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t=1784530528; bh=x+kolBURkoz37XH2+zAgPHsgQcy0+7m0YaymnTdJ0PI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Qaff0VTprT/uptOom7N3m2o1wCp0o+NkCLqF5iaRvywGvdKWuFND+F0Pw1SF9HkcK 4sBQbnSEonmOtBPVtMQEGBXOPhYrB8lc8E8ijTlnnb7yULC0xYsop13Q4+CtKl3q+e 1rLTJnWy7LNGkaZLACiWro5kMo3Ygm8x9XolWf8c= From: Dev Jain To: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org Cc: Dev Jain , kasong@tencent.com, qi.zheng@linux.dev, shakeel.butt@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, riel@surriel.com, harry@kernel.org, jannh@google.com, lance.yang@linux.dev, ryan.roberts@arm.com, anshuman.khandual@arm.com Subject: [PATCH v2 1/3] mm/memory: move pte_install_uffd_wp_if_needed() into memory.c Date: Mon, 20 Jul 2026 06:55:05 +0000 Message-ID: <20260720065508.2695106-2-dev.jain@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260720065508.2695106-1-dev.jain@arm.com> References: <20260720065508.2695106-1-dev.jain@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 744641A0003 X-Stat-Signature: 7skek5d6zajx8wwqiwr46sxzeqpfssnf X-HE-Tag: 1784530529-864479 X-HE-Meta: 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 wBGhIEda 7cN3gmAzOUc0LHNgcqR4RwqEdltc3VJGbzxZZgVDlHSpyVYo4xp7JfEbsNYldJ6RJ7+73qlw+MIX6hI3RjJLWVEMzf4JL4wjAC9QgSLoqRv7rDZF1YAp5OsMtzSI8Gn1B9yZGeKknphaG5c+nmB42ATkwZ1ZD7qdiOfANrQn3gkecnlW2tsmdAMG1NGU3p7vvQ1DvRrTFEJGcAElpoS2wKA9JvcKujJiGa28bTw5s3DgujHz7YgkR/PaalvaUR/uGDAacgKTGGSyUW7EQvP+Cxlr0HXg5Q3GwPvpnCpowArgzsDI= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: pte_install_uffd_wp_if_needed() has grown too large for mm_inline.h. Move it to memory.c. This helper is only used inside mm/, so declare it in mm/internal.h instead of a public header. While at it, convert the comment to kerneldoc and rename the local arguments from pte/pteval to ptep/pte so the pointer and PTE value are easier to distinguish. Signed-off-by: Dev Jain --- include/linux/mm_inline.h | 53 ---------------------------------- mm/internal.h | 3 ++ mm/memory.c | 60 +++++++++++++++++++++++++++++++++++++++ 3 files changed, 63 insertions(+), 53 deletions(-) diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h index b5c4dc0f3fe32..621c8653d8f7e 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(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_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/internal.h b/mm/internal.h index f26423de4ca28..b6a3589a61c1a 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -276,6 +276,9 @@ void unmap_vmas(struct mmu_gather *tlb, struct unmap_desc *unmap); #ifdef CONFIG_MMU +bool pte_install_uffd_wp_if_needed(struct vm_area_struct *vma, + unsigned long addr, pte_t *ptep, pte_t pte); + static inline void get_anon_vma(struct anon_vma *anon_vma) { atomic_inc(&anon_vma->refcount); diff --git a/mm/memory.c b/mm/memory.c index d5e87624f6920..6c0c4c774674a 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1675,6 +1675,66 @@ static inline bool zap_drop_markers(struct zap_details *details) return details->zap_flags & ZAP_FLAG_DROP_MARKER; } +/** + * pte_install_uffd_wp_if_needed - install uffd-wp marker after clearing a PTE + * @vma: The VMA the page is mapped into. + * @addr: Address the page is mapped at. + * @ptep: Page table pointer for this entry. + * @pte: Old value of the entry pointed to by @ptep. + * + * If the PTE was write-protected by uffd-wp in any form, arm a special PTE + * to replace a none PTE. NOTE! This should only be called when the PTE is + * already cleared so we will never accidentally replace something valuable. + * Meanwhile none PTEs also mean we are not demoting the PTE so a TLB flush is + * not needed. E.g., when the PTE was cleared, the caller should have taken care + * of the TLB flush. + * + * Must be called with the page table lock held so that no thread will see the + * none PTE, and if they see it, they'll fault and serialize at the page table + * lock. + * + * Returns true if an uffd-wp PTE was installed, false otherwise. + */ +bool pte_install_uffd_wp_if_needed(struct vm_area_struct *vma, + unsigned long addr, pte_t *ptep, pte_t pte) +{ + 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(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_any(pte))) + arm_uffd_pte = true; + + if (unlikely(arm_uffd_pte)) { + set_pte_at(vma->vm_mm, addr, ptep, + make_pte_marker(PTE_MARKER_UFFD_WP)); + return true; + } + + return false; +} + /* * 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. -- 2.43.0