From 2aff7a4755bed2870ee23b75bc88cdc8d76cdd03 Mon Sep 17 00:00:00 2001 From: "Matthew Wilcox (Oracle)" Date: Thu, 3 Feb 2022 11:40:17 -0500 Subject: [PATCH] mm: Convert page_vma_mapped_walk to work on PFNs page_mapped_in_vma() really just wants to walk one page, but as the code stands, if passed the head page of a compound page, it will walk every page in the compound page. Extract pfn/nr_pages/pgoff from the struct page early, so they can be overridden by page_mapped_in_vma(). Signed-off-by: Matthew Wilcox (Oracle) --- include/linux/hugetlb.h | 5 ++++ include/linux/rmap.h | 17 ++++++++---- mm/internal.h | 15 ++++++----- mm/migrate.c | 5 ++-- mm/page_vma_mapped.c | 58 ++++++++++++++++++----------------------- mm/rmap.c | 8 +++--- 6 files changed, 58 insertions(+), 50 deletions(-) diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index d1897a69c540..6ba2f8e74fbb 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -970,6 +970,11 @@ static inline struct hstate *page_hstate(struct page *page) return NULL; } +static inline struct hstate *size_to_hstate(unsigned long size) +{ + return NULL; +} + static inline unsigned long huge_page_size(struct hstate *h) { return PAGE_SIZE; diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 0d894a2bfaa1..0c838ba1a8ee 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -11,6 +11,7 @@ #include #include #include +#include /* * The anon_vma heads a list of private "related" vmas, to scan if @@ -201,11 +202,13 @@ int make_device_exclusive_range(struct mm_struct *mm, unsigned long start, /* Avoid racy checks */ #define PVMW_SYNC (1 << 0) -/* Look for migarion entries rather than present PTEs */ +/* Look for migration entries rather than present PTEs */ #define PVMW_MIGRATION (1 << 1) struct page_vma_mapped_walk { - struct page *page; + unsigned long pfn; + unsigned long nr_pages; + pgoff_t pgoff; struct vm_area_struct *vma; unsigned long address; pmd_t *pmd; @@ -216,7 +219,9 @@ struct page_vma_mapped_walk { #define DEFINE_PAGE_VMA_WALK(name, _page, _vma, _address, _flags) \ struct page_vma_mapped_walk name = { \ - .page = _page, \ + .pfn = page_to_pfn(_page), \ + .nr_pages = compound_nr(page), \ + .pgoff = page_to_pgoff(page), \ .vma = _vma, \ .address = _address, \ .flags = _flags, \ @@ -224,7 +229,9 @@ struct page_vma_mapped_walk { #define DEFINE_FOLIO_VMA_WALK(name, _folio, _vma, _address, _flags) \ struct page_vma_mapped_walk name = { \ - .page = &_folio->page, \ + .pfn = folio_pfn(_folio), \ + .nr_pages = folio_nr_pages(_folio), \ + .pgoff = folio_pgoff(_folio), \ .vma = _vma, \ .address = _address, \ .flags = _flags, \ @@ -233,7 +240,7 @@ struct page_vma_mapped_walk { static inline void page_vma_mapped_walk_done(struct page_vma_mapped_walk *pvmw) { /* HugeTLB pte is set to the relevant page table entry without pte_mapped. */ - if (pvmw->pte && !PageHuge(pvmw->page)) + if (pvmw->pte && !is_vm_hugetlb_page(pvmw->vma)) pte_unmap(pvmw->pte); if (pvmw->ptl) spin_unlock(pvmw->ptl); diff --git a/mm/internal.h b/mm/internal.h index 6047268076e7..3b652444f070 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -10,6 +10,7 @@ #include #include #include +#include #include struct folio_batch; @@ -475,18 +476,20 @@ vma_address(struct page *page, struct vm_area_struct *vma) } /* - * Then at what user virtual address will none of the page be found in vma? + * Then at what user virtual address will none of the range be found in vma? * Assumes that vma_address() already returned a good starting address. - * If page is a compound head, the entire compound page is considered. */ -static inline unsigned long -vma_address_end(struct page *page, struct vm_area_struct *vma) +static inline unsigned long vma_address_end(struct page_vma_mapped_walk *pvmw) { + struct vm_area_struct *vma = pvmw->vma; pgoff_t pgoff; unsigned long address; - VM_BUG_ON_PAGE(PageKsm(page), page); /* KSM page->index unusable */ - pgoff = page_to_pgoff(page) + compound_nr(page); + /* Common case, plus ->pgoff is invalid for KSM */ + if (pvmw->nr_pages == 1) + return pvmw->address + PAGE_SIZE; + + pgoff = pvmw->pgoff + pvmw->nr_pages; address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); /* Check for address beyond vma (or wrapped through 0?) */ if (address < vma->vm_start || address > vma->vm_end) diff --git a/mm/migrate.c b/mm/migrate.c index 71f92e8ed934..358bc311caaa 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -174,7 +174,8 @@ void putback_movable_pages(struct list_head *l) static bool remove_migration_pte(struct page *page, struct vm_area_struct *vma, unsigned long addr, void *old) { - DEFINE_PAGE_VMA_WALK(pvmw, old, vma, addr, PVMW_SYNC | PVMW_MIGRATION); + DEFINE_PAGE_VMA_WALK(pvmw, (struct page *)old, vma, addr, + PVMW_SYNC | PVMW_MIGRATION); struct page *new; pte_t pte; swp_entry_t entry; @@ -184,7 +185,7 @@ static bool remove_migration_pte(struct page *page, struct vm_area_struct *vma, if (PageKsm(page)) new = page; else - new = page - pvmw.page->index + + new = page - pvmw.pgoff + linear_page_index(vma, pvmw.address); #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c index f7b331081791..1187f9c1ec5b 100644 --- a/mm/page_vma_mapped.c +++ b/mm/page_vma_mapped.c @@ -53,18 +53,6 @@ static bool map_pte(struct page_vma_mapped_walk *pvmw) return true; } -static inline bool pfn_is_match(struct page *page, unsigned long pfn) -{ - unsigned long page_pfn = page_to_pfn(page); - - /* normal page and hugetlbfs page */ - if (!PageTransCompound(page) || PageHuge(page)) - return page_pfn == pfn; - - /* THP can be referenced by any subpage */ - return pfn >= page_pfn && pfn - page_pfn < thp_nr_pages(page); -} - /** * check_pte - check if @pvmw->page is mapped at the @pvmw->pte * @pvmw: page_vma_mapped_walk struct, includes a pair pte and page for checking @@ -116,7 +104,17 @@ static bool check_pte(struct page_vma_mapped_walk *pvmw) pfn = pte_pfn(*pvmw->pte); } - return pfn_is_match(pvmw->page, pfn); + return (pfn - pvmw->pfn) < pvmw->nr_pages; +} + +/* Returns true if the two ranges overlap. Careful to not overflow. */ +static bool check_pmd(unsigned long pfn, struct page_vma_mapped_walk *pvmw) +{ + if ((pfn + HPAGE_PMD_NR - 1) < pvmw->pfn) + return false; + if (pfn > pvmw->pfn + pvmw->nr_pages - 1) + return false; + return true; } static void step_forward(struct page_vma_mapped_walk *pvmw, unsigned long size) @@ -127,7 +125,7 @@ static void step_forward(struct page_vma_mapped_walk *pvmw, unsigned long size) } /** - * page_vma_mapped_walk - check if @pvmw->page is mapped in @pvmw->vma at + * page_vma_mapped_walk - check if @pvmw->pfn is mapped in @pvmw->vma at * @pvmw->address * @pvmw: pointer to struct page_vma_mapped_walk. page, vma, address and flags * must be set. pmd, pte and ptl must be NULL. @@ -152,8 +150,8 @@ static void step_forward(struct page_vma_mapped_walk *pvmw, unsigned long size) */ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw) { - struct mm_struct *mm = pvmw->vma->vm_mm; - struct page *page = pvmw->page; + struct vm_area_struct *vma = pvmw->vma; + struct mm_struct *mm = vma->vm_mm; unsigned long end; pgd_t *pgd; p4d_t *p4d; @@ -164,32 +162,26 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw) if (pvmw->pmd && !pvmw->pte) return not_found(pvmw); - if (unlikely(PageHuge(page))) { + if (unlikely(is_vm_hugetlb_page(vma))) { + unsigned long size = pvmw->nr_pages * PAGE_SIZE; /* The only possible mapping was handled on last iteration */ if (pvmw->pte) return not_found(pvmw); /* when pud is not present, pte will be NULL */ - pvmw->pte = huge_pte_offset(mm, pvmw->address, page_size(page)); + pvmw->pte = huge_pte_offset(mm, pvmw->address, size); if (!pvmw->pte) return false; - pvmw->ptl = huge_pte_lockptr(page_hstate(page), mm, pvmw->pte); + pvmw->ptl = huge_pte_lockptr(size_to_hstate(size), mm, + pvmw->pte); spin_lock(pvmw->ptl); if (!check_pte(pvmw)) return not_found(pvmw); return true; } - /* - * Seek to next pte only makes sense for THP. - * But more important than that optimization, is to filter out - * any PageKsm page: whose page->index misleads vma_address() - * and vma_address_end() to disaster. - */ - end = PageTransCompound(page) ? - vma_address_end(page, pvmw->vma) : - pvmw->address + PAGE_SIZE; + end = vma_address_end(pvmw); if (pvmw->pte) goto next_pte; restart: @@ -224,7 +216,7 @@ restart: if (likely(pmd_trans_huge(pmde))) { if (pvmw->flags & PVMW_MIGRATION) return not_found(pvmw); - if (pmd_page(pmde) != page) + if (!check_pmd(pmd_pfn(pmde), pvmw)) return not_found(pvmw); return true; } @@ -236,7 +228,7 @@ restart: return not_found(pvmw); entry = pmd_to_swp_entry(pmde); if (!is_migration_entry(entry) || - pfn_swap_entry_to_page(entry) != page) + !check_pmd(swp_offset(entry), pvmw)) return not_found(pvmw); return true; } @@ -250,7 +242,8 @@ restart: * cleared *pmd but not decremented compound_mapcount(). */ if ((pvmw->flags & PVMW_SYNC) && - PageTransCompound(page)) { + transparent_hugepage_active(vma) && + (pvmw->nr_pages >= HPAGE_PMD_NR)) { spinlock_t *ptl = pmd_lock(mm, pvmw->pmd); spin_unlock(ptl); @@ -307,7 +300,8 @@ next_pte: int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma) { struct page_vma_mapped_walk pvmw = { - .page = page, + .pfn = page_to_pfn(page), + .nr_pages = 1, .vma = vma, .flags = PVMW_SYNC, }; diff --git a/mm/rmap.c b/mm/rmap.c index a7f06b76b503..e27ba4172069 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -940,7 +940,7 @@ static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma, */ mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE, 0, vma, vma->vm_mm, address, - vma_address_end(page, vma)); + vma_address_end(&pvmw)); mmu_notifier_invalidate_range_start(&range); while (page_vma_mapped_walk(&pvmw)) { @@ -1437,8 +1437,7 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, * Note that the page can not be free in this function as call of * try_to_unmap() must hold a reference on the page. */ - range.end = PageKsm(page) ? - address + PAGE_SIZE : vma_address_end(page, vma); + range.end = vma_address_end(&pvmw); mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, address, range.end); if (PageHuge(page)) { @@ -1732,8 +1731,7 @@ static bool try_to_migrate_one(struct page *page, struct vm_area_struct *vma, * Note that the page can not be free in this function as call of * try_to_unmap() must hold a reference on the page. */ - range.end = PageKsm(page) ? - address + PAGE_SIZE : vma_address_end(page, vma); + range.end = vma_address_end(&pvmw); mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, address, range.end); if (PageHuge(page)) {