From nobody Sat Jul 25 02:57:49 2026 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 7ACE33B3C15 for ; Mon, 20 Jul 2026 06:55:28 +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=1784530531; cv=none; b=mObEtIeBEbAmk4b/f71ywqH9Mh5xjr7hCo82p7HA14SNHbo2mJMGYzD5IdJFs9Yz0bD3MT23vZqmgl7bLkxWHOc3Hmh7YVrGAI4hZkVEwlcO/iCRGNFKdsX0kTnKmmhqO/pozCHfp9mc211q8ay4XX2WUs8ma8JEHg5XPJhYh2Q= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784530531; c=relaxed/simple; bh=x+kolBURkoz37XH2+zAgPHsgQcy0+7m0YaymnTdJ0PI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=t8QuC/tfjAupfllNqix/ZFcVzsrCoBehWgyj0/K5dyk7YTkxcfaGTBYTQNJOZag1Cf/xYl6acOsOqCgkP+7+PHCiP0eIZB7WRWatRais0VWgylecn/nZdyrrSGL0EMo4SRw6SnR4+kGcMiOrG7XA25N81DT7AwHR8ejtwQqS5Y0= 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=Qaff0VTp; 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="Qaff0VTp" 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 3E8031516; Sun, 19 Jul 2026 23:55:24 -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 4F27E3F66F; Sun, 19 Jul 2026 23:55:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; 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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 Acked-by: David Hildenbrand (Arm) --- 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; } =20 -/* - * 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 alr= eady - * cleared so we will never accidentally replace something valuable. Mean= while - * none pte also means we are not demoting the pte so tlb flushed is not n= eeded. - * E.g., when pte cleared the caller should have taken care of the tlb flu= sh. - * - * Must be called with pgtable lock held so that no thread will see the no= ne - * pte, and if they see it, they'll fault and serialize at the pgtable loc= k. - * - * 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 ad= dr, - pte_t *pte, pte_t pteval) -{ - bool arm_uffd_pte =3D 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 =3D 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 =3D 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_de= sc *unmap); =20 #ifdef CONFIG_MMU =20 +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_detai= ls *details) return details->zap_flags & ZAP_FLAG_DROP_MARKER; } =20 +/** + * 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 valuabl= e. + * Meanwhile none PTEs also mean we are not demoting the PTE so a TLB flus= h is + * not needed. E.g., when the PTE was cleared, the caller should have take= n 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 t= able + * 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 =3D 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 =3D 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 =3D 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 h= eld. --=20 2.43.0 From nobody Sat Jul 25 02:57:49 2026 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: quoted-printable Content-Type: text/plain; charset="utf-8" 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 Acked-by: David Hildenbrand (Arm) --- 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_de= sc *unmap); =20 #ifdef CONFIG_MMU =20 -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); =20 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_deta= ils *details) } =20 /** - * 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 PT= Es + * to replace none PTEs. NOTE! This should only be called when the PTEs are * already cleared so we will never accidentally replace something valuabl= e. - * Meanwhile none PTEs also mean we are not demoting the PTE so a TLB flus= h is - * not needed. E.g., when the PTE was cleared, the caller should have take= n care - * of the TLB flush. + * Meanwhile none PTEs also mean we are not demoting the PTEs so a TLB flu= sh is + * not needed. E.g., when the PTEs were cleared, the caller should have ta= ken + * 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 t= able + * none PTEs, and if they see them, they'll fault and serialize at the pag= e 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 =3D false; =20 @@ -1726,13 +1728,19 @@ bool pte_install_uffd_wp_if_needed(struct vm_area_s= truct *vma, if (unlikely(pte_swp_uffd_any(pte))) arm_uffd_pte =3D true; =20 - 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 =3D=3D 0) + break; + ptep++; + addr +=3D PAGE_SIZE; } =20 - return false; + return true; } =20 /* @@ -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 =3D 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; =20 - for (;;) { - /* the PFN in the PTE is irrelevant. */ - if (pte_install_uffd_wp_if_needed(vma, addr, pte, pteval)) - was_installed =3D true; - if (--nr =3D=3D 0) - break; - pte++; - addr +=3D PAGE_SIZE; - } - - return was_installed; + return cond_install_uffd_wp_ptes(vma, addr, pte, pteval, nr); } =20 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, str= uct 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); =20 /* Update high watermark before we lower rss */ update_hiwater_rss(mm); --=20 2.43.0 From nobody Sat Jul 25 02:57:49 2026 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 4725F3B3BF5 for ; Mon, 20 Jul 2026 06:55:42 +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=1784530544; cv=none; b=hJA8EE1qmeh69dVw5uPv4r6woSW7SZ0lbcieoRqR5+PAnnSTzezdCg5T73k+nAeLj2eaFox6P7MyMs3YBlLNFS+D1xYrtFfdJCJThtvTwHfrV0mkkQuL21ulQOBLFr6wOdX6dtZgKtlR8U7INFIzeWxvbkgZR77NnFEY4vSCM2g= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784530544; c=relaxed/simple; bh=0uZCBLA/6tv50+Xe48dX0mngoeuzlIGQwQYeLrBh4lY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=iq8xrbOUDcclKRUeAxF4Sf0UolK3v3lMa4L2bS0xh3OGmLnFugU0PPxA0kARBCFNeIZq/qVreEyn0Za29wtZ8LomYta6AYu8ckeulMyKoqJeR47//OO0cDigEaougHoKgZzvvoCOm0Q9+9/aQ0km6yNt5lzIfyYfIMilFNGWSu8= ARC-Authentication-Results: i=1; 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t=1784530541; bh=0uZCBLA/6tv50+Xe48dX0mngoeuzlIGQwQYeLrBh4lY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=H0xKn+bngtg4BLC2D/vhC7e1XPwe1FrLhGweIhhaXrq2APRtiYOJ14I9r9//8gzcK VUZh22RAI1Mvb8nWOKXE3O+LDiw4sx1GDF+N2MKUILSHon9gU06tmW5csVccIFD84P 2GFw2+TaofMRBayEIOFWiv0g5QJXEjDCFkhZEMnQ= 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 3/3] mm/rmap: batch unmap file folios belonging to uffd-wp VMAs Date: Mon, 20 Jul 2026 06:55:07 +0000 Message-ID: <20260720065508.2695106-4-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: quoted-printable Content-Type: text/plain; charset="utf-8" Commit a67fe41e214f ("mm: rmap: support batched unmapping for file large folios") extended batched unmapping for file folios. That also required making pte_install_uffd_wp_if_needed() support batching, but that was left out for the time being. Correctness was maintained by stopping batching if the VMA the folio belongs to is marked uffd-wp. Now that cond_install_uffd_wp_ptes() supports batching, call it with the full batch length and allow folio_unmap_pte_batch() to batch file folios belonging to uffd-wp VMAs. For file folios, if the uffd-wp bit is set, unmapping converts present PTEs into uffd-wp markers. We must ensure that the same PTE range is not reprocessed by the try_to_unmap_one() loop. The page_vma_mapped_walk API ensures this: check_pte() only returns true if any PFN in [pvmw->pfn, pvmw->pfn + nr_pages) is mapped by the PTE. There is no PFN underlying a uffd-wp marker PTE, so check_pte() returns false and the walk skips ahead until it reaches a present entry again. Acked-by: David Hildenbrand (Arm) Signed-off-by: Dev Jain --- mm/rmap.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/mm/rmap.c b/mm/rmap.c index abeb8e7ceba17..56eaddfc610b1 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1968,9 +1968,6 @@ static inline unsigned int folio_unmap_pte_batch(stru= ct folio *folio, if (pte_unused(pte)) return 1; =20 - if (userfaultfd_protected(vma)) - return 1; - /* * If unmap fails, we need to restore the ptes. To avoid accidentally * upgrading write permissions for ptes that were not originally @@ -2348,7 +2345,8 @@ static bool try_to_unmap_one(struct folio *folio, str= uct 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. */ - cond_install_uffd_wp_ptes(vma, address, pvmw.pte, pteval, 1); + cond_install_uffd_wp_ptes(vma, address, pvmw.pte, pteval, + nr_pages); =20 /* Update high watermark before we lower rss */ update_hiwater_rss(mm); --=20 2.43.0