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h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=b6+PS95BFzLUjvFSdizyN/iTJgGePZWWNKL7DzMAc+OfVgATLlrKI08QXy64iceAK XgPjoTcY6qT13gn1dOcGbCFa2UQa0W6IqGGg+D5l5PHTNCCZjqioviSd7oopUC5FqV SdLSw1d9FJ0kuBbPlvxMvfWsxe272DAdl+3S+srU= From: Dev Jain To: akpm@linux-foundation.org, david@kernel.org, hughd@google.com, chrisl@kernel.org Cc: ljs@kernel.org, Liam.Howlett@oracle.com, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, kasong@tencent.com, qi.zheng@linux.dev, shakeel.butt@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, riel@surriel.com, harry@kernel.org, jannh@google.com, pfalcato@suse.de, baolin.wang@linux.alibaba.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, bhe@redhat.com, youngjun.park@lge.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, ryan.roberts@arm.com, anshuman.khandual@arm.com, Dev Jain Subject: [PATCH v2 4/9] mm/memory: Batch set uffd-wp markers during zapping Date: Fri, 10 Apr 2026 16:01:59 +0530 Message-Id: <20260410103204.120409-5-dev.jain@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260410103204.120409-1-dev.jain@arm.com> References: <20260410103204.120409-1-dev.jain@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: A1056100002 X-Stat-Signature: cj1pwek5u43nk34ysr45qno9q1aewj1n X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1775817176-505094 X-HE-Meta: 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 09ofPJS4 vAx0LZkihNoo7HkmAjl+feiT+jD6lDPPsfuQoCARAQ9VxY6pshqOCXYNx52FgOR+PXWlWnmQGgIMENNq3IEFLzoOZgcT+Hv7GFeYAsSj+FtHQ+3VA9+ZfSPX/B23+bMCFY3DrftytecIBqGeyPFMGdyQW2YS2UgWtV7V1G7m03409vw3Z8CIyGX8qC+kaKzCL2JbxxXczEkujGm3S7cDWEE15ggol4rSZLAJ9pc9uV7dhouzNuRCZJiU1TA== 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, 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 | 32 ++++++++++++++++++++------------ mm/memory.c | 20 +------------------- mm/rmap.c | 2 +- 3 files changed, 22 insertions(+), 32 deletions(-) diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h index a171070e15f05..20c34d14ad539 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 *pte, pte_t pteval, unsigned long nr_ptes) { bool arm_uffd_pte = false; @@ -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, ++pte, addr += PAGE_SIZE) + set_pte_at(vma->vm_mm, addr, pte, 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 ea65685711311..eef144fa293d4 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1594,29 +1594,11 @@ 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 fa5d6599dedf0..20e1fb81c33fc 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -2263,7 +2263,7 @@ 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