In preparation for the next patch, enable batch setting of uffd-wp ptes. The code paths passing nr > 1 to zap_install_uffd_wp_if_needed() produce that nr through either folio_pte_batch or swap_pte_batch, guaranteeing that all ptes are the same w.r.t belonging to the same type of VMA (anonymous or non-anonymous, wp-armed or non-wp-armed), and all being marked with uffd-wp or all being not marked. Note that we will have to use set_pte_at() in a loop instead of set_ptes() since the latter cannot handle present->non-present conversion for nr_pages > 1. Convert documentation of install_uffd_wp_ptes_if_needed to kerneldoc format. No functional change is intended. Signed-off-by: Dev Jain --- include/linux/mm_inline.h | 34 +++++++++++++++++++++------------- mm/memory.c | 20 +------------------- mm/rmap.c | 2 +- 3 files changed, 23 insertions(+), 33 deletions(-) diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h index a171070e15f05..6f7ecede2fb45 100644 --- a/include/linux/mm_inline.h +++ b/include/linux/mm_inline.h @@ -566,9 +566,17 @@ static inline pte_marker copy_pte_marker( return dstm; } -/* - * If this pte is wr-protected by uffd-wp in any form, arm the special pte to - * replace a none pte. NOTE! This should only be called when *pte is already +/** + * install_uffd_wp_ptes_if_needed - install uffd-wp marker on PTEs that map + * consecutive pages of the same large folio. + * @vma: The VMA the pages are mapped into. + * @addr: Address the first page of this batch is mapped at. + * @ptep: Page table pointer for the first entry of this batch. + * @pteval: old value of the entry pointed to by ptep. + * @nr_ptes: Number of entries to clear (batch size). + * + * If the ptes were wr-protected by uffd-wp in any form, arm special ptes to + * replace none ptes. NOTE! This should only be called when *pte is already * cleared so we will never accidentally replace something valuable. Meanwhile * none pte also means we are not demoting the pte so tlb flushed is not needed. * E.g., when pte cleared the caller should have taken care of the tlb flush. @@ -576,11 +584,11 @@ static inline pte_marker copy_pte_marker( * Must be called with pgtable lock held so that no thread will see the none * pte, and if they see it, they'll fault and serialize at the pgtable lock. * - * Returns true if an uffd-wp pte was installed, false otherwise. + * Returns true if uffd-wp ptes were installed, false otherwise. */ static inline bool -pte_install_uffd_wp_if_needed(struct vm_area_struct *vma, unsigned long addr, - pte_t *pte, pte_t pteval) +install_uffd_wp_ptes_if_needed(struct vm_area_struct *vma, unsigned long addr, + pte_t *ptep, pte_t pteval, unsigned long nr_ptes) { bool arm_uffd_pte = false; @@ -588,7 +596,7 @@ pte_install_uffd_wp_if_needed(struct vm_area_struct *vma, unsigned long addr, return false; /* The current status of the pte should be "cleared" before calling */ - WARN_ON_ONCE(!pte_none(ptep_get(pte))); + WARN_ON_ONCE(!pte_none(ptep_get(ptep))); /* * NOTE: userfaultfd_wp_unpopulated() doesn't need this whole @@ -610,13 +618,13 @@ pte_install_uffd_wp_if_needed(struct vm_area_struct *vma, unsigned long addr, if (unlikely(pte_swp_uffd_wp_any(pteval))) arm_uffd_pte = true; - if (unlikely(arm_uffd_pte)) { - set_pte_at(vma->vm_mm, addr, pte, - make_pte_marker(PTE_MARKER_UFFD_WP)); - return true; - } + if (likely(!arm_uffd_pte)) + return false; - return false; + for (int i = 0; i < nr_ptes; ++i, ++ptep, addr += PAGE_SIZE) + set_pte_at(vma->vm_mm, addr, ptep, make_pte_marker(PTE_MARKER_UFFD_WP)); + + return true; } static inline bool vma_has_recency(const struct vm_area_struct *vma) diff --git a/mm/memory.c b/mm/memory.c index 0c9d9c2cbf0e0..f14311c4d2001 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1610,29 +1610,11 @@ zap_install_uffd_wp_if_needed(struct vm_area_struct *vma, unsigned long addr, pte_t *pte, int nr, struct zap_details *details, pte_t pteval) { - bool was_installed = false; - - if (!uffd_supports_wp_marker()) - return false; - - /* Zap on anonymous always means dropping everything */ - if (vma_is_anonymous(vma)) - return false; - if (zap_drop_markers(details)) return false; - for (;;) { - /* the PFN in the PTE is irrelevant. */ - if (pte_install_uffd_wp_if_needed(vma, addr, pte, pteval)) - was_installed = true; - if (--nr == 0) - break; - pte++; - addr += PAGE_SIZE; - } + return install_uffd_wp_ptes_if_needed(vma, addr, pte, pteval, nr); - return was_installed; } static __always_inline void zap_present_folio_ptes(struct mmu_gather *tlb, diff --git a/mm/rmap.c b/mm/rmap.c index bd4e3639e26ed..b17dce752a1ea 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -2266,7 +2266,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, * we may want to replace a none pte with a marker pte if * it's file-backed, so we don't lose the tracking info. */ - pte_install_uffd_wp_if_needed(vma, address, pvmw.pte, pteval); + install_uffd_wp_ptes_if_needed(vma, address, pvmw.pte, pteval, 1); /* Update high watermark before we lower rss */ update_hiwater_rss(mm); -- 2.34.1