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h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ixieteNT5AHRreFsKcE8P0vQ1MhVjUa9aWKpq7LXhzzWKF7m9BufjxIQnMhHIhZId kZ248APRVGyJ+RKaf3O2CKfRkeF7hnVHu/MhtmAKGE7SycI9p8uJL+EX35NzhynWNU XqLgKTS4Bhd5twszpcS5UTZPpbPKJ064cL/ihVcM= From: Dev Jain To: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, chrisl@kernel.org, kasong@tencent.com, hughd@google.com, liam@infradead.org Cc: Dev Jain , riel@surriel.com, vbabka@kernel.org, harry@kernel.org, jannh@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, qi.zheng@linux.dev, shakeel.butt@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, bhe@redhat.com, youngjun.park@lge.com, baolin.wang@linux.alibaba.com, pfalcato@suse.de, ryan.roberts@arm.com, anshuman.khandual@arm.com Subject: [PATCH v4 04/12] mm/memory: Batch set uffd-wp markers during zapping Date: Tue, 26 May 2026 12:06:27 +0530 Message-Id: <20260526063635.61721-5-dev.jain@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260526063635.61721-1-dev.jain@arm.com> References: <20260526063635.61721-1-dev.jain@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: B9AEB100005 X-Stat-Signature: gw9et3gdxcibgaipegqrxy7jyp5xsu76 X-Rspamd-Server: rspam06 X-HE-Tag: 1779777455-70828 X-HE-Meta: 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 DVBoflNM cqrDAGfJ995nahbu5ioh0+189K17MnjhMW0KQQd4ShxjoJp6BqmdiLOPT0ys3xr0Vj0OSDF5IkJx2n/G+FN6fmaWF6qPOdUU466wq3+TjRsElqKhCPk9pFnAczj0Rn92KMrYkuLVfV/8mrxlrze7TSjGBGdyItMtPvHPbxq3D/ITT7IjMiG1vGW3Fby3wn/xX0H0EKLRuD1M2QoQpnUUbtTDLhvgSVpgsrO2+Ea9Qr/ogzGkRhWlA3sirdTUHBMORaQKWsXLepkCX59iyvTyWP46Zgg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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, therefore batching is correct: 1) all ptes belong to the same type of VMA (anonymous or non-anonymous, wp-armed or non-wp-armed) 2) all ptes being marked with uffd-wp or all being not marked (same is the case with the pte_swp_uffd_wp_any check) 3) uffd_supports_wp_marker() is independent of the function parameters 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. Rename the function to cond_install_uffd_wp_ptes, and convert the documentation to kerneldoc format. Move the function to memory.c since this has grown too long to be kept in mm_inline.h, while retaining the inline hint. Rename pte->ptep and pteval->pte. Signed-off-by: Dev Jain --- include/linux/mm.h | 4 ++ include/linux/mm_inline.h | 53 ------------------------- mm/memory.c | 81 ++++++++++++++++++++++++++++++--------- mm/rmap.c | 2 +- 4 files changed, 67 insertions(+), 73 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 31e27ff6a35fa..3169bd6d69f5a 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -5216,4 +5216,8 @@ void map_anon_folio_pte_nopf(struct folio *folio, pte_t *pte, struct vm_area_struct *vma, unsigned long addr, bool uffd_wp); +bool cond_install_uffd_wp_ptes(struct vm_area_struct *vma, unsigned long addr, + pte_t *ptep, pte_t pte, unsigned long nr_ptes); + + #endif /* _LINUX_MM_H */ diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h index a171070e15f05..1a65c2bda2398 100644 --- a/include/linux/mm_inline.h +++ b/include/linux/mm_inline.h @@ -566,59 +566,6 @@ 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 - * 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. - * - * 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. - */ -static inline bool -pte_install_uffd_wp_if_needed(struct vm_area_struct *vma, unsigned long addr, - pte_t *pte, pte_t pteval) -{ - bool arm_uffd_pte = false; - - if (!uffd_supports_wp_marker()) - return false; - - /* The current status of the pte should be "cleared" before calling */ - WARN_ON_ONCE(!pte_none(ptep_get(pte))); - - /* - * NOTE: userfaultfd_wp_unpopulated() doesn't need this whole - * thing, because when zapping either it means it's dropping the - * page, or in TTU where the present pte will be quickly replaced - * with a swap pte. There's no way of leaking the bit. - */ - if (vma_is_anonymous(vma) || !userfaultfd_wp(vma)) - return false; - - /* A uffd-wp wr-protected normal pte */ - if (unlikely(pte_present(pteval) && pte_uffd_wp(pteval))) - arm_uffd_pte = true; - - /* - * A uffd-wp wr-protected swap pte. Note: this should even cover an - * existing pte marker with uffd-wp bit set. - */ - 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; - } - - return false; -} - static inline bool vma_has_recency(const struct vm_area_struct *vma) { if (vma->vm_flags & (VM_SEQ_READ | VM_RAND_READ)) diff --git a/mm/memory.c b/mm/memory.c index 0c9d9c2cbf0e0..767c033e95da9 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1599,6 +1599,67 @@ static inline bool zap_drop_markers(struct zap_details *details) return details->zap_flags & ZAP_FLAG_DROP_MARKER; } +/** + * cond_install_uffd_wp_ptes - install uffd-wp marker after clearing PTEs + * that mapped 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. + * @pte: 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. + * + * 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 uffd-wp ptes were installed, false otherwise. + */ +inline bool cond_install_uffd_wp_ptes(struct vm_area_struct *vma, unsigned long addr, + pte_t *ptep, pte_t pte, unsigned long nr_ptes) +{ + bool arm_uffd_pte = false; + + if (!uffd_supports_wp_marker()) + return false; + + /* The current status of the pte should be "cleared" before calling */ + WARN_ON_ONCE(!pte_none(ptep_get(ptep))); + + /* + * NOTE: userfaultfd_wp_unpopulated() doesn't need this whole + * thing, because when zapping either it means it's dropping the + * page, or in TTU where the present pte will be quickly replaced + * with a swap pte. There's no way of leaking the bit. + */ + if (vma_is_anonymous(vma) || !userfaultfd_wp(vma)) + return false; + + /* A uffd-wp wr-protected normal pte */ + if (unlikely(pte_present(pte) && pte_uffd_wp(pte))) + arm_uffd_pte = true; + + /* + * A uffd-wp wr-protected swap pte. Note: this should even cover an + * existing pte marker with uffd-wp bit set. + */ + if (unlikely(pte_swp_uffd_wp_any(pte))) + arm_uffd_pte = true; + + if (likely(!arm_uffd_pte)) + 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; +} + /* * This function makes sure that we'll replace the none pte with an uffd-wp * swap special pte marker when necessary. Must be with the pgtable lock held. @@ -1610,29 +1671,11 @@ 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 cond_install_uffd_wp_ptes(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 12bbee57f20da..6a0b43856d6c0 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -2288,7 +2288,7 @@ 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); + cond_install_uffd_wp_ptes(vma, address, pvmw.pte, pteval, 1); /* Update high watermark before we lower rss */ update_hiwater_rss(mm); -- 2.34.1