diff options
Diffstat (limited to 'mm/gup.c')
| -rw-r--r-- | mm/gup.c | 1609 |
1 files changed, 952 insertions, 657 deletions
@@ -5,6 +5,7 @@ #include <linux/spinlock.h> #include <linux/mm.h> +#include <linux/memfd.h> #include <linux/memremap.h> #include <linux/pagemap.h> #include <linux/rmap.h> @@ -17,6 +18,7 @@ #include <linux/hugetlb.h> #include <linux/migrate.h> #include <linux/mm_inline.h> +#include <linux/pagevec.h> #include <linux/sched/mm.h> #include <linux/shmem_fs.h> @@ -24,6 +26,7 @@ #include <asm/tlbflush.h> #include "internal.h" +#include "swap.h" struct follow_page_context { struct dev_pagemap *pgmap; @@ -50,7 +53,12 @@ static inline void sanity_check_pinned_pages(struct page **pages, */ for (; npages; npages--, pages++) { struct page *page = *pages; - struct folio *folio = page_folio(page); + struct folio *folio; + + if (!page) + continue; + + folio = page_folio(page); if (is_zero_page(page) || !folio_test_anon(folio)) @@ -76,7 +84,7 @@ retry: folio = page_folio(page); if (WARN_ON_ONCE(folio_ref_count(folio) < 0)) return NULL; - if (unlikely(!folio_ref_try_add_rcu(folio, refs))) + if (unlikely(!folio_ref_try_add(folio, refs))) return NULL; /* @@ -89,172 +97,82 @@ retry: * belongs to this folio. */ if (unlikely(page_folio(page) != folio)) { - if (!put_devmap_managed_page_refs(&folio->page, refs)) - folio_put_refs(folio, refs); + folio_put_refs(folio, refs); goto retry; } return folio; } -/** - * try_grab_folio() - Attempt to get or pin a folio. - * @page: pointer to page to be grabbed - * @refs: the value to (effectively) add to the folio's refcount - * @flags: gup flags: these are the FOLL_* flag values. - * - * "grab" names in this file mean, "look at flags to decide whether to use - * FOLL_PIN or FOLL_GET behavior, when incrementing the folio's refcount. - * - * Either FOLL_PIN or FOLL_GET (or neither) must be set, but not both at the - * same time. (That's true throughout the get_user_pages*() and - * pin_user_pages*() APIs.) Cases: - * - * FOLL_GET: folio's refcount will be incremented by @refs. - * - * FOLL_PIN on large folios: folio's refcount will be incremented by - * @refs, and its pincount will be incremented by @refs. - * - * FOLL_PIN on single-page folios: folio's refcount will be incremented by - * @refs * GUP_PIN_COUNTING_BIAS. - * - * Return: The folio containing @page (with refcount appropriately - * incremented) for success, or NULL upon failure. If neither FOLL_GET - * nor FOLL_PIN was set, that's considered failure, and furthermore, - * a likely bug in the caller, so a warning is also emitted. - */ -struct folio *try_grab_folio(struct page *page, int refs, unsigned int flags) -{ - struct folio *folio; - - if (WARN_ON_ONCE((flags & (FOLL_GET | FOLL_PIN)) == 0)) - return NULL; - - if (unlikely(!(flags & FOLL_PCI_P2PDMA) && is_pci_p2pdma_page(page))) - return NULL; - - if (flags & FOLL_GET) - return try_get_folio(page, refs); - - /* FOLL_PIN is set */ - - /* - * Don't take a pin on the zero page - it's not going anywhere - * and it is used in a *lot* of places. - */ - if (is_zero_page(page)) - return page_folio(page); - - folio = try_get_folio(page, refs); - if (!folio) - return NULL; - - /* - * Can't do FOLL_LONGTERM + FOLL_PIN gup fast path if not in a - * right zone, so fail and let the caller fall back to the slow - * path. - */ - if (unlikely((flags & FOLL_LONGTERM) && - !folio_is_longterm_pinnable(folio))) { - if (!put_devmap_managed_page_refs(&folio->page, refs)) - folio_put_refs(folio, refs); - return NULL; - } - - /* - * When pinning a large folio, use an exact count to track it. - * - * However, be sure to *also* increment the normal folio - * refcount field at least once, so that the folio really - * is pinned. That's why the refcount from the earlier - * try_get_folio() is left intact. - */ - if (folio_test_large(folio)) - atomic_add(refs, &folio->_pincount); - else - folio_ref_add(folio, - refs * (GUP_PIN_COUNTING_BIAS - 1)); - /* - * Adjust the pincount before re-checking the PTE for changes. - * This is essentially a smp_mb() and is paired with a memory - * barrier in folio_try_share_anon_rmap_*(). - */ - smp_mb__after_atomic(); - - node_stat_mod_folio(folio, NR_FOLL_PIN_ACQUIRED, refs); - - return folio; -} - static void gup_put_folio(struct folio *folio, int refs, unsigned int flags) { if (flags & FOLL_PIN) { if (is_zero_folio(folio)) return; node_stat_mod_folio(folio, NR_FOLL_PIN_RELEASED, refs); - if (folio_test_large(folio)) + if (folio_has_pincount(folio)) atomic_sub(refs, &folio->_pincount); else refs *= GUP_PIN_COUNTING_BIAS; } - if (!put_devmap_managed_page_refs(&folio->page, refs)) - folio_put_refs(folio, refs); + folio_put_refs(folio, refs); } /** - * try_grab_page() - elevate a page's refcount by a flag-dependent amount - * @page: pointer to page to be grabbed - * @flags: gup flags: these are the FOLL_* flag values. + * try_grab_folio() - add a folio's refcount by a flag-dependent amount + * @folio: pointer to folio to be grabbed + * @refs: the value to (effectively) add to the folio's refcount + * @flags: gup flags: these are the FOLL_* flag values * * This might not do anything at all, depending on the flags argument. * * "grab" names in this file mean, "look at flags to decide whether to use - * FOLL_PIN or FOLL_GET behavior, when incrementing the page's refcount. + * FOLL_PIN or FOLL_GET behavior, when incrementing the folio's refcount. * * Either FOLL_PIN or FOLL_GET (or neither) may be set, but not both at the same - * time. Cases: please see the try_grab_folio() documentation, with - * "refs=1". + * time. * * Return: 0 for success, or if no action was required (if neither FOLL_PIN * nor FOLL_GET was set, nothing is done). A negative error code for failure: * - * -ENOMEM FOLL_GET or FOLL_PIN was set, but the page could not + * -ENOMEM FOLL_GET or FOLL_PIN was set, but the folio could not * be grabbed. + * + * It is called when we have a stable reference for the folio, typically in + * GUP slow path. */ -int __must_check try_grab_page(struct page *page, unsigned int flags) +int __must_check try_grab_folio(struct folio *folio, int refs, + unsigned int flags) { - struct folio *folio = page_folio(page); - if (WARN_ON_ONCE(folio_ref_count(folio) <= 0)) return -ENOMEM; - if (unlikely(!(flags & FOLL_PCI_P2PDMA) && is_pci_p2pdma_page(page))) + if (unlikely(!(flags & FOLL_PCI_P2PDMA) && is_pci_p2pdma_page(&folio->page))) return -EREMOTEIO; if (flags & FOLL_GET) - folio_ref_inc(folio); + folio_ref_add(folio, refs); else if (flags & FOLL_PIN) { /* * Don't take a pin on the zero page - it's not going anywhere * and it is used in a *lot* of places. */ - if (is_zero_page(page)) + if (is_zero_folio(folio)) return 0; /* - * Similar to try_grab_folio(): be sure to *also* - * increment the normal page refcount field at least once, + * Increment the normal page refcount field at least once, * so that the page really is pinned. */ - if (folio_test_large(folio)) { - folio_ref_add(folio, 1); - atomic_add(1, &folio->_pincount); + if (folio_has_pincount(folio)) { + folio_ref_add(folio, refs); + atomic_add(refs, &folio->_pincount); } else { - folio_ref_add(folio, GUP_PIN_COUNTING_BIAS); + folio_ref_add(folio, refs * GUP_PIN_COUNTING_BIAS); } - node_stat_mod_folio(folio, NR_FOLL_PIN_ACQUIRED, 1); + node_stat_mod_folio(folio, NR_FOLL_PIN_ACQUIRED, refs); } return 0; @@ -277,6 +195,19 @@ void unpin_user_page(struct page *page) EXPORT_SYMBOL(unpin_user_page); /** + * unpin_folio() - release a dma-pinned folio + * @folio: pointer to folio to be released + * + * Folios that were pinned via memfd_pin_folios() or other similar routines + * must be released either using unpin_folio() or unpin_folios(). + */ +void unpin_folio(struct folio *folio) +{ + gup_put_folio(folio, 1, FOLL_PIN); +} +EXPORT_SYMBOL_GPL(unpin_folio); + +/** * folio_add_pin - Try to get an additional pin on a pinned folio * @folio: The folio to be pinned * @@ -293,7 +224,7 @@ void folio_add_pin(struct folio *folio) * page refcount field at least once, so that the page really is * pinned. */ - if (folio_test_large(folio)) { + if (folio_has_pincount(folio)) { WARN_ON_ONCE(atomic_read(&folio->_pincount) < 1); folio_ref_inc(folio); atomic_inc(&folio->_pincount); @@ -378,7 +309,7 @@ void unpin_user_pages_dirty_lock(struct page **pages, unsigned long npages, * 1) This code sees the page as already dirty, so it * skips the call to set_page_dirty(). That could happen * because clear_page_dirty_for_io() called - * page_mkclean(), followed by set_page_dirty(). + * folio_mkclean(), followed by set_page_dirty(). * However, now the page is going to get written back, * which meets the original intention of setting it * dirty, so all is well: clear_page_dirty_for_io() goes @@ -440,7 +371,7 @@ void unpin_user_page_range_dirty_lock(struct page *page, unsigned long npages, } EXPORT_SYMBOL(unpin_user_page_range_dirty_lock); -static void unpin_user_pages_lockless(struct page **pages, unsigned long npages) +static void gup_fast_unpin_user_pages(struct page **pages, unsigned long npages) { unsigned long i; struct folio *folio; @@ -482,12 +413,63 @@ void unpin_user_pages(struct page **pages, unsigned long npages) sanity_check_pinned_pages(pages, npages); for (i = 0; i < npages; i += nr) { + if (!pages[i]) { + nr = 1; + continue; + } folio = gup_folio_next(pages, npages, i, &nr); gup_put_folio(folio, nr, FOLL_PIN); } } EXPORT_SYMBOL(unpin_user_pages); +/** + * unpin_user_folio() - release pages of a folio + * @folio: pointer to folio to be released + * @npages: number of pages of same folio + * + * Release npages of the folio + */ +void unpin_user_folio(struct folio *folio, unsigned long npages) +{ + gup_put_folio(folio, npages, FOLL_PIN); +} +EXPORT_SYMBOL(unpin_user_folio); + +/** + * unpin_folios() - release an array of gup-pinned folios. + * @folios: array of folios to be marked dirty and released. + * @nfolios: number of folios in the @folios array. + * + * For each folio in the @folios array, release the folio using gup_put_folio. + * + * Please see the unpin_folio() documentation for details. + */ +void unpin_folios(struct folio **folios, unsigned long nfolios) +{ + unsigned long i = 0, j; + + /* + * If this WARN_ON() fires, then the system *might* be leaking folios + * (by leaving them pinned), but probably not. More likely, gup/pup + * returned a hard -ERRNO error to the caller, who erroneously passed + * it here. + */ + if (WARN_ON(IS_ERR_VALUE(nfolios))) + return; + + while (i < nfolios) { + for (j = i + 1; j < nfolios; j++) + if (folios[i] != folios[j]) + break; + + if (folios[i]) + gup_put_folio(folios[i], j - i, FOLL_PIN); + i = j; + } +} +EXPORT_SYMBOL_GPL(unpin_folios); + /* * Set the MMF_HAS_PINNED if not set yet; after set it'll be there for the mm's * lifecycle. Avoid setting the bit unless necessary, or it might cause write @@ -500,23 +482,319 @@ static inline void mm_set_has_pinned_flag(unsigned long *mm_flags) } #ifdef CONFIG_MMU + +#ifdef CONFIG_HAVE_GUP_FAST +static int record_subpages(struct page *page, unsigned long sz, + unsigned long addr, unsigned long end, + struct page **pages) +{ + struct page *start_page; + int nr; + + start_page = nth_page(page, (addr & (sz - 1)) >> PAGE_SHIFT); + for (nr = 0; addr != end; nr++, addr += PAGE_SIZE) + pages[nr] = nth_page(start_page, nr); + + return nr; +} + +/** + * try_grab_folio_fast() - Attempt to get or pin a folio in fast path. + * @page: pointer to page to be grabbed + * @refs: the value to (effectively) add to the folio's refcount + * @flags: gup flags: these are the FOLL_* flag values. + * + * "grab" names in this file mean, "look at flags to decide whether to use + * FOLL_PIN or FOLL_GET behavior, when incrementing the folio's refcount. + * + * Either FOLL_PIN or FOLL_GET (or neither) must be set, but not both at the + * same time. (That's true throughout the get_user_pages*() and + * pin_user_pages*() APIs.) Cases: + * + * FOLL_GET: folio's refcount will be incremented by @refs. + * + * FOLL_PIN on large folios: folio's refcount will be incremented by + * @refs, and its pincount will be incremented by @refs. + * + * FOLL_PIN on single-page folios: folio's refcount will be incremented by + * @refs * GUP_PIN_COUNTING_BIAS. + * + * Return: The folio containing @page (with refcount appropriately + * incremented) for success, or NULL upon failure. If neither FOLL_GET + * nor FOLL_PIN was set, that's considered failure, and furthermore, + * a likely bug in the caller, so a warning is also emitted. + * + * It uses add ref unless zero to elevate the folio refcount and must be called + * in fast path only. + */ +static struct folio *try_grab_folio_fast(struct page *page, int refs, + unsigned int flags) +{ + struct folio *folio; + + /* Raise warn if it is not called in fast GUP */ + VM_WARN_ON_ONCE(!irqs_disabled()); + + if (WARN_ON_ONCE((flags & (FOLL_GET | FOLL_PIN)) == 0)) + return NULL; + + if (unlikely(!(flags & FOLL_PCI_P2PDMA) && is_pci_p2pdma_page(page))) + return NULL; + + if (flags & FOLL_GET) + return try_get_folio(page, refs); + + /* FOLL_PIN is set */ + + /* + * Don't take a pin on the zero page - it's not going anywhere + * and it is used in a *lot* of places. + */ + if (is_zero_page(page)) + return page_folio(page); + + folio = try_get_folio(page, refs); + if (!folio) + return NULL; + + /* + * Can't do FOLL_LONGTERM + FOLL_PIN gup fast path if not in a + * right zone, so fail and let the caller fall back to the slow + * path. + */ + if (unlikely((flags & FOLL_LONGTERM) && + !folio_is_longterm_pinnable(folio))) { + folio_put_refs(folio, refs); + return NULL; + } + + /* + * When pinning a large folio, use an exact count to track it. + * + * However, be sure to *also* increment the normal folio + * refcount field at least once, so that the folio really + * is pinned. That's why the refcount from the earlier + * try_get_folio() is left intact. + */ + if (folio_has_pincount(folio)) + atomic_add(refs, &folio->_pincount); + else + folio_ref_add(folio, + refs * (GUP_PIN_COUNTING_BIAS - 1)); + /* + * Adjust the pincount before re-checking the PTE for changes. + * This is essentially a smp_mb() and is paired with a memory + * barrier in folio_try_share_anon_rmap_*(). + */ + smp_mb__after_atomic(); + + node_stat_mod_folio(folio, NR_FOLL_PIN_ACQUIRED, refs); + + return folio; +} +#endif /* CONFIG_HAVE_GUP_FAST */ + +/* Common code for can_follow_write_* */ +static inline bool can_follow_write_common(struct page *page, + struct vm_area_struct *vma, unsigned int flags) +{ + /* Maybe FOLL_FORCE is set to override it? */ + if (!(flags & FOLL_FORCE)) + return false; + + /* But FOLL_FORCE has no effect on shared mappings */ + if (vma->vm_flags & (VM_MAYSHARE | VM_SHARED)) + return false; + + /* ... or read-only private ones */ + if (!(vma->vm_flags & VM_MAYWRITE)) + return false; + + /* ... or already writable ones that just need to take a write fault */ + if (vma->vm_flags & VM_WRITE) + return false; + + /* + * See can_change_pte_writable(): we broke COW and could map the page + * writable if we have an exclusive anonymous page ... + */ + return page && PageAnon(page) && PageAnonExclusive(page); +} + static struct page *no_page_table(struct vm_area_struct *vma, - unsigned int flags) + unsigned int flags, unsigned long address) { + if (!(flags & FOLL_DUMP)) + return NULL; + /* - * When core dumping an enormous anonymous area that nobody - * has touched so far, we don't want to allocate unnecessary pages or + * When core dumping, we don't want to allocate unnecessary pages or * page tables. Return error instead of NULL to skip handle_mm_fault, * then get_dump_page() will return NULL to leave a hole in the dump. * But we can only make this optimization where a hole would surely * be zero-filled if handle_mm_fault() actually did handle it. */ - if ((flags & FOLL_DUMP) && - (vma_is_anonymous(vma) || !vma->vm_ops->fault)) + if (is_vm_hugetlb_page(vma)) { + struct hstate *h = hstate_vma(vma); + + if (!hugetlbfs_pagecache_present(h, vma, address)) + return ERR_PTR(-EFAULT); + } else if ((vma_is_anonymous(vma) || !vma->vm_ops->fault)) { + return ERR_PTR(-EFAULT); + } + + return NULL; +} + +#ifdef CONFIG_PGTABLE_HAS_HUGE_LEAVES +/* FOLL_FORCE can write to even unwritable PUDs in COW mappings. */ +static inline bool can_follow_write_pud(pud_t pud, struct page *page, + struct vm_area_struct *vma, + unsigned int flags) +{ + /* If the pud is writable, we can write to the page. */ + if (pud_write(pud)) + return true; + + return can_follow_write_common(page, vma, flags); +} + +static struct page *follow_huge_pud(struct vm_area_struct *vma, + unsigned long addr, pud_t *pudp, + int flags, struct follow_page_context *ctx) +{ + struct mm_struct *mm = vma->vm_mm; + struct page *page; + pud_t pud = *pudp; + unsigned long pfn = pud_pfn(pud); + int ret; + + assert_spin_locked(pud_lockptr(mm, pudp)); + + if (!pud_present(pud)) + return NULL; + + if ((flags & FOLL_WRITE) && + !can_follow_write_pud(pud, pfn_to_page(pfn), vma, flags)) + return NULL; + + pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT; + + if (IS_ENABLED(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) && + pud_devmap(pud)) { + /* + * device mapped pages can only be returned if the caller + * will manage the page reference count. + * + * At least one of FOLL_GET | FOLL_PIN must be set, so + * assert that here: + */ + if (!(flags & (FOLL_GET | FOLL_PIN))) + return ERR_PTR(-EEXIST); + + if (flags & FOLL_TOUCH) + touch_pud(vma, addr, pudp, flags & FOLL_WRITE); + + ctx->pgmap = get_dev_pagemap(pfn, ctx->pgmap); + if (!ctx->pgmap) + return ERR_PTR(-EFAULT); + } + + page = pfn_to_page(pfn); + + if (!pud_devmap(pud) && !pud_write(pud) && + gup_must_unshare(vma, flags, page)) + return ERR_PTR(-EMLINK); + + ret = try_grab_folio(page_folio(page), 1, flags); + if (ret) + page = ERR_PTR(ret); + else + ctx->page_mask = HPAGE_PUD_NR - 1; + + return page; +} + +/* FOLL_FORCE can write to even unwritable PMDs in COW mappings. */ +static inline bool can_follow_write_pmd(pmd_t pmd, struct page *page, + struct vm_area_struct *vma, + unsigned int flags) +{ + /* If the pmd is writable, we can write to the page. */ + if (pmd_write(pmd)) + return true; + + if (!can_follow_write_common(page, vma, flags)) + return false; + + /* ... and a write-fault isn't required for other reasons. */ + if (pmd_needs_soft_dirty_wp(vma, pmd)) + return false; + return !userfaultfd_huge_pmd_wp(vma, pmd); +} + +static struct page *follow_huge_pmd(struct vm_area_struct *vma, + unsigned long addr, pmd_t *pmd, + unsigned int flags, + struct follow_page_context *ctx) +{ + struct mm_struct *mm = vma->vm_mm; + pmd_t pmdval = *pmd; + struct page *page; + int ret; + + assert_spin_locked(pmd_lockptr(mm, pmd)); + + page = pmd_page(pmdval); + if ((flags & FOLL_WRITE) && + !can_follow_write_pmd(pmdval, page, vma, flags)) + return NULL; + + /* Avoid dumping huge zero page */ + if ((flags & FOLL_DUMP) && is_huge_zero_pmd(pmdval)) return ERR_PTR(-EFAULT); + + if (pmd_protnone(*pmd) && !gup_can_follow_protnone(vma, flags)) + return NULL; + + if (!pmd_write(pmdval) && gup_must_unshare(vma, flags, page)) + return ERR_PTR(-EMLINK); + + VM_BUG_ON_PAGE((flags & FOLL_PIN) && PageAnon(page) && + !PageAnonExclusive(page), page); + + ret = try_grab_folio(page_folio(page), 1, flags); + if (ret) + return ERR_PTR(ret); + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE + if (pmd_trans_huge(pmdval) && (flags & FOLL_TOUCH)) + touch_pmd(vma, addr, pmd, flags & FOLL_WRITE); +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ + + page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; + ctx->page_mask = HPAGE_PMD_NR - 1; + + return page; +} + +#else /* CONFIG_PGTABLE_HAS_HUGE_LEAVES */ +static struct page *follow_huge_pud(struct vm_area_struct *vma, + unsigned long addr, pud_t *pudp, + int flags, struct follow_page_context *ctx) +{ return NULL; } +static struct page *follow_huge_pmd(struct vm_area_struct *vma, + unsigned long addr, pmd_t *pmd, + unsigned int flags, + struct follow_page_context *ctx) +{ + return NULL; +} +#endif /* CONFIG_PGTABLE_HAS_HUGE_LEAVES */ + static int follow_pfn_pte(struct vm_area_struct *vma, unsigned long address, pte_t *pte, unsigned int flags) { @@ -547,31 +825,11 @@ static inline bool can_follow_write_pte(pte_t pte, struct page *page, if (pte_write(pte)) return true; - /* Maybe FOLL_FORCE is set to override it? */ - if (!(flags & FOLL_FORCE)) - return false; - - /* But FOLL_FORCE has no effect on shared mappings */ - if (vma->vm_flags & (VM_MAYSHARE | VM_SHARED)) - return false; - - /* ... or read-only private ones */ - if (!(vma->vm_flags & VM_MAYWRITE)) - return false; - - /* ... or already writable ones that just need to take a write fault */ - if (vma->vm_flags & VM_WRITE) - return false; - - /* - * See can_change_pte_writable(): we broke COW and could map the page - * writable if we have an exclusive anonymous page ... - */ - if (!page || !PageAnon(page) || !PageAnonExclusive(page)) + if (!can_follow_write_common(page, vma, flags)) return false; /* ... and a write-fault isn't required for other reasons. */ - if (vma_soft_dirty_enabled(vma) && !pte_soft_dirty(pte)) + if (pte_needs_soft_dirty_wp(vma, pte)) return false; return !userfaultfd_pte_wp(vma, pte); } @@ -581,19 +839,15 @@ static struct page *follow_page_pte(struct vm_area_struct *vma, struct dev_pagemap **pgmap) { struct mm_struct *mm = vma->vm_mm; + struct folio *folio; struct page *page; spinlock_t *ptl; pte_t *ptep, pte; int ret; - /* FOLL_GET and FOLL_PIN are mutually exclusive. */ - if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) == - (FOLL_PIN | FOLL_GET))) - return ERR_PTR(-EINVAL); - ptep = pte_offset_map_lock(mm, pmd, address, &ptl); if (!ptep) - return no_page_table(vma, flags); + return no_page_table(vma, flags, address); pte = ptep_get(ptep); if (!pte_present(pte)) goto no_page; @@ -638,6 +892,7 @@ static struct page *follow_page_pte(struct vm_area_struct *vma, goto out; } } + folio = page_folio(page); if (!pte_write(pte) && gup_must_unshare(vma, flags, page)) { page = ERR_PTR(-EMLINK); @@ -647,8 +902,8 @@ static struct page *follow_page_pte(struct vm_area_struct *vma, VM_BUG_ON_PAGE((flags & FOLL_PIN) && PageAnon(page) && !PageAnonExclusive(page), page); - /* try_grab_page() does nothing unless FOLL_GET or FOLL_PIN is set. */ - ret = try_grab_page(page, flags); + /* try_grab_folio() does nothing unless FOLL_GET or FOLL_PIN is set. */ + ret = try_grab_folio(folio, 1, flags); if (unlikely(ret)) { page = ERR_PTR(ret); goto out; @@ -660,7 +915,7 @@ static struct page *follow_page_pte(struct vm_area_struct *vma, * Documentation/core-api/pin_user_pages.rst for details. */ if (flags & FOLL_PIN) { - ret = arch_make_page_accessible(page); + ret = arch_make_folio_accessible(folio); if (ret) { unpin_user_page(page); page = ERR_PTR(ret); @@ -669,14 +924,14 @@ static struct page *follow_page_pte(struct vm_area_struct *vma, } if (flags & FOLL_TOUCH) { if ((flags & FOLL_WRITE) && - !pte_dirty(pte) && !PageDirty(page)) - set_page_dirty(page); + !pte_dirty(pte) && !folio_test_dirty(folio)) + folio_mark_dirty(folio); /* * pte_mkyoung() would be more correct here, but atomic care * is needed to avoid losing the dirty bit: it is easier to use - * mark_page_accessed(). + * folio_mark_accessed(). */ - mark_page_accessed(page); + folio_mark_accessed(folio); } out: pte_unmap_unlock(ptep, ptl); @@ -685,7 +940,7 @@ no_page: pte_unmap_unlock(ptep, ptl); if (!pte_none(pte)) return NULL; - return no_page_table(vma, flags); + return no_page_table(vma, flags, address); } static struct page *follow_pmd_mask(struct vm_area_struct *vma, @@ -701,42 +956,42 @@ static struct page *follow_pmd_mask(struct vm_area_struct *vma, pmd = pmd_offset(pudp, address); pmdval = pmdp_get_lockless(pmd); if (pmd_none(pmdval)) - return no_page_table(vma, flags); + return no_page_table(vma, flags, address); if (!pmd_present(pmdval)) - return no_page_table(vma, flags); + return no_page_table(vma, flags, address); if (pmd_devmap(pmdval)) { ptl = pmd_lock(mm, pmd); page = follow_devmap_pmd(vma, address, pmd, flags, &ctx->pgmap); spin_unlock(ptl); if (page) return page; - return no_page_table(vma, flags); + return no_page_table(vma, flags, address); } - if (likely(!pmd_trans_huge(pmdval))) + if (likely(!pmd_leaf(pmdval))) return follow_page_pte(vma, address, pmd, flags, &ctx->pgmap); if (pmd_protnone(pmdval) && !gup_can_follow_protnone(vma, flags)) - return no_page_table(vma, flags); + return no_page_table(vma, flags, address); ptl = pmd_lock(mm, pmd); - if (unlikely(!pmd_present(*pmd))) { + pmdval = *pmd; + if (unlikely(!pmd_present(pmdval))) { spin_unlock(ptl); - return no_page_table(vma, flags); + return no_page_table(vma, flags, address); } - if (unlikely(!pmd_trans_huge(*pmd))) { + if (unlikely(!pmd_leaf(pmdval))) { spin_unlock(ptl); return follow_page_pte(vma, address, pmd, flags, &ctx->pgmap); } - if (flags & FOLL_SPLIT_PMD) { + if (pmd_trans_huge(pmdval) && (flags & FOLL_SPLIT_PMD)) { spin_unlock(ptl); split_huge_pmd(vma, pmd, address); /* If pmd was left empty, stuff a page table in there quickly */ return pte_alloc(mm, pmd) ? ERR_PTR(-ENOMEM) : follow_page_pte(vma, address, pmd, flags, &ctx->pgmap); } - page = follow_trans_huge_pmd(vma, address, pmd, flags); + page = follow_huge_pmd(vma, address, pmd, flags, ctx); spin_unlock(ptl); - ctx->page_mask = HPAGE_PMD_NR - 1; return page; } @@ -745,26 +1000,27 @@ static struct page *follow_pud_mask(struct vm_area_struct *vma, unsigned int flags, struct follow_page_context *ctx) { - pud_t *pud; + pud_t *pudp, pud; spinlock_t *ptl; struct page *page; struct mm_struct *mm = vma->vm_mm; - pud = pud_offset(p4dp, address); - if (pud_none(*pud)) - return no_page_table(vma, flags); - if (pud_devmap(*pud)) { - ptl = pud_lock(mm, pud); - page = follow_devmap_pud(vma, address, pud, flags, &ctx->pgmap); + pudp = pud_offset(p4dp, address); + pud = READ_ONCE(*pudp); + if (!pud_present(pud)) + return no_page_table(vma, flags, address); + if (pud_leaf(pud)) { + ptl = pud_lock(mm, pudp); + page = follow_huge_pud(vma, address, pudp, flags, ctx); spin_unlock(ptl); if (page) return page; - return no_page_table(vma, flags); + return no_page_table(vma, flags, address); } - if (unlikely(pud_bad(*pud))) - return no_page_table(vma, flags); + if (unlikely(pud_bad(pud))) + return no_page_table(vma, flags, address); - return follow_pmd_mask(vma, address, pud, flags, ctx); + return follow_pmd_mask(vma, address, pudp, flags, ctx); } static struct page *follow_p4d_mask(struct vm_area_struct *vma, @@ -772,16 +1028,16 @@ static struct page *follow_p4d_mask(struct vm_area_struct *vma, unsigned int flags, struct follow_page_context *ctx) { - p4d_t *p4d; + p4d_t *p4dp, p4d; - p4d = p4d_offset(pgdp, address); - if (p4d_none(*p4d)) - return no_page_table(vma, flags); - BUILD_BUG_ON(p4d_huge(*p4d)); - if (unlikely(p4d_bad(*p4d))) - return no_page_table(vma, flags); + p4dp = p4d_offset(pgdp, address); + p4d = READ_ONCE(*p4dp); + BUILD_BUG_ON(p4d_leaf(p4d)); + + if (!p4d_present(p4d) || p4d_bad(p4d)) + return no_page_table(vma, flags, address); - return follow_pud_mask(vma, address, p4d, flags, ctx); + return follow_pud_mask(vma, address, p4dp, flags, ctx); } /** @@ -814,45 +1070,20 @@ static struct page *follow_page_mask(struct vm_area_struct *vma, { pgd_t *pgd; struct mm_struct *mm = vma->vm_mm; + struct page *page; - ctx->page_mask = 0; - - /* - * Call hugetlb_follow_page_mask for hugetlb vmas as it will use - * special hugetlb page table walking code. This eliminates the - * need to check for hugetlb entries in the general walking code. - */ - if (is_vm_hugetlb_page(vma)) - return hugetlb_follow_page_mask(vma, address, flags, - &ctx->page_mask); + vma_pgtable_walk_begin(vma); + ctx->page_mask = 0; pgd = pgd_offset(mm, address); if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) - return no_page_table(vma, flags); - - return follow_p4d_mask(vma, address, pgd, flags, ctx); -} - -struct page *follow_page(struct vm_area_struct *vma, unsigned long address, - unsigned int foll_flags) -{ - struct follow_page_context ctx = { NULL }; - struct page *page; - - if (vma_is_secretmem(vma)) - return NULL; + page = no_page_table(vma, flags, address); + else + page = follow_p4d_mask(vma, address, pgd, flags, ctx); - if (WARN_ON_ONCE(foll_flags & FOLL_PIN)) - return NULL; + vma_pgtable_walk_end(vma); - /* - * We never set FOLL_HONOR_NUMA_FAULT because callers don't expect - * to fail on PROT_NONE-mapped pages. - */ - page = follow_page_mask(vma, address, foll_flags, &ctx); - if (ctx.pgmap) - put_dev_pagemap(ctx.pgmap); return page; } @@ -871,10 +1102,7 @@ static int get_gate_page(struct mm_struct *mm, unsigned long address, /* user gate pages are read-only */ if (gup_flags & FOLL_WRITE) return -EFAULT; - if (address > TASK_SIZE) - pgd = pgd_offset_k(address); - else - pgd = pgd_offset_gate(mm, address); + pgd = pgd_offset(mm, address); if (pgd_none(*pgd)) return -EFAULT; p4d = p4d_offset(pgd, address); @@ -901,7 +1129,7 @@ static int get_gate_page(struct mm_struct *mm, unsigned long address, goto unmap; *page = pte_page(entry); } - ret = try_grab_page(*page, gup_flags); + ret = try_grab_folio(page_folio(*page), 1, gup_flags); if (unlikely(ret)) goto unmap; out: @@ -917,19 +1145,19 @@ unmap: * to 0 and -EBUSY returned. */ static int faultin_page(struct vm_area_struct *vma, - unsigned long address, unsigned int *flags, bool unshare, + unsigned long address, unsigned int flags, bool unshare, int *locked) { unsigned int fault_flags = 0; vm_fault_t ret; - if (*flags & FOLL_NOFAULT) + if (flags & FOLL_NOFAULT) return -EFAULT; - if (*flags & FOLL_WRITE) + if (flags & FOLL_WRITE) fault_flags |= FAULT_FLAG_WRITE; - if (*flags & FOLL_REMOTE) + if (flags & FOLL_REMOTE) fault_flags |= FAULT_FLAG_REMOTE; - if (*flags & FOLL_UNLOCKABLE) { + if (flags & FOLL_UNLOCKABLE) { fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; /* * FAULT_FLAG_INTERRUPTIBLE is opt-in. GUP callers must set @@ -937,12 +1165,12 @@ static int faultin_page(struct vm_area_struct *vma, * That's because some callers may not be prepared to * handle early exits caused by non-fatal signals. */ - if (*flags & FOLL_INTERRUPTIBLE) + if (flags & FOLL_INTERRUPTIBLE) fault_flags |= FAULT_FLAG_INTERRUPTIBLE; } - if (*flags & FOLL_NOWAIT) + if (flags & FOLL_NOWAIT) fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT; - if (*flags & FOLL_TRIED) { + if (flags & FOLL_TRIED) { /* * Note: FAULT_FLAG_ALLOW_RETRY and FAULT_FLAG_TRIED * can co-exist @@ -976,7 +1204,7 @@ static int faultin_page(struct vm_area_struct *vma, } if (ret & VM_FAULT_ERROR) { - int err = vm_fault_to_errno(ret, *flags); + int err = vm_fault_to_errno(ret, flags); if (err) return err; @@ -1045,6 +1273,9 @@ static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags) if ((gup_flags & FOLL_LONGTERM) && vma_is_fsdax(vma)) return -EOPNOTSUPP; + if ((gup_flags & FOLL_SPLIT_PMD) && is_vm_hugetlb_page(vma)) + return -EOPNOTSUPP; + if (vma_is_secretmem(vma)) return -EFAULT; @@ -1056,9 +1287,6 @@ static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags) if (!(vm_flags & VM_WRITE) || (vm_flags & VM_SHADOW_STACK)) { if (!(gup_flags & FOLL_FORCE)) return -EFAULT; - /* hugetlb does not support FOLL_FORCE|FOLL_WRITE. */ - if (is_vm_hugetlb_page(vma)) - return -EFAULT; /* * We used to let the write,force case do COW in a * VM_MAYWRITE VM_SHARED !VM_WRITE vma, so ptrace could @@ -1197,15 +1425,34 @@ static long __get_user_pages(struct mm_struct *mm, start = untagged_addr_remote(mm, start); - VM_BUG_ON(!!pages != !!(gup_flags & (FOLL_GET | FOLL_PIN))); + VM_WARN_ON_ONCE(!!pages != !!(gup_flags & (FOLL_GET | FOLL_PIN))); + + /* FOLL_GET and FOLL_PIN are mutually exclusive. */ + VM_WARN_ON_ONCE((gup_flags & (FOLL_PIN | FOLL_GET)) == + (FOLL_PIN | FOLL_GET)); do { struct page *page; - unsigned int foll_flags = gup_flags; unsigned int page_increm; /* first iteration or cross vma bound */ if (!vma || start >= vma->vm_end) { + /* + * MADV_POPULATE_(READ|WRITE) wants to handle VMA + * lookups+error reporting differently. + */ + if (gup_flags & FOLL_MADV_POPULATE) { + vma = vma_lookup(mm, start); + if (!vma) { + ret = -ENOMEM; + goto out; + } + if (check_vma_flags(vma, gup_flags)) { + ret = -EINVAL; + goto out; + } + goto retry; + } vma = gup_vma_lookup(mm, start); if (!vma && in_gate_area(mm, start)) { ret = get_gate_page(mm, start & PAGE_MASK, @@ -1236,9 +1483,9 @@ retry: } cond_resched(); - page = follow_page_mask(vma, start, foll_flags, &ctx); + page = follow_page_mask(vma, start, gup_flags, &ctx); if (!page || PTR_ERR(page) == -EMLINK) { - ret = faultin_page(vma, start, &foll_flags, + ret = faultin_page(vma, start, gup_flags, PTR_ERR(page) == -EMLINK, locked); switch (ret) { case 0: @@ -1288,21 +1535,19 @@ next_page: * pages. */ if (page_increm > 1) { - struct folio *folio; + struct folio *folio = page_folio(page); /* * Since we already hold refcount on the * large folio, this should never fail. */ - folio = try_grab_folio(page, page_increm - 1, - foll_flags); - if (WARN_ON_ONCE(!folio)) { + if (try_grab_folio(folio, page_increm - 1, + gup_flags)) { /* * Release the 1st page ref if the * folio is problematic, fail hard. */ - gup_put_folio(page_folio(page), 1, - foll_flags); + gup_put_folio(folio, 1, gup_flags); ret = -EFAULT; goto out; } @@ -1685,35 +1930,35 @@ long populate_vma_page_range(struct vm_area_struct *vma, } /* - * faultin_vma_page_range() - populate (prefault) page tables inside the - * given VMA range readable/writable + * faultin_page_range() - populate (prefault) page tables inside the + * given range readable/writable * * This takes care of mlocking the pages, too, if VM_LOCKED is set. * - * @vma: target vma + * @mm: the mm to populate page tables in * @start: start address * @end: end address * @write: whether to prefault readable or writable * @locked: whether the mmap_lock is still held * - * Returns either number of processed pages in the vma, or a negative error - * code on error (see __get_user_pages()). + * Returns either number of processed pages in the MM, or a negative error + * code on error (see __get_user_pages()). Note that this function reports + * errors related to VMAs, such as incompatible mappings, as expected by + * MADV_POPULATE_(READ|WRITE). * - * vma->vm_mm->mmap_lock must be held. The range must be page-aligned and - * covered by the VMA. If it's released, *@locked will be set to 0. + * The range must be page-aligned. + * + * mm->mmap_lock must be held. If it's released, *@locked will be set to 0. */ -long faultin_vma_page_range(struct vm_area_struct *vma, unsigned long start, - unsigned long end, bool write, int *locked) +long faultin_page_range(struct mm_struct *mm, unsigned long start, + unsigned long end, bool write, int *locked) { - struct mm_struct *mm = vma->vm_mm; unsigned long nr_pages = (end - start) / PAGE_SIZE; int gup_flags; long ret; VM_BUG_ON(!PAGE_ALIGNED(start)); VM_BUG_ON(!PAGE_ALIGNED(end)); - VM_BUG_ON_VMA(start < vma->vm_start, vma); - VM_BUG_ON_VMA(end > vma->vm_end, vma); mmap_assert_locked(mm); /* @@ -1725,19 +1970,13 @@ long faultin_vma_page_range(struct vm_area_struct *vma, unsigned long start, * a poisoned page. * !FOLL_FORCE: Require proper access permissions. */ - gup_flags = FOLL_TOUCH | FOLL_HWPOISON | FOLL_UNLOCKABLE; + gup_flags = FOLL_TOUCH | FOLL_HWPOISON | FOLL_UNLOCKABLE | + FOLL_MADV_POPULATE; if (write) gup_flags |= FOLL_WRITE; - /* - * We want to report -EINVAL instead of -EFAULT for any permission - * problems or incompatible mappings. - */ - if (check_vma_flags(vma, gup_flags)) - return -EINVAL; - - ret = __get_user_pages(mm, start, nr_pages, gup_flags, - NULL, locked); + ret = __get_user_pages_locked(mm, start, nr_pages, NULL, locked, + gup_flags); lru_add_drain(); return ret; } @@ -1872,28 +2111,22 @@ static long __get_user_pages_locked(struct mm_struct *mm, unsigned long start, */ size_t fault_in_writeable(char __user *uaddr, size_t size) { - char __user *start = uaddr, *end; + const unsigned long start = (unsigned long)uaddr; + const unsigned long end = start + size; + unsigned long cur; if (unlikely(size == 0)) return 0; if (!user_write_access_begin(uaddr, size)) return size; - if (!PAGE_ALIGNED(uaddr)) { - unsafe_put_user(0, uaddr, out); - uaddr = (char __user *)PAGE_ALIGN((unsigned long)uaddr); - } - end = (char __user *)PAGE_ALIGN((unsigned long)start + size); - if (unlikely(end < start)) - end = NULL; - while (uaddr != end) { - unsafe_put_user(0, uaddr, out); - uaddr += PAGE_SIZE; - } + /* Stop once we overflow to 0. */ + for (cur = start; cur && cur < end; cur = PAGE_ALIGN_DOWN(cur + PAGE_SIZE)) + unsafe_put_user(0, (char __user *)cur, out); out: user_write_access_end(); - if (size > uaddr - start) - return size - (uaddr - start); + if (size > cur - start) + return size - (cur - start); return 0; } EXPORT_SYMBOL(fault_in_writeable); @@ -1947,26 +2180,24 @@ EXPORT_SYMBOL(fault_in_subpage_writeable); */ size_t fault_in_safe_writeable(const char __user *uaddr, size_t size) { - unsigned long start = (unsigned long)uaddr, end; + const unsigned long start = (unsigned long)uaddr; + const unsigned long end = start + size; + unsigned long cur; struct mm_struct *mm = current->mm; bool unlocked = false; if (unlikely(size == 0)) return 0; - end = PAGE_ALIGN(start + size); - if (end < start) - end = 0; mmap_read_lock(mm); - do { - if (fixup_user_fault(mm, start, FAULT_FLAG_WRITE, &unlocked)) + /* Stop once we overflow to 0. */ + for (cur = start; cur && cur < end; cur = PAGE_ALIGN_DOWN(cur + PAGE_SIZE)) + if (fixup_user_fault(mm, cur, FAULT_FLAG_WRITE, &unlocked)) break; - start = (start + PAGE_SIZE) & PAGE_MASK; - } while (start != end); mmap_read_unlock(mm); - if (size > (unsigned long)uaddr - start) - return size - ((unsigned long)uaddr - start); + if (size > cur - start) + return size - (cur - start); return 0; } EXPORT_SYMBOL(fault_in_safe_writeable); @@ -1981,30 +2212,24 @@ EXPORT_SYMBOL(fault_in_safe_writeable); */ size_t fault_in_readable(const char __user *uaddr, size_t size) { - const char __user *start = uaddr, *end; + const unsigned long start = (unsigned long)uaddr; + const unsigned long end = start + size; + unsigned long cur; volatile char c; if (unlikely(size == 0)) return 0; if (!user_read_access_begin(uaddr, size)) return size; - if (!PAGE_ALIGNED(uaddr)) { - unsafe_get_user(c, uaddr, out); - uaddr = (const char __user *)PAGE_ALIGN((unsigned long)uaddr); - } - end = (const char __user *)PAGE_ALIGN((unsigned long)start + size); - if (unlikely(end < start)) - end = NULL; - while (uaddr != end) { - unsafe_get_user(c, uaddr, out); - uaddr += PAGE_SIZE; - } + /* Stop once we overflow to 0. */ + for (cur = start; cur && cur < end; cur = PAGE_ALIGN_DOWN(cur + PAGE_SIZE)) + unsafe_get_user(c, (const char __user *)cur, out); out: user_read_access_end(); (void)c; - if (size > uaddr - start) - return size - (uaddr - start); + if (size > cur - start) + return size - (cur - start); return 0; } EXPORT_SYMBOL(fault_in_readable); @@ -2012,6 +2237,7 @@ EXPORT_SYMBOL(fault_in_readable); /** * get_dump_page() - pin user page in memory while writing it to core dump * @addr: user address + * @locked: a pointer to an int denoting whether the mmap sem is held * * Returns struct page pointer of user page pinned for dump, * to be freed afterwards by put_page(). @@ -2024,33 +2250,69 @@ EXPORT_SYMBOL(fault_in_readable); * Called without mmap_lock (takes and releases the mmap_lock by itself). */ #ifdef CONFIG_ELF_CORE -struct page *get_dump_page(unsigned long addr) +struct page *get_dump_page(unsigned long addr, int *locked) { struct page *page; - int locked = 0; int ret; - ret = __get_user_pages_locked(current->mm, addr, 1, &page, &locked, + ret = __get_user_pages_locked(current->mm, addr, 1, &page, locked, FOLL_FORCE | FOLL_DUMP | FOLL_GET); return (ret == 1) ? page : NULL; } #endif /* CONFIG_ELF_CORE */ #ifdef CONFIG_MIGRATION + /* - * Returns the number of collected pages. Return value is always >= 0. + * An array of either pages or folios ("pofs"). Although it may seem tempting to + * avoid this complication, by simply interpreting a list of folios as a list of + * pages, that approach won't work in the longer term, because eventually the + * layouts of struct page and struct folio will become completely different. + * Furthermore, this pof approach avoids excessive page_folio() calls. */ -static unsigned long collect_longterm_unpinnable_pages( - struct list_head *movable_page_list, - unsigned long nr_pages, - struct page **pages) +struct pages_or_folios { + union { + struct page **pages; + struct folio **folios; + void **entries; + }; + bool has_folios; + long nr_entries; +}; + +static struct folio *pofs_get_folio(struct pages_or_folios *pofs, long i) +{ + if (pofs->has_folios) + return pofs->folios[i]; + return page_folio(pofs->pages[i]); +} + +static void pofs_clear_entry(struct pages_or_folios *pofs, long i) +{ + pofs->entries[i] = NULL; +} + +static void pofs_unpin(struct pages_or_folios *pofs) +{ + if (pofs->has_folios) + unpin_folios(pofs->folios, pofs->nr_entries); + else + unpin_user_pages(pofs->pages, pofs->nr_entries); +} + +/* + * Returns the number of collected folios. Return value is always >= 0. + */ +static unsigned long collect_longterm_unpinnable_folios( + struct list_head *movable_folio_list, + struct pages_or_folios *pofs) { unsigned long i, collected = 0; struct folio *prev_folio = NULL; bool drain_allow = true; - for (i = 0; i < nr_pages; i++) { - struct folio *folio = page_folio(pages[i]); + for (i = 0; i < pofs->nr_entries; i++) { + struct folio *folio = pofs_get_folio(pofs, i); if (folio == prev_folio) continue; @@ -2065,7 +2327,7 @@ static unsigned long collect_longterm_unpinnable_pages( continue; if (folio_test_hugetlb(folio)) { - isolate_hugetlb(folio, movable_page_list); + folio_isolate_hugetlb(folio, movable_folio_list); continue; } @@ -2077,7 +2339,7 @@ static unsigned long collect_longterm_unpinnable_pages( if (!folio_isolate_lru(folio)) continue; - list_add_tail(&folio->lru, movable_page_list); + list_add_tail(&folio->lru, movable_folio_list); node_stat_mod_folio(folio, NR_ISOLATED_ANON + folio_is_file_lru(folio), folio_nr_pages(folio)); @@ -2087,31 +2349,31 @@ static unsigned long collect_longterm_unpinnable_pages( } /* - * Unpins all pages and migrates device coherent pages and movable_page_list. - * Returns -EAGAIN if all pages were successfully migrated or -errno for failure - * (or partial success). + * Unpins all folios and migrates device coherent folios and movable_folio_list. + * Returns -EAGAIN if all folios were successfully migrated or -errno for + * failure (or partial success). */ -static int migrate_longterm_unpinnable_pages( - struct list_head *movable_page_list, - unsigned long nr_pages, - struct page **pages) +static int +migrate_longterm_unpinnable_folios(struct list_head *movable_folio_list, + struct pages_or_folios *pofs) { int ret; unsigned long i; - for (i = 0; i < nr_pages; i++) { - struct folio *folio = page_folio(pages[i]); + for (i = 0; i < pofs->nr_entries; i++) { + struct folio *folio = pofs_get_folio(pofs, i); if (folio_is_device_coherent(folio)) { /* - * Migration will fail if the page is pinned, so convert - * the pin on the source page to a normal reference. + * Migration will fail if the folio is pinned, so + * convert the pin on the source folio to a normal + * reference. */ - pages[i] = NULL; + pofs_clear_entry(pofs, i); folio_get(folio); gup_put_folio(folio, 1, FOLL_PIN); - if (migrate_device_coherent_page(&folio->page)) { + if (migrate_device_coherent_folio(folio)) { ret = -EBUSY; goto err; } @@ -2120,23 +2382,24 @@ static int migrate_longterm_unpinnable_pages( } /* - * We can't migrate pages with unexpected references, so drop + * We can't migrate folios with unexpected references, so drop * the reference obtained by __get_user_pages_locked(). - * Migrating pages have been added to movable_page_list after + * Migrating folios have been added to movable_folio_list after * calling folio_isolate_lru() which takes a reference so the - * page won't be freed if it's migrating. + * folio won't be freed if it's migrating. */ - unpin_user_page(pages[i]); - pages[i] = NULL; + unpin_folio(folio); + pofs_clear_entry(pofs, i); } - if (!list_empty(movable_page_list)) { + if (!list_empty(movable_folio_list)) { struct migration_target_control mtc = { .nid = NUMA_NO_NODE, .gfp_mask = GFP_USER | __GFP_NOWARN, + .reason = MR_LONGTERM_PIN, }; - if (migrate_pages(movable_page_list, alloc_migration_target, + if (migrate_pages(movable_folio_list, alloc_migration_target, NULL, (unsigned long)&mtc, MIGRATE_SYNC, MR_LONGTERM_PIN, NULL)) { ret = -ENOMEM; @@ -2144,48 +2407,78 @@ static int migrate_longterm_unpinnable_pages( } } - putback_movable_pages(movable_page_list); + putback_movable_pages(movable_folio_list); return -EAGAIN; err: - for (i = 0; i < nr_pages; i++) - if (pages[i]) - unpin_user_page(pages[i]); - putback_movable_pages(movable_page_list); + pofs_unpin(pofs); + putback_movable_pages(movable_folio_list); return ret; } +static long +check_and_migrate_movable_pages_or_folios(struct pages_or_folios *pofs) +{ + LIST_HEAD(movable_folio_list); + unsigned long collected; + + collected = collect_longterm_unpinnable_folios(&movable_folio_list, + pofs); + if (!collected) + return 0; + + return migrate_longterm_unpinnable_folios(&movable_folio_list, pofs); +} + /* - * Check whether all pages are *allowed* to be pinned. Rather confusingly, all - * pages in the range are required to be pinned via FOLL_PIN, before calling - * this routine. + * Check whether all folios are *allowed* to be pinned indefinitely (long term). + * Rather confusingly, all folios in the range are required to be pinned via + * FOLL_PIN, before calling this routine. + * + * Return values: * - * If any pages in the range are not allowed to be pinned, then this routine - * will migrate those pages away, unpin all the pages in the range and return - * -EAGAIN. The caller should re-pin the entire range with FOLL_PIN and then - * call this routine again. + * 0: if everything is OK and all folios in the range are allowed to be pinned, + * then this routine leaves all folios pinned and returns zero for success. * - * If an error other than -EAGAIN occurs, this indicates a migration failure. - * The caller should give up, and propagate the error back up the call stack. + * -EAGAIN: if any folios in the range are not allowed to be pinned, then this + * routine will migrate those folios away, unpin all the folios in the range. If + * migration of the entire set of folios succeeds, then -EAGAIN is returned. The + * caller should re-pin the entire range with FOLL_PIN and then call this + * routine again. * - * If everything is OK and all pages in the range are allowed to be pinned, then - * this routine leaves all pages pinned and returns zero for success. + * -ENOMEM, or any other -errno: if an error *other* than -EAGAIN occurs, this + * indicates a migration failure. The caller should give up, and propagate the + * error back up the call stack. The caller does not need to unpin any folios in + * that case, because this routine will do the unpinning. + */ +static long check_and_migrate_movable_folios(unsigned long nr_folios, + struct folio **folios) +{ + struct pages_or_folios pofs = { + .folios = folios, + .has_folios = true, + .nr_entries = nr_folios, + }; + + return check_and_migrate_movable_pages_or_folios(&pofs); +} + +/* + * Return values and behavior are the same as those for + * check_and_migrate_movable_folios(). */ static long check_and_migrate_movable_pages(unsigned long nr_pages, struct page **pages) { - unsigned long collected; - LIST_HEAD(movable_page_list); + struct pages_or_folios pofs = { + .pages = pages, + .has_folios = false, + .nr_entries = nr_pages, + }; - collected = collect_longterm_unpinnable_pages(&movable_page_list, - nr_pages, pages); - if (!collected) - return 0; - - return migrate_longterm_unpinnable_pages(&movable_page_list, nr_pages, - pages); + return check_and_migrate_movable_pages_or_folios(&pofs); } #else static long check_and_migrate_movable_pages(unsigned long nr_pages, @@ -2193,6 +2486,12 @@ static long check_and_migrate_movable_pages(unsigned long nr_pages, { return 0; } + +static long check_and_migrate_movable_folios(unsigned long nr_folios, + struct folio **folios) +{ + return 0; +} #endif /* CONFIG_MIGRATION */ /* @@ -2243,7 +2542,7 @@ static bool is_valid_gup_args(struct page **pages, int *locked, * These flags not allowed to be specified externally to the gup * interfaces: * - FOLL_TOUCH/FOLL_PIN/FOLL_TRIED/FOLL_FAST_ONLY are internal only - * - FOLL_REMOTE is internal only and used on follow_page() + * - FOLL_REMOTE is internal only, set in (get|pin)_user_pages_remote() * - FOLL_UNLOCKABLE is internal only and used if locked is !NULL */ if (WARN_ON_ONCE(gup_flags & INTERNAL_GUP_FLAGS)) @@ -2421,7 +2720,7 @@ long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages, EXPORT_SYMBOL(get_user_pages_unlocked); /* - * Fast GUP + * GUP-fast * * get_user_pages_fast attempts to pin user pages by walking the page * tables directly and avoids taking locks. Thus the walker needs to be @@ -2435,7 +2734,7 @@ EXPORT_SYMBOL(get_user_pages_unlocked); * * Another way to achieve this is to batch up page table containing pages * belonging to more than one mm_user, then rcu_sched a callback to free those - * pages. Disabling interrupts will allow the fast_gup walker to both block + * pages. Disabling interrupts will allow the gup_fast() walker to both block * the rcu_sched callback, and an IPI that we broadcast for splitting THPs * (which is a relatively rare event). The code below adopts this strategy. * @@ -2447,21 +2746,22 @@ EXPORT_SYMBOL(get_user_pages_unlocked); * * *) ptes can be read atomically by the architecture. * - * *) access_ok is sufficient to validate userspace address ranges. + * *) valid user addesses are below TASK_MAX_SIZE * * The last two assumptions can be relaxed by the addition of helper functions. * * This code is based heavily on the PowerPC implementation by Nick Piggin. */ -#ifdef CONFIG_HAVE_FAST_GUP - +#ifdef CONFIG_HAVE_GUP_FAST /* - * Used in the GUP-fast path to determine whether a pin is permitted for a - * specific folio. + * Used in the GUP-fast path to determine whether GUP is permitted to work on + * a specific folio. * * This call assumes the caller has pinned the folio, that the lowest page table * level still points to this folio, and that interrupts have been disabled. * + * GUP-fast must reject all secretmem folios. + * * Writing to pinned file-backed dirty tracked folios is inherently problematic * (see comment describing the writable_file_mapping_allowed() function). We * therefore try to avoid the most egregious case of a long-term mapping doing @@ -2471,25 +2771,34 @@ EXPORT_SYMBOL(get_user_pages_unlocked); * in the fast path, so instead we whitelist known good cases and if in doubt, * fall back to the slow path. */ -static bool folio_fast_pin_allowed(struct folio *folio, unsigned int flags) +static bool gup_fast_folio_allowed(struct folio *folio, unsigned int flags) { + bool reject_file_backed = false; struct address_space *mapping; + bool check_secretmem = false; unsigned long mapping_flags; /* * If we aren't pinning then no problematic write can occur. A long term * pin is the most egregious case so this is the one we disallow. */ - if ((flags & (FOLL_PIN | FOLL_LONGTERM | FOLL_WRITE)) != + if ((flags & (FOLL_PIN | FOLL_LONGTERM | FOLL_WRITE)) == (FOLL_PIN | FOLL_LONGTERM | FOLL_WRITE)) - return true; + reject_file_backed = true; - /* The folio is pinned, so we can safely access folio fields. */ + /* We hold a folio reference, so we can safely access folio fields. */ + + /* secretmem folios are always order-0 folios. */ + if (IS_ENABLED(CONFIG_SECRETMEM) && !folio_test_large(folio)) + check_secretmem = true; + + if (!reject_file_backed && !check_secretmem) + return true; if (WARN_ON_ONCE(folio_test_slab(folio))) return false; - /* hugetlb mappings do not require dirty-tracking. */ + /* hugetlb neither requires dirty-tracking nor can be secretmem. */ if (folio_test_hugetlb(folio)) return true; @@ -2525,50 +2834,48 @@ static bool folio_fast_pin_allowed(struct folio *folio, unsigned int flags) /* * At this point, we know the mapping is non-null and points to an - * address_space object. The only remaining whitelisted file system is - * shmem. + * address_space object. */ - return shmem_mapping(mapping); + if (check_secretmem && secretmem_mapping(mapping)) + return false; + /* The only remaining allowed file system is shmem. */ + return !reject_file_backed || shmem_mapping(mapping); } -static void __maybe_unused undo_dev_pagemap(int *nr, int nr_start, - unsigned int flags, - struct page **pages) +static void __maybe_unused gup_fast_undo_dev_pagemap(int *nr, int nr_start, + unsigned int flags, struct page **pages) { while ((*nr) - nr_start) { - struct page *page = pages[--(*nr)]; + struct folio *folio = page_folio(pages[--(*nr)]); - ClearPageReferenced(page); - if (flags & FOLL_PIN) - unpin_user_page(page); - else - put_page(page); + folio_clear_referenced(folio); + gup_put_folio(folio, 1, flags); } } #ifdef CONFIG_ARCH_HAS_PTE_SPECIAL /* - * Fast-gup relies on pte change detection to avoid concurrent pgtable + * GUP-fast relies on pte change detection to avoid concurrent pgtable * operations. * - * To pin the page, fast-gup needs to do below in order: + * To pin the page, GUP-fast needs to do below in order: * (1) pin the page (by prefetching pte), then (2) check pte not changed. * * For the rest of pgtable operations where pgtable updates can be racy - * with fast-gup, we need to do (1) clear pte, then (2) check whether page + * with GUP-fast, we need to do (1) clear pte, then (2) check whether page * is pinned. * * Above will work for all pte-level operations, including THP split. * - * For THP collapse, it's a bit more complicated because fast-gup may be + * For THP collapse, it's a bit more complicated because GUP-fast may be * walking a pgtable page that is being freed (pte is still valid but pmd * can be cleared already). To avoid race in such condition, we need to * also check pmd here to make sure pmd doesn't change (corresponds to * pmdp_collapse_flush() in the THP collapse code path). */ -static int gup_pte_range(pmd_t pmd, pmd_t *pmdp, unsigned long addr, - unsigned long end, unsigned int flags, - struct page **pages, int *nr) +static int gup_fast_pte_range(pmd_t pmd, pmd_t *pmdp, unsigned long addr, + unsigned long end, unsigned int flags, struct page **pages, + int *nr) { struct dev_pagemap *pgmap = NULL; int nr_start = *nr, ret = 0; @@ -2601,7 +2908,7 @@ static int gup_pte_range(pmd_t pmd, pmd_t *pmdp, unsigned long addr, pgmap = get_dev_pagemap(pte_pfn(pte), pgmap); if (unlikely(!pgmap)) { - undo_dev_pagemap(nr, nr_start, flags, pages); + gup_fast_undo_dev_pagemap(nr, nr_start, flags, pages); goto pte_unmap; } } else if (pte_special(pte)) @@ -2610,22 +2917,17 @@ static int gup_pte_range(pmd_t pmd, pmd_t *pmdp, unsigned long addr, VM_BUG_ON(!pfn_valid(pte_pfn(pte))); page = pte_page(pte); - folio = try_grab_folio(page, 1, flags); + folio = try_grab_folio_fast(page, 1, flags); if (!folio) goto pte_unmap; - if (unlikely(folio_is_secretmem(folio))) { - gup_put_folio(folio, 1, flags); - goto pte_unmap; - } - if (unlikely(pmd_val(pmd) != pmd_val(*pmdp)) || unlikely(pte_val(pte) != pte_val(ptep_get(ptep)))) { gup_put_folio(folio, 1, flags); goto pte_unmap; } - if (!folio_fast_pin_allowed(folio, flags)) { + if (!gup_fast_folio_allowed(folio, flags)) { gup_put_folio(folio, 1, flags); goto pte_unmap; } @@ -2642,7 +2944,7 @@ static int gup_pte_range(pmd_t pmd, pmd_t *pmdp, unsigned long addr, * details. */ if (flags & FOLL_PIN) { - ret = arch_make_page_accessible(page); + ret = arch_make_folio_accessible(folio); if (ret) { gup_put_folio(folio, 1, flags); goto pte_unmap; @@ -2670,44 +2972,40 @@ pte_unmap: * * For a futex to be placed on a THP tail page, get_futex_key requires a * get_user_pages_fast_only implementation that can pin pages. Thus it's still - * useful to have gup_huge_pmd even if we can't operate on ptes. + * useful to have gup_fast_pmd_leaf even if we can't operate on ptes. */ -static int gup_pte_range(pmd_t pmd, pmd_t *pmdp, unsigned long addr, - unsigned long end, unsigned int flags, - struct page **pages, int *nr) +static int gup_fast_pte_range(pmd_t pmd, pmd_t *pmdp, unsigned long addr, + unsigned long end, unsigned int flags, struct page **pages, + int *nr) { return 0; } #endif /* CONFIG_ARCH_HAS_PTE_SPECIAL */ #if defined(CONFIG_ARCH_HAS_PTE_DEVMAP) && defined(CONFIG_TRANSPARENT_HUGEPAGE) -static int __gup_device_huge(unsigned long pfn, unsigned long addr, - unsigned long end, unsigned int flags, - struct page **pages, int *nr) +static int gup_fast_devmap_leaf(unsigned long pfn, unsigned long addr, + unsigned long end, unsigned int flags, struct page **pages, int *nr) { int nr_start = *nr; struct dev_pagemap *pgmap = NULL; do { + struct folio *folio; struct page *page = pfn_to_page(pfn); pgmap = get_dev_pagemap(pfn, pgmap); if (unlikely(!pgmap)) { - undo_dev_pagemap(nr, nr_start, flags, pages); + gup_fast_undo_dev_pagemap(nr, nr_start, flags, pages); break; } - if (!(flags & FOLL_PCI_P2PDMA) && is_pci_p2pdma_page(page)) { - undo_dev_pagemap(nr, nr_start, flags, pages); + folio = try_grab_folio_fast(page, 1, flags); + if (!folio) { + gup_fast_undo_dev_pagemap(nr, nr_start, flags, pages); break; } - - SetPageReferenced(page); + folio_set_referenced(folio); pages[*nr] = page; - if (unlikely(try_grab_page(page, flags))) { - undo_dev_pagemap(nr, nr_start, flags, pages); - break; - } (*nr)++; pfn++; } while (addr += PAGE_SIZE, addr != end); @@ -2716,175 +3014,84 @@ static int __gup_device_huge(unsigned long pfn, unsigned long addr, return addr == end; } -static int __gup_device_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr, - unsigned long end, unsigned int flags, - struct page **pages, int *nr) +static int gup_fast_devmap_pmd_leaf(pmd_t orig, pmd_t *pmdp, unsigned long addr, + unsigned long end, unsigned int flags, struct page **pages, + int *nr) { unsigned long fault_pfn; int nr_start = *nr; fault_pfn = pmd_pfn(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT); - if (!__gup_device_huge(fault_pfn, addr, end, flags, pages, nr)) + if (!gup_fast_devmap_leaf(fault_pfn, addr, end, flags, pages, nr)) return 0; if (unlikely(pmd_val(orig) != pmd_val(*pmdp))) { - undo_dev_pagemap(nr, nr_start, flags, pages); + gup_fast_undo_dev_pagemap(nr, nr_start, flags, pages); return 0; } return 1; } -static int __gup_device_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr, - unsigned long end, unsigned int flags, - struct page **pages, int *nr) +static int gup_fast_devmap_pud_leaf(pud_t orig, pud_t *pudp, unsigned long addr, + unsigned long end, unsigned int flags, struct page **pages, + int *nr) { unsigned long fault_pfn; int nr_start = *nr; fault_pfn = pud_pfn(orig) + ((addr & ~PUD_MASK) >> PAGE_SHIFT); - if (!__gup_device_huge(fault_pfn, addr, end, flags, pages, nr)) + if (!gup_fast_devmap_leaf(fault_pfn, addr, end, flags, pages, nr)) return 0; if (unlikely(pud_val(orig) != pud_val(*pudp))) { - undo_dev_pagemap(nr, nr_start, flags, pages); + gup_fast_undo_dev_pagemap(nr, nr_start, flags, pages); return 0; } return 1; } #else -static int __gup_device_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr, - unsigned long end, unsigned int flags, - struct page **pages, int *nr) +static int gup_fast_devmap_pmd_leaf(pmd_t orig, pmd_t *pmdp, unsigned long addr, + unsigned long end, unsigned int flags, struct page **pages, + int *nr) { BUILD_BUG(); return 0; } -static int __gup_device_huge_pud(pud_t pud, pud_t *pudp, unsigned long addr, - unsigned long end, unsigned int flags, - struct page **pages, int *nr) +static int gup_fast_devmap_pud_leaf(pud_t pud, pud_t *pudp, unsigned long addr, + unsigned long end, unsigned int flags, struct page **pages, + int *nr) { BUILD_BUG(); return 0; } #endif -static int record_subpages(struct page *page, unsigned long addr, - unsigned long end, struct page **pages) -{ - int nr; - - for (nr = 0; addr != end; nr++, addr += PAGE_SIZE) - pages[nr] = nth_page(page, nr); - - return nr; -} - -#ifdef CONFIG_ARCH_HAS_HUGEPD -static unsigned long hugepte_addr_end(unsigned long addr, unsigned long end, - unsigned long sz) +static int gup_fast_pmd_leaf(pmd_t orig, pmd_t *pmdp, unsigned long addr, + unsigned long end, unsigned int flags, struct page **pages, + int *nr) { - unsigned long __boundary = (addr + sz) & ~(sz-1); - return (__boundary - 1 < end - 1) ? __boundary : end; -} - -static int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr, - unsigned long end, unsigned int flags, - struct page **pages, int *nr) -{ - unsigned long pte_end; struct page *page; struct folio *folio; - pte_t pte; int refs; - pte_end = (addr + sz) & ~(sz-1); - if (pte_end < end) - end = pte_end; - - pte = huge_ptep_get(ptep); - - if (!pte_access_permitted(pte, flags & FOLL_WRITE)) - return 0; - - /* hugepages are never "special" */ - VM_BUG_ON(!pfn_valid(pte_pfn(pte))); - - page = nth_page(pte_page(pte), (addr & (sz - 1)) >> PAGE_SHIFT); - refs = record_subpages(page, addr, end, pages + *nr); - - folio = try_grab_folio(page, refs, flags); - if (!folio) - return 0; - - if (unlikely(pte_val(pte) != pte_val(ptep_get(ptep)))) { - gup_put_folio(folio, refs, flags); - return 0; - } - - if (!folio_fast_pin_allowed(folio, flags)) { - gup_put_folio(folio, refs, flags); - return 0; - } - - if (!pte_write(pte) && gup_must_unshare(NULL, flags, &folio->page)) { - gup_put_folio(folio, refs, flags); + if (!pmd_access_permitted(orig, flags & FOLL_WRITE)) return 0; - } - - *nr += refs; - folio_set_referenced(folio); - return 1; -} - -static int gup_huge_pd(hugepd_t hugepd, unsigned long addr, - unsigned int pdshift, unsigned long end, unsigned int flags, - struct page **pages, int *nr) -{ - pte_t *ptep; - unsigned long sz = 1UL << hugepd_shift(hugepd); - unsigned long next; - - ptep = hugepte_offset(hugepd, addr, pdshift); - do { - next = hugepte_addr_end(addr, end, sz); - if (!gup_hugepte(ptep, sz, addr, end, flags, pages, nr)) - return 0; - } while (ptep++, addr = next, addr != end); - - return 1; -} -#else -static inline int gup_huge_pd(hugepd_t hugepd, unsigned long addr, - unsigned int pdshift, unsigned long end, unsigned int flags, - struct page **pages, int *nr) -{ - return 0; -} -#endif /* CONFIG_ARCH_HAS_HUGEPD */ - -static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr, - unsigned long end, unsigned int flags, - struct page **pages, int *nr) -{ - struct page *page; - struct folio *folio; - int refs; - if (!pmd_access_permitted(orig, flags & FOLL_WRITE)) + if (pmd_special(orig)) return 0; if (pmd_devmap(orig)) { if (unlikely(flags & FOLL_LONGTERM)) return 0; - return __gup_device_huge_pmd(orig, pmdp, addr, end, flags, - pages, nr); + return gup_fast_devmap_pmd_leaf(orig, pmdp, addr, end, flags, + pages, nr); } - page = nth_page(pmd_page(orig), (addr & ~PMD_MASK) >> PAGE_SHIFT); - refs = record_subpages(page, addr, end, pages + *nr); + page = pmd_page(orig); + refs = record_subpages(page, PMD_SIZE, addr, end, pages + *nr); - folio = try_grab_folio(page, refs, flags); + folio = try_grab_folio_fast(page, refs, flags); if (!folio) return 0; @@ -2893,7 +3100,7 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr, return 0; } - if (!folio_fast_pin_allowed(folio, flags)) { + if (!gup_fast_folio_allowed(folio, flags)) { gup_put_folio(folio, refs, flags); return 0; } @@ -2907,9 +3114,9 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr, return 1; } -static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr, - unsigned long end, unsigned int flags, - struct page **pages, int *nr) +static int gup_fast_pud_leaf(pud_t orig, pud_t *pudp, unsigned long addr, + unsigned long end, unsigned int flags, struct page **pages, + int *nr) { struct page *page; struct folio *folio; @@ -2918,17 +3125,20 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr, if (!pud_access_permitted(orig, flags & FOLL_WRITE)) return 0; + if (pud_special(orig)) + return 0; + if (pud_devmap(orig)) { if (unlikely(flags & FOLL_LONGTERM)) return 0; - return __gup_device_huge_pud(orig, pudp, addr, end, flags, - pages, nr); + return gup_fast_devmap_pud_leaf(orig, pudp, addr, end, flags, + pages, nr); } - page = nth_page(pud_page(orig), (addr & ~PUD_MASK) >> PAGE_SHIFT); - refs = record_subpages(page, addr, end, pages + *nr); + page = pud_page(orig); + refs = record_subpages(page, PUD_SIZE, addr, end, pages + *nr); - folio = try_grab_folio(page, refs, flags); + folio = try_grab_folio_fast(page, refs, flags); if (!folio) return 0; @@ -2937,7 +3147,7 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr, return 0; } - if (!folio_fast_pin_allowed(folio, flags)) { + if (!gup_fast_folio_allowed(folio, flags)) { gup_put_folio(folio, refs, flags); return 0; } @@ -2952,48 +3162,9 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr, return 1; } -static int gup_huge_pgd(pgd_t orig, pgd_t *pgdp, unsigned long addr, - unsigned long end, unsigned int flags, - struct page **pages, int *nr) -{ - int refs; - struct page *page; - struct folio *folio; - - if (!pgd_access_permitted(orig, flags & FOLL_WRITE)) - return 0; - - BUILD_BUG_ON(pgd_devmap(orig)); - - page = nth_page(pgd_page(orig), (addr & ~PGDIR_MASK) >> PAGE_SHIFT); - refs = record_subpages(page, addr, end, pages + *nr); - - folio = try_grab_folio(page, refs, flags); - if (!folio) - return 0; - - if (unlikely(pgd_val(orig) != pgd_val(*pgdp))) { - gup_put_folio(folio, refs, flags); - return 0; - } - - if (!pgd_write(orig) && gup_must_unshare(NULL, flags, &folio->page)) { - gup_put_folio(folio, refs, flags); - return 0; - } - - if (!folio_fast_pin_allowed(folio, flags)) { - gup_put_folio(folio, refs, flags); - return 0; - } - - *nr += refs; - folio_set_referenced(folio); - return 1; -} - -static int gup_pmd_range(pud_t *pudp, pud_t pud, unsigned long addr, unsigned long end, - unsigned int flags, struct page **pages, int *nr) +static int gup_fast_pmd_range(pud_t *pudp, pud_t pud, unsigned long addr, + unsigned long end, unsigned int flags, struct page **pages, + int *nr) { unsigned long next; pmd_t *pmdp; @@ -3006,33 +3177,26 @@ static int gup_pmd_range(pud_t *pudp, pud_t pud, unsigned long addr, unsigned lo if (!pmd_present(pmd)) return 0; - if (unlikely(pmd_trans_huge(pmd) || pmd_huge(pmd) || - pmd_devmap(pmd))) { - /* See gup_pte_range() */ + if (unlikely(pmd_leaf(pmd))) { + /* See gup_fast_pte_range() */ if (pmd_protnone(pmd)) return 0; - if (!gup_huge_pmd(pmd, pmdp, addr, next, flags, + if (!gup_fast_pmd_leaf(pmd, pmdp, addr, next, flags, pages, nr)) return 0; - } else if (unlikely(is_hugepd(__hugepd(pmd_val(pmd))))) { - /* - * architecture have different format for hugetlbfs - * pmd format and THP pmd format - */ - if (!gup_huge_pd(__hugepd(pmd_val(pmd)), addr, - PMD_SHIFT, next, flags, pages, nr)) - return 0; - } else if (!gup_pte_range(pmd, pmdp, addr, next, flags, pages, nr)) + } else if (!gup_fast_pte_range(pmd, pmdp, addr, next, flags, + pages, nr)) return 0; } while (pmdp++, addr = next, addr != end); return 1; } -static int gup_pud_range(p4d_t *p4dp, p4d_t p4d, unsigned long addr, unsigned long end, - unsigned int flags, struct page **pages, int *nr) +static int gup_fast_pud_range(p4d_t *p4dp, p4d_t p4d, unsigned long addr, + unsigned long end, unsigned int flags, struct page **pages, + int *nr) { unsigned long next; pud_t *pudp; @@ -3044,23 +3208,21 @@ static int gup_pud_range(p4d_t *p4dp, p4d_t p4d, unsigned long addr, unsigned lo next = pud_addr_end(addr, end); if (unlikely(!pud_present(pud))) return 0; - if (unlikely(pud_huge(pud) || pud_devmap(pud))) { - if (!gup_huge_pud(pud, pudp, addr, next, flags, - pages, nr)) - return 0; - } else if (unlikely(is_hugepd(__hugepd(pud_val(pud))))) { - if (!gup_huge_pd(__hugepd(pud_val(pud)), addr, - PUD_SHIFT, next, flags, pages, nr)) + if (unlikely(pud_leaf(pud))) { + if (!gup_fast_pud_leaf(pud, pudp, addr, next, flags, + pages, nr)) return 0; - } else if (!gup_pmd_range(pudp, pud, addr, next, flags, pages, nr)) + } else if (!gup_fast_pmd_range(pudp, pud, addr, next, flags, + pages, nr)) return 0; } while (pudp++, addr = next, addr != end); return 1; } -static int gup_p4d_range(pgd_t *pgdp, pgd_t pgd, unsigned long addr, unsigned long end, - unsigned int flags, struct page **pages, int *nr) +static int gup_fast_p4d_range(pgd_t *pgdp, pgd_t pgd, unsigned long addr, + unsigned long end, unsigned int flags, struct page **pages, + int *nr) { unsigned long next; p4d_t *p4dp; @@ -3070,21 +3232,18 @@ static int gup_p4d_range(pgd_t *pgdp, pgd_t pgd, unsigned long addr, unsigned lo p4d_t p4d = READ_ONCE(*p4dp); next = p4d_addr_end(addr, end); - if (p4d_none(p4d)) + if (!p4d_present(p4d)) return 0; - BUILD_BUG_ON(p4d_huge(p4d)); - if (unlikely(is_hugepd(__hugepd(p4d_val(p4d))))) { - if (!gup_huge_pd(__hugepd(p4d_val(p4d)), addr, - P4D_SHIFT, next, flags, pages, nr)) - return 0; - } else if (!gup_pud_range(p4dp, p4d, addr, next, flags, pages, nr)) + BUILD_BUG_ON(p4d_leaf(p4d)); + if (!gup_fast_pud_range(p4dp, p4d, addr, next, flags, + pages, nr)) return 0; } while (p4dp++, addr = next, addr != end); return 1; } -static void gup_pgd_range(unsigned long addr, unsigned long end, +static void gup_fast_pgd_range(unsigned long addr, unsigned long end, unsigned int flags, struct page **pages, int *nr) { unsigned long next; @@ -3097,24 +3256,18 @@ static void gup_pgd_range(unsigned long addr, unsigned long end, next = pgd_addr_end(addr, end); if (pgd_none(pgd)) return; - if (unlikely(pgd_huge(pgd))) { - if (!gup_huge_pgd(pgd, pgdp, addr, next, flags, - pages, nr)) - return; - } else if (unlikely(is_hugepd(__hugepd(pgd_val(pgd))))) { - if (!gup_huge_pd(__hugepd(pgd_val(pgd)), addr, - PGDIR_SHIFT, next, flags, pages, nr)) - return; - } else if (!gup_p4d_range(pgdp, pgd, addr, next, flags, pages, nr)) + BUILD_BUG_ON(pgd_leaf(pgd)); + if (!gup_fast_p4d_range(pgdp, pgd, addr, next, flags, + pages, nr)) return; } while (pgdp++, addr = next, addr != end); } #else -static inline void gup_pgd_range(unsigned long addr, unsigned long end, +static inline void gup_fast_pgd_range(unsigned long addr, unsigned long end, unsigned int flags, struct page **pages, int *nr) { } -#endif /* CONFIG_HAVE_FAST_GUP */ +#endif /* CONFIG_HAVE_GUP_FAST */ #ifndef gup_fast_permitted /* @@ -3127,22 +3280,19 @@ static bool gup_fast_permitted(unsigned long start, unsigned long end) } #endif -static unsigned long lockless_pages_from_mm(unsigned long start, - unsigned long end, - unsigned int gup_flags, - struct page **pages) +static unsigned long gup_fast(unsigned long start, unsigned long end, + unsigned int gup_flags, struct page **pages) { unsigned long flags; int nr_pinned = 0; unsigned seq; - if (!IS_ENABLED(CONFIG_HAVE_FAST_GUP) || + if (!IS_ENABLED(CONFIG_HAVE_GUP_FAST) || !gup_fast_permitted(start, end)) return 0; if (gup_flags & FOLL_PIN) { - seq = raw_read_seqcount(¤t->mm->write_protect_seq); - if (seq & 1) + if (!raw_seqcount_try_begin(¤t->mm->write_protect_seq, seq)) return 0; } @@ -3155,19 +3305,19 @@ static unsigned long lockless_pages_from_mm(unsigned long start, * include/asm-generic/tlb.h for more details. * * We do not adopt an rcu_read_lock() here as we also want to block IPIs - * that come from THPs splitting. + * that come from callers of tlb_remove_table_sync_one(). */ local_irq_save(flags); - gup_pgd_range(start, end, gup_flags, pages, &nr_pinned); + gup_fast_pgd_range(start, end, gup_flags, pages, &nr_pinned); local_irq_restore(flags); /* * When pinning pages for DMA there could be a concurrent write protect - * from fork() via copy_page_range(), in this case always fail fast GUP. + * from fork() via copy_page_range(), in this case always fail GUP-fast. */ if (gup_flags & FOLL_PIN) { if (read_seqcount_retry(¤t->mm->write_protect_seq, seq)) { - unpin_user_pages_lockless(pages, nr_pinned); + gup_fast_unpin_user_pages(pages, nr_pinned); return 0; } else { sanity_check_pinned_pages(pages, nr_pinned); @@ -3176,10 +3326,8 @@ static unsigned long lockless_pages_from_mm(unsigned long start, return nr_pinned; } -static int internal_get_user_pages_fast(unsigned long start, - unsigned long nr_pages, - unsigned int gup_flags, - struct page **pages) +static int gup_fast_fallback(unsigned long start, unsigned long nr_pages, + unsigned int gup_flags, struct page **pages) { unsigned long len, end; unsigned long nr_pinned; @@ -3204,10 +3352,8 @@ static int internal_get_user_pages_fast(unsigned long start, return -EOVERFLOW; if (end > TASK_SIZE_MAX) return -EFAULT; - if (unlikely(!access_ok((void __user *)start, len))) - return -EFAULT; - nr_pinned = lockless_pages_from_mm(start, end, gup_flags, pages); + nr_pinned = gup_fast(start, end, gup_flags, pages); if (nr_pinned == nr_pages || gup_flags & FOLL_FAST_ONLY) return nr_pinned; @@ -3261,7 +3407,7 @@ int get_user_pages_fast_only(unsigned long start, int nr_pages, FOLL_GET | FOLL_FAST_ONLY)) return -EINVAL; - return internal_get_user_pages_fast(start, nr_pages, gup_flags, pages); + return gup_fast_fallback(start, nr_pages, gup_flags, pages); } EXPORT_SYMBOL_GPL(get_user_pages_fast_only); @@ -3292,7 +3438,7 @@ int get_user_pages_fast(unsigned long start, int nr_pages, */ if (!is_valid_gup_args(pages, NULL, &gup_flags, FOLL_GET)) return -EINVAL; - return internal_get_user_pages_fast(start, nr_pages, gup_flags, pages); + return gup_fast_fallback(start, nr_pages, gup_flags, pages); } EXPORT_SYMBOL_GPL(get_user_pages_fast); @@ -3320,7 +3466,7 @@ int pin_user_pages_fast(unsigned long start, int nr_pages, { if (!is_valid_gup_args(pages, NULL, &gup_flags, FOLL_PIN)) return -EINVAL; - return internal_get_user_pages_fast(start, nr_pages, gup_flags, pages); + return gup_fast_fallback(start, nr_pages, gup_flags, pages); } EXPORT_SYMBOL_GPL(pin_user_pages_fast); @@ -3414,3 +3560,152 @@ long pin_user_pages_unlocked(unsigned long start, unsigned long nr_pages, &locked, gup_flags); } EXPORT_SYMBOL(pin_user_pages_unlocked); + +/** + * memfd_pin_folios() - pin folios associated with a memfd + * @memfd: the memfd whose folios are to be pinned + * @start: the first memfd offset + * @end: the last memfd offset (inclusive) + * @folios: array that receives pointers to the folios pinned + * @max_folios: maximum number of entries in @folios + * @offset: the offset into the first folio + * + * Attempt to pin folios associated with a memfd in the contiguous range + * [start, end]. Given that a memfd is either backed by shmem or hugetlb, + * the folios can either be found in the page cache or need to be allocated + * if necessary. Once the folios are located, they are all pinned via + * FOLL_PIN and @offset is populatedwith the offset into the first folio. + * And, eventually, these pinned folios must be released either using + * unpin_folios() or unpin_folio(). + * + * It must be noted that the folios may be pinned for an indefinite amount + * of time. And, in most cases, the duration of time they may stay pinned + * would be controlled by the userspace. This behavior is effectively the + * same as using FOLL_LONGTERM with other GUP APIs. + * + * Returns number of folios pinned, which could be less than @max_folios + * as it depends on the folio sizes that cover the range [start, end]. + * If no folios were pinned, it returns -errno. + */ +long memfd_pin_folios(struct file *memfd, loff_t start, loff_t end, + struct folio **folios, unsigned int max_folios, + pgoff_t *offset) +{ + unsigned int flags, nr_folios, nr_found; + unsigned int i, pgshift = PAGE_SHIFT; + pgoff_t start_idx, end_idx; + struct folio *folio = NULL; + struct folio_batch fbatch; + struct hstate *h; + long ret = -EINVAL; + + if (start < 0 || start > end || !max_folios) + return -EINVAL; + + if (!memfd) + return -EINVAL; + + if (!shmem_file(memfd) && !is_file_hugepages(memfd)) + return -EINVAL; + + if (end >= i_size_read(file_inode(memfd))) + return -EINVAL; + + if (is_file_hugepages(memfd)) { + h = hstate_file(memfd); + pgshift = huge_page_shift(h); + } + + flags = memalloc_pin_save(); + do { + nr_folios = 0; + start_idx = start >> pgshift; + end_idx = end >> pgshift; + if (is_file_hugepages(memfd)) { + start_idx <<= huge_page_order(h); + end_idx <<= huge_page_order(h); + } + + folio_batch_init(&fbatch); + while (start_idx <= end_idx && nr_folios < max_folios) { + /* + * In most cases, we should be able to find the folios + * in the page cache. If we cannot find them for some + * reason, we try to allocate them and add them to the + * page cache. + */ + nr_found = filemap_get_folios_contig(memfd->f_mapping, + &start_idx, + end_idx, + &fbatch); + if (folio) { + folio_put(folio); + folio = NULL; + } + + for (i = 0; i < nr_found; i++) { + folio = fbatch.folios[i]; + + if (try_grab_folio(folio, 1, FOLL_PIN)) { + folio_batch_release(&fbatch); + ret = -EINVAL; + goto err; + } + + if (nr_folios == 0) + *offset = offset_in_folio(folio, start); + + folios[nr_folios] = folio; + if (++nr_folios == max_folios) + break; + } + + folio = NULL; + folio_batch_release(&fbatch); + if (!nr_found) { + folio = memfd_alloc_folio(memfd, start_idx); + if (IS_ERR(folio)) { + ret = PTR_ERR(folio); + if (ret != -EEXIST) + goto err; + folio = NULL; + } + } + } + + ret = check_and_migrate_movable_folios(nr_folios, folios); + } while (ret == -EAGAIN); + + memalloc_pin_restore(flags); + return ret ? ret : nr_folios; +err: + memalloc_pin_restore(flags); + unpin_folios(folios, nr_folios); + + return ret; +} +EXPORT_SYMBOL_GPL(memfd_pin_folios); + +/** + * folio_add_pins() - add pins to an already-pinned folio + * @folio: the folio to add more pins to + * @pins: number of pins to add + * + * Try to add more pins to an already-pinned folio. The semantics + * of the pin (e.g., FOLL_WRITE) follow any existing pin and cannot + * be changed. + * + * This function is helpful when having obtained a pin on a large folio + * using memfd_pin_folios(), but wanting to logically unpin parts + * (e.g., individual pages) of the folio later, for example, using + * unpin_user_page_range_dirty_lock(). + * + * This is not the right interface to initially pin a folio. + */ +int folio_add_pins(struct folio *folio, unsigned int pins) +{ + VM_WARN_ON_ONCE(!folio_maybe_dma_pinned(folio)); + + return try_grab_folio(folio, pins, FOLL_PIN); +} +EXPORT_SYMBOL_GPL(folio_add_pins); |