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imf26.hostedemail.com; dkim=none; spf=pass (imf26.hostedemail.com: domain of dev.jain@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=dev.jain@arm.com; dmarc=pass (policy=none) header.from=arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1773127884; a=rsa-sha256; cv=none; b=kKqSxKLeMt/L9AuPbQVW09jcvNHhmh19AuAYisfL85DcH0bCGziyKqq63fPnRxPEolzvL/ oAn+f3eXConZ/EHiwof/XzLT1rzkUFbR6Yj9PBokidlbnweDY6QNI8N0jJl0cBErg2+L/W BfPONES4CEHOg3NDk9qtxRqSoM71IBQ= Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A178A1756; Tue, 10 Mar 2026 00:31:17 -0700 (PDT) Received: from a080796.blr.arm.com (a080796.arm.com [10.164.21.51]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 075CF3F73B; Tue, 10 Mar 2026 00:31:14 -0700 (PDT) From: Dev Jain To: akpm@linux-foundation.org, axelrasmussen@google.com, yuanchu@google.com, david@kernel.org, hughd@google.com, chrisl@kernel.org, kasong@tencent.com Cc: weixugc@google.com, ljs@kernel.org, Liam.Howlett@oracle.com, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, riel@surriel.com, harry.yoo@oracle.com, jannh@google.com, pfalcato@suse.de, baolin.wang@linux.alibaba.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, bhe@redhat.com, baohua@kernel.org, youngjun.park@lge.com, ziy@nvidia.com, kas@kernel.org, willy@infradead.org, yuzhao@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, ryan.roberts@arm.com, anshuman.khandual@arm.com, Dev Jain Subject: [PATCH 4/9] mm/memory: Batch set uffd-wp markers during zapping Date: Tue, 10 Mar 2026 13:00:08 +0530 Message-Id: <20260310073013.4069309-5-dev.jain@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260310073013.4069309-1-dev.jain@arm.com> References: <20260310073013.4069309-1-dev.jain@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 95411140007 X-Stat-Signature: b8ub9pk9xy3cmg9umasm45htke69myt9 X-Rspam-User: X-Rspamd-Server: rspam05 X-HE-Tag: 1773127884-107548 X-HE-Meta: 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 NWPeLWVu Onety37WBGs8qdghaBYZ8JT1AWgparqquKKh3JIpkFXQ5EjqlilXr6+QjYbZvNz07kjDrPGfiAhGzADFD0W3tySJN47GeWMq4aPOIEtWR0bhPLAgsicnbpt0jEA== 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 | 37 +++++++++++++++++++++++-------------- mm/memory.c | 20 +------------------- mm/rmap.c | 2 +- 3 files changed, 25 insertions(+), 34 deletions(-) diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h index ad50688d89dba..d69b9abbdf2a7 100644 --- a/include/linux/mm_inline.h +++ b/include/linux/mm_inline.h @@ -560,21 +560,30 @@ 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: 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. + * Context: The caller holds the page table lock. The PTEs map consecutive + * pages that belong to the same folio. The PTEs are all in the same PMD + * and the same VMA. * - * 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 int nr) { bool arm_uffd_pte = false; @@ -604,13 +613,13 @@ 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; ++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 38062f8e11656..768646c0b3b6a 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 a61978141ee3f..a7570cd037344 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -2235,7 +2235,7 @@ 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