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Mon, 4 Dec 2023 14:22:59 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, David Hildenbrand , Andrew Morton , "Matthew Wilcox (Oracle)" , Hugh Dickins , Ryan Roberts , Yin Fengwei , Mike Kravetz , Muchun Song , Peter Xu Subject: [PATCH RFC 38/39] mm: convert page_try_share_anon_rmap() to folio_try_share_anon_rmap_[pte|pmd]() Date: Mon, 4 Dec 2023 15:21:45 +0100 Message-ID: <20231204142146.91437-39-david@redhat.com> In-Reply-To: <20231204142146.91437-1-david@redhat.com> References: <20231204142146.91437-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.4 X-Rspamd-Queue-Id: 95AC0100009 X-Rspam-User: X-Stat-Signature: 76d9x5dzctbn4wx1e7wfrzwxoxc5jnf9 X-Rspamd-Server: rspam01 X-HE-Tag: 1701699783-590066 X-HE-Meta: U2FsdGVkX19yFDBkl9eHkQuvYxMTIg9YJWpw76/cQKjXmscq8ZL7c4CsQaTEl66T7W2qXcYTM+ym0k1kNBzIlNodeCJgtp5onpw8jTTcww6Wvp0xXIqYZTgMFl1hW8Mj+yteYv2cd5PNegvoBMNoSS03YfvZ+9oHgrGwIgEQkUK2xsyRNPm8xBiJxzeIlR1q22XhSp+kIza3rpNCDA2JHUnZaSFH/M10ZcbDNVjEU0XOHu1yQPvE6mNAKnrsdLVpAQczm828o/RjxET63BPyrRsxTKZcLqHa+sYd+qn/lTODNiaYVrNlk7eRQqCXDmTA6w9QDNQljlFzjbgkkXkqrqH++0PcXNFx6dxTDg6iFBnQTVYdNpvvuFhY238AlhpgQI+5YMMZR/gXD8ih1il4w5VaQmIEkn27uH+gSgmfBlmC48I5+9B7FwPa0H/CN0oyDuESFgxFLGrquO6VVDLFMwb2/Og8ehY1rRL35RCRcz2p3oCjYKsSGYa/askZL2tvh9WS/vfehkFWlxF28pOb/ftQnChe3UWMuQuHR3/Y7IsPIHjYf8/XXz266r8xoD1EJQ5DVCcYlzCwjMgaApbPdYTjE6JIhiN7mOdNJifMB970XwkUmsuPKBQdnvvtK1+Qfp7kXWJvJzhcrEpRMoh/frkhC6ES/57F94LS7YYq0vPVHL+5PTmPRXwTShyYgpOnElcooFbTcxlL9ygvPqEG/g8KFYLIqqBg9LNJ87BMtpeAtrWTTCopSVDWXhXas6sckDXEkwpmQ4xUQK2VCeHwha+LXqL6ToMwfF5fnRa7AElhl8P1vJHVUirMSndNo0nbSWCAVehpyB6kUM/5hWAW/R/XSr95VPmU+Kx662BHix8+1HbgJ3C2Yb+jaHhL1jbennA5Veeh8ZAPIbsQPytZNuLhBhtU9R6Y4EU0z2RviBP1+1qfR5Mbk4W8ApFFsp6hGLI3J/uY+/GYd5/Z6np f5i5Hehk 02DR83h6XmQ8uwA62BYktQstdVhi9g6Kc2qyxQvmnC+LPNmx0kqKrCOTGhS1+Ropd1bCvhOL16cmukRjT2T2d3hZ5nBlz7qi5omKW5SWJGfDSoynQl3KfebYoIVmH7Sb0u/rMQiQwNunjsXXySci1BGUvyL+JEnQ9oLCGocDftS5E2XQiBRf2oQfRNZZWcpAcMD8PazvechX6XQwoFqfbqe8wbveMtnenNxk7 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Let's convert it like we converted all the other rmap functions. Don't introduce folio_try_share_anon_rmap_ptes() for now, as we don't have a user that wants rmap batching in sight. Pretty easy to add later. All users are easy to convert -- only ksm.c doesn't use folios yet but that is left for future work -- so let's just do it in a single shot. While at it, turn the BUG_ON into a WARN_ON_ONCE. Note that page_try_share_anon_rmap() so far didn't care about pte/pmd mappings (no compound parameter). We're changing that so we can perform better sanity checks and make the code actually more readable/consistent. For example, __folio_rmap_sanity_checks() will make sure that a PMD range actually falls completely into the folio. Signed-off-by: David Hildenbrand --- include/linux/rmap.h | 98 ++++++++++++++++++++++++++++++++------------ mm/gup.c | 2 +- mm/huge_memory.c | 9 ++-- mm/internal.h | 4 +- mm/ksm.c | 5 ++- mm/migrate_device.c | 2 +- mm/rmap.c | 9 ++-- 7 files changed, 89 insertions(+), 40 deletions(-) diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 3c1df8e020188..ab3ea4583d502 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -267,14 +267,14 @@ static inline int hugetlb_try_dup_anon_rmap(struct folio *folio, return 0; } -/* See page_try_share_anon_rmap() */ +/* 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); - /* See page_try_share_anon_rmap() */ + /* See folio_try_share_anon_rmap_*() */ if (IS_ENABLED(CONFIG_HAVE_FAST_GUP)) smp_mb(); @@ -282,7 +282,7 @@ static inline int hugetlb_try_share_anon_rmap(struct folio *folio) return -EBUSY; ClearPageAnonExclusive(&folio->page); - /* See page_try_share_anon_rmap() */ + /* See folio_try_share_anon_rmap_*() */ if (IS_ENABLED(CONFIG_HAVE_FAST_GUP)) smp_mb__after_atomic(); return 0; @@ -463,30 +463,15 @@ static inline int folio_try_dup_anon_rmap_pmd(struct folio *folio, #endif } -/** - * 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 - * - * The caller needs to hold the PT lock and has to have the page table entry - * cleared/invalidated. - * - * This is similar to folio_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 folio_remove_rmap_*(). - * - * 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. - * - * Returns 0 if marking the page possibly shared succeeded. Returns -EBUSY - * otherwise. - */ -static inline int page_try_share_anon_rmap(struct page *page) +static inline int __folio_try_share_anon_rmap(struct folio *folio, + struct page *page, unsigned int nr_pages, enum rmap_mode mode) { - VM_BUG_ON_PAGE(!PageAnon(page) || !PageAnonExclusive(page), page); + VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio); + VM_WARN_ON_FOLIO(!PageAnonExclusive(page), folio); + __folio_rmap_sanity_checks(folio, page, nr_pages, mode); - /* device private pages cannot get pinned via GUP. */ - if (unlikely(is_device_private_page(page))) { + /* device private folios cannot get pinned via GUP. */ + if (unlikely(folio_is_device_private(folio))) { ClearPageAnonExclusive(page); return 0; } @@ -537,7 +522,7 @@ 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); @@ -550,6 +535,67 @@ 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_MODE_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_MODE_PMD); +#else + WARN_ON_ONCE(true); +#endif +} + /* * Called from mm/vmscan.c to handle paging out */ diff --git a/mm/gup.c b/mm/gup.c index 231711efa390d..49f32411c68da 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -177,7 +177,7 @@ struct folio *try_grab_folio(struct page *page, int refs, unsigned int flags) /* * Adjust the pincount before re-checking the PTE for changes. * This is essentially a smp_mb() and is paired with a memory - * barrier in page_try_share_anon_rmap(). + * barrier in folio_try_share_anon_rmap_*(). */ smp_mb__after_atomic(); diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 138e1e62790be..ebbf5ee6192e7 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2224,10 +2224,11 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, * In case we cannot clear PageAnonExclusive(), split the PMD * only and let try_to_migrate_one() fail later. * - * See page_try_share_anon_rmap(): invalidate PMD first. + * See folio_try_share_anon_rmap_pmd(): invalidate PMD first. */ anon_exclusive = PageAnonExclusive(page); - if (freeze && anon_exclusive && page_try_share_anon_rmap(page)) + if (freeze && anon_exclusive && + folio_try_share_anon_rmap_pmd(folio, page)) freeze = false; if (!freeze) { rmap_t rmap_flags = RMAP_NONE; @@ -3253,9 +3254,9 @@ int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); pmdval = pmdp_invalidate(vma, address, pvmw->pmd); - /* See page_try_share_anon_rmap(): invalidate PMD first. */ + /* See folio_try_share_anon_rmap_pmd(): invalidate PMD first. */ anon_exclusive = folio_test_anon(folio) && PageAnonExclusive(page); - if (anon_exclusive && page_try_share_anon_rmap(page)) { + if (anon_exclusive && folio_try_share_anon_rmap_pmd(folio, page)) { set_pmd_at(mm, address, pvmw->pmd, pmdval); return -EBUSY; } diff --git a/mm/internal.h b/mm/internal.h index 43dca750c5afc..b9b630717b9b2 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -1047,7 +1047,7 @@ enum { * * Ordinary GUP: Using the PT lock * * GUP-fast and fork(): mm->write_protect_seq * * GUP-fast and KSM or temporary unmapping (swap, migration): see - * page_try_share_anon_rmap() + * folio_try_share_anon_rmap_*() * * Must be called with the (sub)page that's actually referenced via the * page table entry, which might not necessarily be the head page for a @@ -1090,7 +1090,7 @@ static inline bool gup_must_unshare(struct vm_area_struct *vma, return is_cow_mapping(vma->vm_flags); } - /* Paired with a memory barrier in page_try_share_anon_rmap(). */ + /* Paired with a memory barrier in folio_try_share_anon_rmap_*(). */ if (IS_ENABLED(CONFIG_HAVE_FAST_GUP)) smp_rmb(); diff --git a/mm/ksm.c b/mm/ksm.c index c23aed4f1a344..51f2d989be2be 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -1161,8 +1161,9 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page, goto out_unlock; } - /* See page_try_share_anon_rmap(): clear PTE first. */ - if (anon_exclusive && page_try_share_anon_rmap(page)) { + /* See folio_try_share_anon_rmap_pte(): clear PTE first. */ + if (anon_exclusive && + folio_try_share_anon_rmap_pte(page_folio(page), page)) { set_pte_at(mm, pvmw.address, pvmw.pte, entry); goto out_unlock; } diff --git a/mm/migrate_device.c b/mm/migrate_device.c index c51c99151ebb5..9d0c1ad737225 100644 --- a/mm/migrate_device.c +++ b/mm/migrate_device.c @@ -202,7 +202,7 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp, if (anon_exclusive) { pte = ptep_clear_flush(vma, addr, ptep); - if (page_try_share_anon_rmap(page)) { + if (folio_try_share_anon_rmap_pte(folio, page)) { set_pte_at(mm, addr, ptep, pte); folio_unlock(folio); folio_put(folio); diff --git a/mm/rmap.c b/mm/rmap.c index 8e86024953c03..7bb3a174efc8d 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1817,9 +1817,9 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, break; } - /* See page_try_share_anon_rmap(): clear PTE first. */ + /* See folio_try_share_anon_rmap(): clear PTE first. */ if (anon_exclusive && - page_try_share_anon_rmap(subpage)) { + folio_try_share_anon_rmap_pte(folio, subpage)) { swap_free(entry); set_pte_at(mm, address, pvmw.pte, pteval); ret = false; @@ -2093,7 +2093,8 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, pte_t swp_pte; if (anon_exclusive) - BUG_ON(page_try_share_anon_rmap(subpage)); + WARN_ON_ONCE(folio_try_share_anon_rmap_pte(folio, + subpage)); /* * Store the pfn of the page in a special migration @@ -2175,7 +2176,7 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, break; } } else if (anon_exclusive && - page_try_share_anon_rmap(page)) { + folio_try_share_anon_rmap_pte(folio, subpage)) { set_pte_at(mm, address, pvmw.pte, pteval); ret = false; page_vma_mapped_walk_done(&pvmw);