) != folio, folio); + VM_WARN_ON_FOLIO(page_folio(page + nr_pages - 1) != folio, folio); + + switch (level) { + case RMAP_LEVEL_PTE: + break; + case RMAP_LEVEL_PMD: + /* + * We don't support folios larger than a single PMD yet. So + * when RMAP_LEVEL_PMD is set, we assume that we are creating + * a single "entire" mapping of the folio. + */ + VM_WARN_ON_FOLIO(folio_nr_pages(folio) != HPAGE_PMD_NR, folio); + VM_WARN_ON_FOLIO(nr_pages != HPAGE_PMD_NR, folio); + break; + default: + VM_WARN_ON_ONCE(true); + } +} /* * rmap interfaces called when adding or removing pte of page */ void folio_move_anon_rmap(struct folio *, struct vm_area_struct *); -void page_add_anon_rmap(struct page *, struct vm_area_struct *, - unsigned long address, rmap_t flags); -void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, - unsigned long address); +void folio_add_anon_rmap_ptes(struct folio *, struct page *, int nr_pages, + struct vm_area_struct *, unsigned long address, rmap_t flags); +#define folio_add_anon_rmap_pte(folio, page, vma, address, flags) \ + folio_add_anon_rmap_ptes(folio, page, 1, vma, address, flags) +void folio_add_anon_rmap_pmd(struct folio *, struct page *, + struct vm_area_struct *, unsigned long address, rmap_t flags); void folio_add_new_anon_rmap(struct folio *, struct vm_area_struct *, unsigned long address); -void page_add_file_rmap(struct page *, struct vm_area_struct *, - bool compound); -void folio_add_file_rmap_range(struct folio *, struct page *, unsigned int nr, - struct vm_area_struct *, bool compound); -void page_remove_rmap(struct page *, struct vm_area_struct *, - bool compound); - -void hugepage_add_anon_rmap(struct folio *, struct vm_area_struct *, +void folio_add_file_rmap_ptes(struct folio *, struct page *, int nr_pages, + struct vm_area_struct *); +#define folio_add_file_rmap_pte(folio, page, vma) \ + folio_add_file_rmap_ptes(folio, page, 1, vma) +void folio_add_file_rmap_pmd(struct folio *, struct page *, + struct vm_area_struct *); +void folio_remove_rmap_ptes(struct folio *, struct page *, int nr_pages, + struct vm_area_struct *); +#define folio_remove_rmap_pte(folio, page, vma) \ + folio_remove_rmap_ptes(folio, page, 1, vma) +void folio_remove_rmap_pmd(struct folio *, struct page *, + struct vm_area_struct *); + +void hugetlb_add_anon_rmap(struct folio *, struct vm_area_struct *, unsigned long address, rmap_t flags); -void hugepage_add_new_anon_rmap(struct folio *, struct vm_area_struct *, +void hugetlb_add_new_anon_rmap(struct folio *, struct vm_area_struct *, unsigned long address); -static inline void __page_dup_rmap(struct page *page, bool compound) +/* See folio_try_dup_anon_rmap_*() */ +static inline int hugetlb_try_dup_anon_rmap(struct folio *folio, + struct vm_area_struct *vma) { - if (compound) { - struct folio *folio = (struct folio *)page; + VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio); + VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio); - VM_BUG_ON_PAGE(compound && !PageHead(page), page); - atomic_inc(&folio->_entire_mapcount); - } else { - atomic_inc(&page->_mapcount); + if (PageAnonExclusive(&folio->page)) { + if (unlikely(folio_needs_cow_for_dma(vma, folio))) + return -EBUSY; + ClearPageAnonExclusive(&folio->page); } + atomic_inc(&folio->_entire_mapcount); + return 0; +} + +/* See folio_try_share_anon_rmap_*() */ +static inline int hugetlb_try_share_anon_rmap(struct folio *folio) +{ + VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio); + VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio); + VM_WARN_ON_FOLIO(!PageAnonExclusive(&folio->page), folio); + + /* Paired with the memory barrier in try_grab_folio(). */ + if (IS_ENABLED(CONFIG_HAVE_FAST_GUP)) + smp_mb(); + + if (unlikely(folio_maybe_dma_pinned(folio))) + return -EBUSY; + ClearPageAnonExclusive(&folio->page); + + /* + * This is conceptually a smp_wmb() paired with the smp_rmb() in + * gup_must_unshare(). + */ + if (IS_ENABLED(CONFIG_HAVE_FAST_GUP)) + smp_mb__after_atomic(); + return 0; +} + +static inline void hugetlb_add_file_rmap(struct folio *folio) +{ + VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio); + VM_WARN_ON_FOLIO(folio_test_anon(folio), folio); + + atomic_inc(&folio->_entire_mapcount); +} + +static inline void hugetlb_remove_rmap(struct folio *folio) +{ + VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio); + + atomic_dec(&folio->_entire_mapcount); } -static inline void page_dup_file_rmap(struct page *page, bool compound) +static __always_inline void __folio_dup_file_rmap(struct folio *folio, + struct page *page, int nr_pages, enum rmap_level level) { - __page_dup_rmap(page, compound); + __folio_rmap_sanity_checks(folio, page, nr_pages, level); + + switch (level) { + case RMAP_LEVEL_PTE: + do { + atomic_inc(&page->_mapcount); + } while (page++, --nr_pages > 0); + break; + case RMAP_LEVEL_PMD: + atomic_inc(&folio->_entire_mapcount); + break; + } } /** - * page_try_dup_anon_rmap - try duplicating a mapping of an already mapped - * anonymous page - * @page: the page to duplicate the mapping for - * @compound: the page is mapped as compound or as a small page - * @vma: the source vma + * folio_dup_file_rmap_ptes - duplicate PTE mappings of a page range of a folio + * @folio: The folio to duplicate the mappings of + * @page: The first page to duplicate the mappings of + * @nr_pages: The number of pages of which the mapping will be duplicated * - * The caller needs to hold the PT lock and the vma->vma_mm->write_protect_seq. + * The page range of the folio is defined by [page, page + nr_pages) * - * Duplicating the mapping can only fail if the page may be pinned; device - * private pages cannot get pinned and consequently this function cannot fail. + * The caller needs to hold the page table lock. + */ +static inline void folio_dup_file_rmap_ptes(struct folio *folio, + struct page *page, int nr_pages) +{ + __folio_dup_file_rmap(folio, page, nr_pages, RMAP_LEVEL_PTE); +} +#define folio_dup_file_rmap_pte(folio, page) \ + folio_dup_file_rmap_ptes(folio, page, 1) + +/** + * folio_dup_file_rmap_pmd - duplicate a PMD mapping of a page range of a folio + * @folio: The folio to duplicate the mapping of + * @page: The first page to duplicate the mapping of * - * If duplicating the mapping succeeds, the page has to be mapped R/O into - * the parent and the child. It must *not* get mapped writable after this call. + * The page range of the folio is defined by [page, page + HPAGE_PMD_NR) * - * Returns 0 if duplicating the mapping succeeded. Returns -EBUSY otherwise. + * The caller needs to hold the page table lock. */ -static inline int page_try_dup_anon_rmap(struct page *page, bool compound, - struct vm_area_struct *vma) +static inline void folio_dup_file_rmap_pmd(struct folio *folio, + struct page *page) { - VM_BUG_ON_PAGE(!PageAnon(page), page); +#ifdef CONFIG_TRANSPARENT_HUGEPAGE + __folio_dup_file_rmap(folio, page, HPAGE_PMD_NR, RMAP_LEVEL_PTE); +#else + WARN_ON_ONCE(true); +#endif +} - /* - * No need to check+clear for already shared pages, including KSM - * pages. - */ - if (!PageAnonExclusive(page)) - goto dup; +static __always_inline int __folio_try_dup_anon_rmap(struct folio *folio, + struct page *page, int nr_pages, struct vm_area_struct *src_vma, + enum rmap_level level) +{ + bool maybe_pinned; + int i; + + VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio); + __folio_rmap_sanity_checks(folio, page, nr_pages, level); /* - * If this page may have been pinned by the parent process, - * don't allow to duplicate the mapping but instead require to e.g., - * copy the page immediately for the child so that we'll always - * guarantee the pinned page won't be randomly replaced in the + * If this folio may have been pinned by the parent process, + * don't allow to duplicate the mappings but instead require to e.g., + * copy the subpage immediately for the child so that we'll always + * guarantee the pinned folio won't be randomly replaced in the * future on write faults. */ - if (likely(!is_device_private_page(page) && - unlikely(page_needs_cow_for_dma(vma, page)))) - return -EBUSY; + maybe_pinned = likely(!folio_is_device_private(folio)) && + unlikely(folio_needs_cow_for_dma(src_vma, folio)); - ClearPageAnonExclusive(page); /* - * It's okay to share the anon page between both processes, mapping - * the page R/O into both processes. + * No need to check+clear for already shared PTEs/PMDs of the + * folio. But if any page is PageAnonExclusive, we must fallback to + * copying if the folio maybe pinned. */ -dup: - __page_dup_rmap(page, compound); + switch (level) { + case RMAP_LEVEL_PTE: + if (unlikely(maybe_pinned)) { + for (i = 0; i < nr_pages; i++) + if (PageAnonExclusive(page + i)) + return -EBUSY; + } + do { + if (PageAnonExclusive(page)) + ClearPageAnonExclusive(page); + atomic_inc(&page->_mapcount); + } while (page++, --nr_pages > 0); + break; + case RMAP_LEVEL_PMD: + if (PageAnonExclusive(page)) { + if (unlikely(maybe_pinned)) + return -EBUSY; + ClearPageAnonExclusive(page); + } + atomic_inc(&folio->_entire_mapcount); + break; + } return 0; } /** - * page_try_share_anon_rmap - try marking an exclusive anonymous page possibly - * shared to prepare for KSM or temporary unmapping - * @page: the exclusive anonymous page to try marking possibly shared + * folio_try_dup_anon_rmap_ptes - try duplicating PTE mappings of a page range + * of a folio + * @folio: The folio to duplicate the mappings of + * @page: The first page to duplicate the mappings of + * @nr_pages: The number of pages of which the mapping will be duplicated + * @src_vma: The vm area from which the mappings are duplicated + * + * The page range of the folio is defined by [page, page + nr_pages) * - * The caller needs to hold the PT lock and has to have the page table entry - * cleared/invalidated. + * The caller needs to hold the page table lock and the + * vma->vma_mm->write_protect_seq. * - * This is similar to page_try_dup_anon_rmap(), however, not used during fork() - * to duplicate a mapping, but instead to prepare for KSM or temporarily - * unmapping a page (swap, migration) via page_remove_rmap(). + * Duplicating the mappings can only fail if the folio may be pinned; device + * private folios cannot get pinned and consequently this function cannot fail + * for them. * - * Marking the page shared can only fail if the page may be pinned; device - * private pages cannot get pinned and consequently this function cannot fail. + * If duplicating the mappings succeeded, the duplicated PTEs have to be R/O in + * the parent and the child. They must *not* be writable after this call + * succeeded. * - * Returns 0 if marking the page possibly shared succeeded. Returns -EBUSY - * otherwise. + * Returns 0 if duplicating the mappings succeeded. Returns -EBUSY otherwise. */ -static inline int page_try_share_anon_rmap(struct page *page) +static inline int folio_try_dup_anon_rmap_ptes(struct folio *folio, + struct page *page, int nr_pages, struct vm_area_struct *src_vma) { - VM_BUG_ON_PAGE(!PageAnon(page) || !PageAnonExclusive(page), page); + return __folio_try_dup_anon_rmap(folio, page, nr_pages, src_vma, + RMAP_LEVEL_PTE); +} +#define folio_try_dup_anon_rmap_pte(folio, page, vma) \ + folio_try_dup_anon_rmap_ptes(folio, page, 1, vma) - /* device private pages cannot get pinned via GUP. */ - if (unlikely(is_device_private_page(page))) { +/** + * folio_try_dup_anon_rmap_pmd - try duplicating a PMD mapping of a page range + * of a folio + * @folio: The folio to duplicate the mapping of + * @page: The first page to duplicate the mapping of + * @src_vma: The vm area from which the mapping is duplicated + * + * The page range of the folio is defined by [page, page + HPAGE_PMD_NR) + * + * The caller needs to hold the page table lock and the + * vma->vma_mm->write_protect_seq. + * + * Duplicating the mapping can only fail if the folio may be pinned; device + * private folios cannot get pinned and consequently this function cannot fail + * for them. + * + * If duplicating the mapping succeeds, the duplicated PMD has to be R/O in + * the parent and the child. They must *not* be writable after this call + * succeeded. + * + * Returns 0 if duplicating the mapping succeeded. Returns -EBUSY otherwise. + */ +static inline int folio_try_dup_anon_rmap_pmd(struct folio *folio, + struct page *page, struct vm_area_struct *src_vma) +{ +#ifdef CONFIG_TRANSPARENT_HUGEPAGE + return __folio_try_dup_anon_rmap(folio, page, HPAGE_PMD_NR, src_vma, + RMAP_LEVEL_PMD); +#else + WARN_ON_ONCE(true); + return -EBUSY; +#endif +} + +static __always_inline int __folio_try_share_anon_rmap(struct folio *folio, + struct page *page, int nr_pages, enum rmap_level level) +{ + VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio); + VM_WARN_ON_FOLIO(!PageAnonExclusive(page), folio); + __folio_rmap_sanity_checks(folio, page, nr_pages, level); + + /* device private folios cannot get pinned via GUP. */ + if (unlikely(folio_is_device_private(folio))) { ClearPageAnonExclusive(page); return 0; } @@ -349,7 +544,7 @@ static inline int page_try_share_anon_rmap(struct page *page) if (IS_ENABLED(CONFIG_HAVE_FAST_GUP)) smp_mb(); - if (unlikely(page_maybe_dma_pinned(page))) + if (unlikely(folio_maybe_dma_pinned(folio))) return -EBUSY; ClearPageAnonExclusive(page); @@ -362,6 +557,68 @@ static inline int page_try_share_anon_rmap(struct page *page) return 0; } +/** + * folio_try_share_anon_rmap_pte - try marking an exclusive anonymous page + * mapped by a PTE possibly shared to prepare + * for KSM or temporary unmapping + * @folio: The folio to share a mapping of + * @page: The mapped exclusive page + * + * The caller needs to hold the page table lock and has to have the page table + * entries cleared/invalidated. + * + * This is similar to folio_try_dup_anon_rmap_pte(), however, not used during + * fork() to duplicate mappings, but instead to prepare for KSM or temporarily + * unmapping parts of a folio (swap, migration) via folio_remove_rmap_pte(). + * + * Marking the mapped page shared can only fail if the folio maybe pinned; + * device private folios cannot get pinned and consequently this function cannot + * fail. + * + * Returns 0 if marking the mapped page possibly shared succeeded. Returns + * -EBUSY otherwise. + */ +static inline int folio_try_share_anon_rmap_pte(struct folio *folio, + struct page *page) +{ + return __folio_try_share_anon_rmap(folio, page, 1, RMAP_LEVEL_PTE); +} + +/** + * folio_try_share_anon_rmap_pmd - try marking an exclusive anonymous page + * range mapped by a PMD possibly shared to + * prepare for temporary unmapping + * @folio: The folio to share the mapping of + * @page: The first page to share the mapping of + * + * The page range of the folio is defined by [page, page + HPAGE_PMD_NR) + * + * The caller needs to hold the page table lock and has to have the page table + * entries cleared/invalidated. + * + * This is similar to folio_try_dup_anon_rmap_pmd(), however, not used during + * fork() to duplicate a mapping, but instead to prepare for temporarily + * unmapping parts of a folio (swap, migration) via folio_remove_rmap_pmd(). + * + * Marking the mapped pages shared can only fail if the folio maybe pinned; + * device private folios cannot get pinned and consequently this function cannot + * fail. + * + * Returns 0 if marking the mapped pages possibly shared succeeded. Returns + * -EBUSY otherwise. + */ +static inline int folio_try_share_anon_rmap_pmd(struct folio *folio, + struct page *page) +{ +#ifdef CONFIG_TRANSPARENT_HUGEPAGE + return __folio_try_share_anon_rmap(folio, page, HPAGE_PMD_NR, + RMAP_LEVEL_PMD); +#else + WARN_ON_ONCE(true); + return -EBUSY; +#endif +} + /* * Called from mm/vmscan.c to handle paging out */ |