From nobody Sat Jul 25 17:33:42 2026 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id A1B6B3164C5 for ; Wed, 15 Jul 2026 11:18:59 +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=1784114341; cv=none; b=UT9SohwkVagHPJYXeK0aBwxdnalLd2HzHmbk1h7xlkeukFh0hRSLorGs6iIEE0LtO8NEgJgp1Iy2NXB2k+yr/8Fp3IpAC8LGB7ZziWWCQWfV+cgMBpec4EgmxBmTE+76ikFa+oNmpYz3vJOxvmTTIxHcdInga3UaXTtmZXrlwCA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784114341; c=relaxed/simple; bh=M7nWun3z+db3sBAe7iYaXrTLAK9O6JS/QNOYDD0lRw0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=c86HAOK7YGq26LbmtjCOgSkoNAhd1v0f7a001SZwSb0REIsyAufo4cGIZits4NuCrbrigc46y7gcG8zArDNIMpuSB1fxwfEQ+dUm4wfQSIM34HeWOKcwkR02VIDvIJSMXWGgIcK1fmrqqyB13Htd60Ilz/2iN7qA7031ZUiRDfI= 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=uKHK81Vu; 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="uKHK81Vu" 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 8284D2F; Wed, 15 Jul 2026 04:18:54 -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 B4BFC3F915; Wed, 15 Jul 2026 04:18:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1784114338; bh=M7nWun3z+db3sBAe7iYaXrTLAK9O6JS/QNOYDD0lRw0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uKHK81Vughycr2Fec3IOhaO6pqa5BpmtEOeHailq6wIswGpOLQ4C+aaS9XlvZ0xbi nEHkhqvkygf3VZQBfxA4v7HvSZi4GAEOBqlquC8V4znMgkmNArWBoC2zW38CKyjnwH /FUcGpSp76LzA+o93S4NTnGtMkhs3dE+dUq+rIrU= From: Dev Jain To: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org Cc: Dev Jain , liam@infradead.org, 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, 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 1/3] mm/memory: move pte_install_uffd_wp_if_needed() into memory.c Date: Wed, 15 Jul 2026 11:18:34 +0000 Message-ID: <20260715111839.1667914-2-dev.jain@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260715111839.1667914-1-dev.jain@arm.com> References: <20260715111839.1667914-1-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. 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 --- include/linux/mm.h | 2 ++ include/linux/mm_inline.h | 53 ---------------------------------- mm/memory.c | 60 +++++++++++++++++++++++++++++++++++++++ 3 files changed, 62 insertions(+), 53 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 550fb92957d18..a71341c44655e 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -5406,4 +5406,6 @@ void map_anon_folio_pte_nopf(struct folio *folio, pte= _t *pte, struct vm_area_struct *vma, unsigned long addr, bool uffd_wp); =20 +bool pte_install_uffd_wp_if_needed(struct vm_area_struct *vma, + unsigned long addr, pte_t *ptep, pte_t pte); #endif /* _LINUX_MM_H */ 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/memory.c b/mm/memory.c index d5e87624f6920..98b3ace15cef2 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 write-protected normal pte */ + if (unlikely(pte_present(pte) && pte_uffd(pte))) + arm_uffd_pte =3D true; + + /* + * A uffd-wp write-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 17:33:42 2026 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 6DA173644C5 for ; Wed, 15 Jul 2026 11:19:06 +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=1784114348; cv=none; b=dMccyjU768rK1Hy4sln4mB5EXNZ89J/mYn3s3Fa2cOlCQJmvt15jpupkl2AYoHsgxok/GqV7fp12/MNpx6j47jVvhfOqlE0Ald794IzJJGqnZgyaCGmKBeJJfNgGeVyVFu13eRuhDvapD22dLow3AiNduI60xoE9QbF9IX5w0YU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784114348; c=relaxed/simple; bh=FASJfRiTYqPOAEgL4yWBpkca2p01JpG0G1APx8Od+GI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=tXT0OldbaD6NxF88nOXvzyVCIwcjFEk5WkreDhz3fHU90ZrSKJUrbuDf892D9ddXlh5jsW1cKMYbRo09Adb2b9HJZj0yUxW16/0wgU56+4gs4fCaZifQT6+YW+JxGOice+LmS6dxPPP/BpcY7nAhAlyHMN40yca7s3aBpHr8Bmc= 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=TSyiesxW; 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="TSyiesxW" 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 23C991477; Wed, 15 Jul 2026 04:19:01 -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 5602D3F915; Wed, 15 Jul 2026 04:18:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1784114345; bh=FASJfRiTYqPOAEgL4yWBpkca2p01JpG0G1APx8Od+GI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TSyiesxWF+4lR5EXk4mJ8aedDhJdaZr5m6Ev+e3nDI2m73M0OUfsk7FB+lhm5eOtu +ssIUymltMwxLBuDjFjNmuScj5fBtfHkZi6H0MeKLaBRTZhXaitWiZgodxES19d3BN eqw+Zq1ohFviuknmQalmTbW1tD/w//s76UbIdHfk= From: Dev Jain To: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org Cc: Dev Jain , liam@infradead.org, 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, 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 2/3] mm/memory: batch set uffd-wp markers during zapping Date: Wed, 15 Jul 2026 11:18:35 +0000 Message-ID: <20260715111839.1667914-3-dev.jain@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260715111839.1667914-1-dev.jain@arm.com> References: <20260715111839.1667914-1-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 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, 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 being marked with uffd-wp or all being not marked (same is the case with the pte_swp_uffd_wp_any check) 3) uffd_supports_wp_marker() is independent of the function parameters 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. Rename the function to cond_install_uffd_wp_ptes. Signed-off-by: Dev Jain --- To handle nonpresent->nonpresent transition in the ptes, we can have a set_nonpresent_ptes() (in my unmap series) : if !softleaf_has_pfn(), use set the same pte value to all ptep's in the patch. if softleaf_has_pfn(), then add a softleaf_next_pfn() to construct the next softleaf, and pte_next_softleaf() to call softleaf_next_pfn() and preserve the wp bit, s-d bit, etc from the previous pte. include/linux/mm.h | 6 +++-- mm/memory.c | 64 +++++++++++++++++----------------------------- mm/rmap.c | 2 +- 3 files changed, 29 insertions(+), 43 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index a71341c44655e..94e0a92bc70b1 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -5406,6 +5406,8 @@ void map_anon_folio_pte_nopf(struct folio *folio, pte= _t *pte, struct vm_area_struct *vma, unsigned long addr, bool uffd_wp); =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 a= ddr, + pte_t *ptep, pte_t pte, + unsigned long nr_ptes); + #endif /* _LINUX_MM_H */ diff --git a/mm/memory.c b/mm/memory.c index 98b3ace15cef2..5d2b567b383d4 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 - * 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. + * 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 PT= Es + * are already cleared so we will never accidentally replace something + * valuable. Meanwhile none PTEs also mean we are not demoting the PTEs so= a + * TLB flush is not needed. E.g., when 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 t= able - * lock. + * Must be called with the page table lock held so that no thread will see + * the 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 =3D false; =20 @@ -1726,13 +1728,14 @@ 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 (unsigned long i =3D 0; i < nr_ptes; ++i, ++ptep, addr +=3D PAGE_SIZE) set_pte_at(vma->vm_mm, addr, ptep, make_pte_marker(PTE_MARKER_UFFD_WP)); - return true; - } =20 - return false; + return true; } =20 /* @@ -1746,29 +1749,10 @@ 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 ad820fe86f7d8..2f938d0ac6953 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -2345,7 +2345,7 @@ 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 17:33:42 2026 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id ED1D73164C5 for ; Wed, 15 Jul 2026 11:19:12 +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=1784114354; cv=none; b=oI+RXk9x3OSyt6mDTCOTM2vLQG1ei1mcc3G3vl9mxkekQ5rJdCTB8oZSfe4/zQY/vIq2n5lqRzybtbSYJzQ2DjyDJu3adtuqeBcV1Sl4F9M+6t/6oWwfStzM96BXKQMhtWqBr5g3lO2CKkihl8lQ+z38HW3fP5i8VE2Q0hs9R74= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784114354; c=relaxed/simple; bh=+o9DpSGseXucY8pTcFbS+W9IBHMvf3AT4jdAayQBJ8o=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=SwYrWrposq4Um68YDhax3i3bVlOZ1/586hiSyIY3/ohUdY//EUXLBapT8MCm8sxdAIadD9QJ/NJ1gtH7/LxR6fuSsoHyRJb6fVFp+LWbxc5vR04bwA2KVY5k/+3yxy4xLzsJi/gLSCLztxNZTW2EpZJY81lm2fQZNILIeSMTpDA= ARC-Authentication-Results: i=1; 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t=1784114352; bh=+o9DpSGseXucY8pTcFbS+W9IBHMvf3AT4jdAayQBJ8o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cMFHUiaeqiLmMlN8BYlKnh6OjgLR9tKyb3ltisY+8hUHTgVbih7101lm/gflcV05s aK+QLl9e+84ArIvxO/iHsUkLoj8mfp9CmE7xTuFSSUpzMRuCkkprSSvhYSYcCuxIMl yoBAn5gFAkv7F+upQWY0lmCysJeHP6wuXfi+kueM= From: Dev Jain To: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org Cc: Dev Jain , liam@infradead.org, 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, 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 3/3] mm/rmap: batch unmap file folios belonging to uffd-wp VMAs Date: Wed, 15 Jul 2026 11:18:36 +0000 Message-ID: <20260715111839.1667914-4-dev.jain@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260715111839.1667914-1-dev.jain@arm.com> References: <20260715111839.1667914-1-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 fo= lios") extended batched unmapping for file folios. That also required making install_uffd_wp_pte_if_needed() support batching, but that was left out for the time being, and correctness was maintained by stopping batching in case the VMA the folio belongs to is marked uffd-wp. Now that we have a batched version called cond_install_uffd_wp_ptes, simply call that. folio_unmap_pte_batch() ensures that the original state of the ptes is either all uffd or all non-uffd, so we maintain correctness. If uffd-wp bit is there, we have the following transitions of ptes after unmapping, for a file folio: present -> uffd-wp marker We must ensure that these ptes are not reprocessed by the while loop - if the batch length is less than the number of pages in the folio, then we must skip over this batch. The page_vma_mapped_walk API ensures this - check_pte() will return true only if any of [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 we keep skipping until we hit a present entry, which is where we want to batch from next. Note that for the uffd-rwp case, we already do not make a uffd marker in cond_install_uffd_wp_ptes. Signed-off-by: Dev Jain Acked-by: David Hildenbrand (Arm) --- Dropped David's ACK due to the uffd-rwp changes. mm/rmap.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/mm/rmap.c b/mm/rmap.c index 2f938d0ac6953..ac88673600fa0 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1965,9 +1965,6 @@ 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 @@ -2345,7 +2342,8 @@ 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