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 2FA763A5448 for ; Wed, 6 May 2026 09:45:54 +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=1778060755; cv=none; b=bQETAjBaYPdtdp5KRB272a0PSxDCBCSrtr7P2KjKbBWC2m4SJj2imSokwhh6ai9Gq5Po+h0uqahXoxxjVwqgaZZCRPxK1C2LlyiD1+M9Op8MyfuVSDmmFzNqbO8WlLlAuqvLxGr+t2izK9GzEqvi8CFTaJy+ibgGlW8BIXJp2Jc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778060755; c=relaxed/simple; bh=3HkEN59qGwA9AEBO9cGzUKiZcsljeK+wx7Sw5pbA9Iw=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=lW6wq6/VekW58SrxtNxBPMrIh2wJBJ6dZUJPCvHfJGdtd8bOAwrnp9y2n0Y3H4XuDKxyJyqvYHmHms8rBQ+yRyyKEZfL6YVsCOug4YmxTfTSUfOMAPOxExWYI5/Ae6aUHjuTAuUTD59TgT0qxr0O6K9iIUnCrUEDI+ckuRCfzFU= 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=jPrZ/bLc; 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="jPrZ/bLc" 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 39B94337D; Wed, 6 May 2026 02:45:48 -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 A6BFB3F7B4; Wed, 6 May 2026 02:45:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1778060753; bh=3HkEN59qGwA9AEBO9cGzUKiZcsljeK+wx7Sw5pbA9Iw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jPrZ/bLcoYOFivLtwCgE8lA9g7fjdUB+WrnEtiShUM3iRN6TrCP8+23mIRR1wzsgB QjAGMDabR/gCPHALCB+HRvCgQP16I7KDKv7EtkhwP3Xxfxhj9vyErTYs2jDEv014DU K7xHxaq2jmZQQfuJt2E/BYS9COTBj2Z2tIWj2o3U= From: Dev Jain To: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, hughd@google.com, chrisl@kernel.org, kasong@tencent.com Cc: Dev Jain , riel@surriel.com, liam@infradead.org, vbabka@kernel.org, harry@kernel.org, jannh@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, qi.zheng@linux.dev, shakeel.butt@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, rppt@kernel.org, surenb@google.com, mhocko@suse.com, baolin.wang@linux.alibaba.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, bhe@redhat.com, youngjun.park@lge.com, pfalcato@suse.de, ryan.roberts@arm.com, anshuman.khandual@arm.com Subject: [PATCH v3 4/9] mm/memory: Batch set uffd-wp markers during zapping Date: Wed, 6 May 2026 15:14:59 +0530 Message-Id: <20260506094504.2588857-5-dev.jain@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260506094504.2588857-1-dev.jain@arm.com> References: <20260506094504.2588857-1-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 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 | 34 +++++++++++++++++++++------------- mm/memory.c | 20 +------------------- mm/rmap.c | 2 +- 3 files changed, 23 insertions(+), 33 deletions(-) diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h index a171070e15f05..6f7ecede2fb45 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 *ptep, pte_t pteval, unsigned long nr_ptes) { bool arm_uffd_pte = false; @@ -588,7 +596,7 @@ pte_install_uffd_wp_if_needed(struct vm_area_struct *vma, unsigned long addr, return false; /* The current status of the pte should be "cleared" before calling */ - WARN_ON_ONCE(!pte_none(ptep_get(pte))); + WARN_ON_ONCE(!pte_none(ptep_get(ptep))); /* * NOTE: userfaultfd_wp_unpopulated() doesn't need this whole @@ -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, ++ptep, addr += PAGE_SIZE) + set_pte_at(vma->vm_mm, addr, ptep, 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 0c9d9c2cbf0e0..f14311c4d2001 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1610,29 +1610,11 @@ 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 bd4e3639e26ed..b17dce752a1ea 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -2266,7 +2266,7 @@ 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