From: David Hildenbrand david@redhat.com
mainline inclusion from mainline-v6.8-rc1 commit 61d90309b7156d54c5d358cb5d8bf55b33d233d2 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I9CESE CVE: NA
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The last user of page_needs_cow_for_dma() and __page_dup_rmap() are gone, remove them.
Add folio_try_dup_anon_rmap_ptes() right away, we want to perform rmap baching during fork() soon.
Link: https://lkml.kernel.org/r/20231220224504.646757-35-david@redhat.com Signed-off-by: David Hildenbrand david@redhat.com Cc: Hugh Dickins hughd@google.com Cc: Matthew Wilcox (Oracle) willy@infradead.org Cc: Muchun Song muchun.song@linux.dev Cc: Muchun Song songmuchun@bytedance.com Cc: Peter Xu peterx@redhat.com Cc: Ryan Roberts ryan.roberts@arm.com Cc: Yin Fengwei fengwei.yin@intel.com Signed-off-by: Andrew Morton akpm@linux-foundation.org (cherry picked from commit 61d90309b7156d54c5d358cb5d8bf55b33d233d2) Signed-off-by: Kefeng Wang wangkefeng.wang@huawei.com --- include/linux/mm.h | 6 -- include/linux/rmap.h | 150 ++++++++++++++++++++++++++++++------------- 2 files changed, 106 insertions(+), 50 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h index 3f2fe3b85dc0..3452aa356a71 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1991,12 +1991,6 @@ static inline bool folio_needs_cow_for_dma(struct vm_area_struct *vma, return folio_maybe_dma_pinned(folio); }
-static inline bool page_needs_cow_for_dma(struct vm_area_struct *vma, - struct page *page) -{ - return folio_needs_cow_for_dma(vma, page_folio(page)); -} - /** * is_zero_page - Query if a page is a zero page * @page: The page to query diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 8f369fb3ed71..697cce4b5a93 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -359,68 +359,130 @@ static inline void folio_dup_file_rmap_pmd(struct folio *folio, #endif }
-static inline void __page_dup_rmap(struct page *page, bool compound) +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) { - VM_WARN_ON(folio_test_hugetlb(page_folio(page))); + bool maybe_pinned; + int i; + + VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio); + __folio_rmap_sanity_checks(folio, page, nr_pages, level);
- if (compound) { - struct folio *folio = (struct folio *)page; + /* + * 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. + */ + maybe_pinned = likely(!folio_is_device_private(folio)) && + unlikely(folio_needs_cow_for_dma(src_vma, folio));
- VM_BUG_ON_PAGE(compound && !PageHead(page), page); + /* + * 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. + */ + 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); - } else { - atomic_inc(&page->_mapcount); + break; } + return 0; }
/** - * 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_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 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 and the + * vma->vma_mm->write_protect_seq. + * + * 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. + * + * 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 duplicating the mappings succeeded. Returns -EBUSY otherwise. + */ +static inline int folio_try_dup_anon_rmap_ptes(struct folio *folio, + struct page *page, int nr_pages, struct vm_area_struct *src_vma) +{ + 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) + +/** + * 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) * - * 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 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 inline int page_try_dup_anon_rmap(struct page *page, bool compound, struct vm_area_struct *vma) { - VM_BUG_ON_PAGE(!PageAnon(page), page); - - /* - * No need to check+clear for already shared pages, including KSM - * pages. - */ - if (!PageAnonExclusive(page)) - goto dup; - - /* - * 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 - * future on write faults. - */ - if (likely(!is_device_private_page(page)) && - unlikely(page_needs_cow_for_dma(vma, page))) - return -EBUSY; + struct folio *folio = page_folio(page);
- ClearPageAnonExclusive(page); - /* - * It's okay to share the anon page between both processes, mapping - * the page R/O into both processes. - */ -dup: - __page_dup_rmap(page, compound); - return 0; + if (likely(!compound)) + return folio_try_dup_anon_rmap_pte(folio, page, vma); + return folio_try_dup_anon_rmap_pmd(folio, page, vma); }
/**