From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id B11833B3C15 for ; Mon, 20 Jul 2026 06:55:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784530538; cv=none; b=EsJPxy9B6Lcu31vVUhxPDxzku1+heGE0qRBzbpGrqBrUBkqzCbEAEd0LyFoW8ha17Kvn4txBjZ1b18XHGZEsL6VCovMbcUlqCsWzt4UDt8fjCiTvQSS26KGE6VbRTwJ/eqGVfvnpXyQ2sQ5r0GKa3riv78SR3fzxBSiFGwlFD0g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784530538; c=relaxed/simple; bh=ked3BDcGYDpvXw7eNGYa4GCDwM9ERmQ/SIgaGlKW6Ck=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Mas+DrVnXLvLsXMbkDfOi064pni0+RPiCk0rY1lk6eXxwsC5c8i8ureIsXbfQaWTyhQ9Ex0Oy/m28jLW9pNzVScFOD9TNH9qvkb/d6R/Jvfl+m0/0vdl2SLadnEAatK1PE9cCO0h4zaBGtJ0xwNTcuQRGCTtUakrvy75B6JqvBc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=LFg3vQ0z; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="LFg3vQ0z" 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 E81A61476; Sun, 19 Jul 2026 23:55:30 -0700 (PDT) Received: from cesw-amp-gbt-1s-m12830-01.blr.arm.com (cesw-amp-gbt-1s-m12830-01.blr.arm.com [10.164.195.33]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 050FD3F66F; Sun, 19 Jul 2026 23:55:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1784530535; bh=ked3BDcGYDpvXw7eNGYa4GCDwM9ERmQ/SIgaGlKW6Ck=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LFg3vQ0zClOXjP/YUj6Ru9ICRSn7R1j2oqc4shwEXq3xguWXJodF6dFMpacxMyFGc pz/BCAWzVAGCiG+GAGZLNhsWmUkDYrTRnW+lnnfD2t7IRdELSniFNhjpuDPZIL11dI JNFPa9hnzLEBCDSVV+JinCyuAVIxGA1op3SJ2GhY= 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 2/3] mm/memory: batch set uffd-wp markers during zapping Date: Mon, 20 Jul 2026 06:55:06 +0000 Message-ID: <20260720065508.2695106-3-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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Enable batch setting of uffd-wp PTE markers. 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 are either marked with uffd-wp or not marked with uffd-wp; the same applies to the pte_swp_uffd_any() check. 3) uffd_supports_wp_marker() is independent of the function parameters. Use set_pte_at() in a loop instead of set_ptes(), because set_ptes() cannot handle nonpresent to nonpresent conversion for nr_pages > 1. Rename the helper to cond_install_uffd_wp_ptes(). Signed-off-by: Dev Jain --- mm/internal.h | 5 +++-- mm/memory.c | 61 +++++++++++++++++++++------------------------------ mm/rmap.c | 2 +- 3 files changed, 29 insertions(+), 39 deletions(-) diff --git a/mm/internal.h b/mm/internal.h index b6a3589a61c1a..0f49cff67a2b8 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -276,8 +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); +bool cond_install_uffd_wp_ptes(struct vm_area_struct *vma, + unsigned long addr, pte_t *ptep, pte_t pte, + unsigned long nr_ptes); static inline void get_anon_vma(struct anon_vma *anon_vma) { diff --git a/mm/memory.c b/mm/memory.c index 6c0c4c774674a..d2f14ba2261cd 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1676,27 +1676,29 @@ static inline bool zap_drop_markers(struct zap_details *details) } /** - * 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. + * cond_install_uffd_wp_ptes - install uffd-wp markers after clearing PTEs + * @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 install. * - * 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 + * If the PTEs were write-protected by uffd-wp in any form, arm special PTEs + * to replace none PTEs. NOTE! This should only be called when the PTEs are * 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. + * Meanwhile none PTEs also mean we are not demoting the PTEs so a TLB flush is + * not needed. E.g., when the PTEs were 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 + * none PTEs, and if they see them, they'll fault and serialize at the page table * lock. * - * Returns true if an uffd-wp PTE was installed, false otherwise. + * Returns true if uffd-wp PTEs were 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 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; @@ -1726,13 +1728,19 @@ bool pte_install_uffd_wp_if_needed(struct vm_area_struct *vma, if (unlikely(pte_swp_uffd_any(pte))) arm_uffd_pte = true; - if (unlikely(arm_uffd_pte)) { + if (likely(!arm_uffd_pte)) + return false; + + for (;;) { set_pte_at(vma->vm_mm, addr, ptep, make_pte_marker(PTE_MARKER_UFFD_WP)); - return true; + if (--nr_ptes == 0) + break; + ptep++; + addr += PAGE_SIZE; } - return false; + return true; } /* @@ -1746,29 +1754,10 @@ 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 was_installed; + return cond_install_uffd_wp_ptes(vma, addr, pte, pteval, nr); } static __always_inline void zap_present_folio_ptes(struct mmu_gather *tlb, diff --git a/mm/rmap.c b/mm/rmap.c index 73c2fe2d19462..abeb8e7ceba17 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -2348,7 +2348,7 @@ 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); -- 2.43.0