From nobody Wed Sep 30 20:13:06 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A839F3E9C1E; Thu, 6 Aug 2026 20:22:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786047753; cv=none; b=TtoHr0EunpOr4G6Vwrb1TouJdIbx4stnrpvCNgRGSzdbxd0fyPwa+JXJKPFvIRnO0FuCaY4gmRJn4fZ0r71lfxS9ll0dpma12YN/JgVvDmhkt5AiGwYXRrTmwOV5fRn6T5gjsqG0XqDVEIVm/xvVNZkVVkGcHhNB4UK703gP11Q= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786047753; c=relaxed/simple; bh=k4nsxhVksl7Id9wH8PF9j9dwGi3ny6iiiLSmQsKoHuc=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=r5V84RAieX1mGEo33bLYBJyuWVzchtuBQ59Zzxw3gqqY7dxMHywCAQRunau2e+tRHmaLJPvojvLTyVu1gaES+5+lUIe5dRfrFCKdGX4Orpmg+354g9o6ho53/DBxRf8AKcZYoY1/VgT0oQQAp4Yjes+UBluKz3cV/Rt5Tn2eCHg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=TMzl/XFi; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="TMzl/XFi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2B1CE1F00A3A; Thu, 6 Aug 2026 20:22:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786047751; bh=DbE5DHkTNtU6STxh6PeRdePiOC2bhJBQkXlvls/SNVM=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=TMzl/XFi21X4tsBCnRCR9TNBNox7KbNEllmPiQhMneHl56UnH3IY2WyFV5kgsGON1 gCCsHf8Qbq7ywDSVCxRdWE1a2j+d0br2parJnmtlU6vwRzmiWL9qZ/a6zIhFZAJ1+y 964a/C63WGUIYlX4GGopipjuIfvtdgWCsQwsoy+NUtBafM4jlcdlX3CkSYFHjIVswx SuDCMVlEEhgHgrBoFCR4FsFp5s87C4eThJTtUMjThiuA4cJwDtQpzjx8r96pMGkHs+ XGVPGbJ8R8g0o89ySggGdO9FRJu5nHne+zS/cBubMzrWbvB4RmF7JCT7YZ4vwIMKBh JqxZRwE2/Gnbg== From: "Lorenzo Stoakes (ARM)" Date: Thu, 06 Aug 2026 21:21:26 +0100 Subject: [PATCH v4 01/20] mm/vma: introduce VMA anon page offset field and add helpers Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260806-b4-scalable-cow-virt-pgoff-v4-1-ab318a350404@kernel.org> References: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> In-Reply-To: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> To: Andrew Morton , David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Miaohe Lin , Naoya Horiguchi , Rik van Riel , Harry Yoo , Lance Yang , Kees Cook , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Usama Arif , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Peter Xu , Xu Xin , Chengming Zhou , Arnd Bergmann , Greg Kroah-Hartman , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Sven Schnelle , Alex Deucher , =?utf-8?q?Christian_K=C3=B6nig?= , David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Boris Brezillon , Steven Price , Liviu Dudau , Huang Rui , Matthew Auld , =?utf-8?q?Thomas_Hellstr=C3=B6m?= , Rodrigo Vivi , Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Jason Gunthorpe , John Hubbard , Muchun Song , Oscar Salvador , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Youngjun Park Cc: "Lorenzo Stoakes (ARM)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, intel-xe@lists.freedesktop.org, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=8006; i=ljs@kernel.org; h=from:subject:message-id; bh=k4nsxhVksl7Id9wH8PF9j9dwGi3ny6iiiLSmQsKoHuc=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLJK3pxfUcnML3kp/giHiryrULlr4rfA9lf1b49o1HfOv Syr0pDeUcrCIMbFICumyPL8i/j+IJGweZ0X/N1g5rAygQxh4OIUgInsPsLwP7XYNkPmQXnFwwhT zyIHQ7EJ9tMuzfx49SbnkRDTPIdbSxj+59puyvhklba2LXxiss6JVo93jOvUrFOWbFkvlTqlmfU 3HwA= X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 Establish fields in vm_area_struct to store the anonymous page offset of VMAs. Initially, the anonymous page offset of a VMA is vma->vm_start >> PAGE_SHIFT. When a VMA is remapped to new_address its anonymous page offset is either updated to new_address >> PAGE_SHIFT if unfaulted or, if faulted, remains equal to the anonymous page offset it had when first faulted. Currently, anonymous folios belonging to CoW'd MAP_PRIVATE-mapped file-backed VMAs are tracked by their file offsets. By adding anonymous offset as a property of VMAs, we can now track them by their anonymous page offset instead. By tracking this, we provide the means by which to eliminate this inconsistency, and more importantly lay the foundations for future work for the scalable CoW anonymous rmap rework. This patch simply adds the fields and some simple helpers. Subsequent patches will update mm code to make use of these fields correctly. The fields chosen are packed in the VMA such that, for 64-bit kernel builds, no additional space is taken up. The first field is present on cacheline 0 containing key VMA fields, and the second on cacheline 3, which contains file-backed reverse mapping fields. Given the relative time spent accessing reverse mapping fields as well as updating them, there shouldn't be any performance impact here from false sharing. Update the VMA userland tests to account for this change. No callsites are updated yet, so no functional change intended. Acked-by: David Hildenbrand (Arm) Reviewed-by: Gregory Price (Meta) Reviewed-by: Xu Xin Signed-off-by: Lorenzo Stoakes (ARM) --- include/linux/mm.h | 59 +++++++++++++++++++++++++++++++++++++= ++++ include/linux/mm_types.h | 12 +++++++++ mm/vma.h | 14 ++++++++++ mm/vma_init.c | 1 + tools/testing/vma/include/dup.h | 26 ++++++++++++++++++ 5 files changed, 112 insertions(+) diff --git a/include/linux/mm.h b/include/linux/mm.h index 87feaa5a2b78..df78847f5f07 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -4393,6 +4393,65 @@ static inline pgoff_t vma_last_pgoff(const struct vm= _area_struct *vma) return vma_end_pgoff(vma) - 1; } =20 +/** + * vma_start_anon_pgoff() - Get the anonymous page offset of the start of = @vma + * @vma: The VMA whose anonymous page offset is required. + * + * If unfaulted, then this is vma->vm_start >> PAGE_SHIFT, if faulted then= the + * anonymous page offset at the time of first fault. + * + * If the VMA is anonymous, this returns the same value as vma_start_pgoff= (). + * + * This value is used for tracking MAP_PRIVATE file-backed mappings by the= ir + * anonymous page offset. + * + * Returns: The anonymous page offset of the start of @vma. + */ +static inline pgoff_t vma_start_anon_pgoff(const struct vm_area_struct *vm= a) +{ + pgoff_t pgoff =3D 0; + +#ifdef CONFIG_64BIT + pgoff +=3D vma->__vm_anon_pgoff_hi; + pgoff <<=3D 32; +#endif + pgoff +=3D vma->__vm_anon_pgoff_lo; + return pgoff; +} + +/** + * vma_end_anon_pgoff() - Get the anonymous page offset of the exclusive e= nd of + * @vma. + * @vma: The VMA whose end anonymous page offset is required. + * + * This returns the anonymous exclusive end page offset of @vma, which is = useful + * for expressing page offset ranges. + * + * See the description of vma_start_anon_pgoff() for a description of VMA + * anonymous page offsets. + * + * Returns: The exclusive end anonymous page offset of @vma. + */ +static inline pgoff_t vma_end_anon_pgoff(const struct vm_area_struct *vma) +{ + return vma_start_anon_pgoff(vma) + vma_pages(vma); +} + +/** + * vma_last_anon_pgoff() - Get the anonymous page offset of the last page = in + * @vma. + * @vma: The VMA whose last anonymous page offset is required. + * + * See the description of vma_start_anon_pgoff() for a description of VMA + * anonymous page offsets. + * + * Returns: The last anonymous page offset of @vma. + */ +static inline pgoff_t vma_last_anon_pgoff(const struct vm_area_struct *vma) +{ + return vma_end_anon_pgoff(vma) - 1; +} + static inline unsigned long vma_desc_size(const struct vm_area_desc *desc) { return desc->end - desc->start; diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 939b5ea8c9e0..ebf0d912be7d 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -967,6 +967,11 @@ struct vm_area_struct { */ unsigned int vm_lock_seq; #endif + /* + * Low 32-bits of anonymous page offset. + * See vma_start_anon_pgoff() comment for details. + */ + unsigned int __vm_anon_pgoff_lo; /* * A file's MAP_PRIVATE vma can be in both i_mmap tree and anon_vma * list, after a COW of one of the file pages. A MAP_SHARED vma @@ -1041,6 +1046,13 @@ struct vm_area_struct { #ifdef CONFIG_DEBUG_LOCK_ALLOC struct lockdep_map vmlock_dep_map; #endif +#endif +#ifdef CONFIG_64BIT + /* + * High 32-bits of anonymous page offset. + * See vma_start_anon_pgoff() comment for details. + */ + unsigned int __vm_anon_pgoff_hi; #endif /* * For areas with an address space and backing store, diff --git a/mm/vma.h b/mm/vma.h index 0bc7d521e976..54ed7c744e3b 100644 --- a/mm/vma.h +++ b/mm/vma.h @@ -283,6 +283,20 @@ static inline void vma_set_pgoff(struct vm_area_struct= *vma, pgoff_t pgoff) vma->vm_pgoff =3D pgoff; } =20 +static inline void __vma_set_anon_pgoff(struct vm_area_struct *vma, pgoff_= t pgoff) +{ +#ifdef CONFIG_64BIT + vma->__vm_anon_pgoff_hi =3D pgoff >> 32; +#endif + vma->__vm_anon_pgoff_lo =3D pgoff & GENMASK(31, 0); +} + +static inline void vma_set_anon_pgoff(struct vm_area_struct *vma, pgoff_t = pgoff) +{ + vma_assert_can_modify(vma); + __vma_set_anon_pgoff(vma, pgoff); +} + static inline void vma_add_pgoff(struct vm_area_struct *vma, pgoff_t delta) { vma_assert_can_modify(vma); diff --git a/mm/vma_init.c b/mm/vma_init.c index 715feee283f0..baa7e82f47e3 100644 --- a/mm/vma_init.c +++ b/mm/vma_init.c @@ -51,6 +51,7 @@ static void vm_area_init_from(const struct vm_area_struct= *src, dest->vm_end =3D src->vm_end; dest->anon_vma =3D src->anon_vma; dest->vm_pgoff =3D vma_start_pgoff(src); + __vma_set_anon_pgoff(dest, vma_start_anon_pgoff(src)); dest->vm_file =3D src->vm_file; dest->vm_private_data =3D src->vm_private_data; vm_flags_init(dest, src->vm_flags); diff --git a/tools/testing/vma/include/dup.h b/tools/testing/vma/include/du= p.h index c52b23773cd2..26d9210b1e8b 100644 --- a/tools/testing/vma/include/dup.h +++ b/tools/testing/vma/include/dup.h @@ -577,6 +577,7 @@ struct vm_area_struct { */ unsigned int vm_lock_seq; #endif + unsigned int __vm_anon_pgoff_lo; =20 /* * A file's MAP_PRIVATE vma can be in both i_mmap tree and anon_vma @@ -612,6 +613,9 @@ struct vm_area_struct { #ifdef CONFIG_PER_VMA_LOCK /* Unstable RCU readers are allowed to read this. */ refcount_t vm_refcnt; +#endif +#ifdef CONFIG_64BIT + unsigned int __vm_anon_pgoff_hi; #endif /* * For areas with an address space and backing store, @@ -1320,6 +1324,28 @@ static inline pgoff_t vma_end_pgoff(const struct vm_= area_struct *vma) return vma_start_pgoff(vma) + vma_pages(vma); } =20 +static inline pgoff_t vma_start_anon_pgoff(const struct vm_area_struct *vm= a) +{ + pgoff_t pgoff =3D 0; + +#ifdef CONFIG_64BIT + pgoff +=3D vma->__vm_anon_pgoff_hi; + pgoff <<=3D 32; +#endif + pgoff +=3D vma->__vm_anon_pgoff_lo; + return pgoff; +} + +static inline pgoff_t vma_end_anon_pgoff(const struct vm_area_struct *vma) +{ + return vma_start_anon_pgoff(vma) + vma_pages(vma); +} + +static inline pgoff_t vma_last_anon_pgoff(const struct vm_area_struct *vma) +{ + return vma_end_anon_pgoff(vma) - 1; +} + static inline int vfs_mmap_prepare(struct file *file, struct vm_area_desc = *desc) { return file->f_op->mmap_prepare(desc); --=20 2.55.0 From nobody Wed Sep 30 20:13:06 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7D2F31EB19B; 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dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="XXE4sYAY" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D2DAF1F000E9; Thu, 6 Aug 2026 20:22:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786047772; bh=jAWi93tteqsMNI4R2OumTdu2t8reun/HOO0+iBU7Y6U=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=XXE4sYAYPvr+PEFQ0FdIwQunnJejWY9UR4PHl+cRyosAU/tYW/DtCgwPGPkEltz3t h8w3sU3aH3KIqT8ImT3sBnVh6eEWw10m8rfiupgBAwsjZHWzT2yyJjTL0XSgPUXvSd ML+DnnVIVc4Y3/peVZFDL+8/sDH+HNTEjXtRuINojPQKNJ4pnsmfw4lgTBzCaTTXzy hN/x+Z4yhMCpoKtaJgxsgwUdYRu1dt5fsiPFcR/+Yt1QNtjVwyAFYHCWuq98paPPiE XOanTifGQsUU5kZICN9fJ0OXjBH9tcx/7bT9mtztE7dGb5Kvw/RPpeOytQ/wWFm9JZ BH02ZZG0aRNxA== From: "Lorenzo Stoakes (ARM)" Date: Thu, 06 Aug 2026 21:21:27 +0100 Subject: [PATCH v4 02/20] mm: provide vma_[flags_]is_cow_mapping() and remove is_cow_mapping() Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260806-b4-scalable-cow-virt-pgoff-v4-2-ab318a350404@kernel.org> References: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> In-Reply-To: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> To: Andrew Morton , David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Miaohe Lin , Naoya Horiguchi , Rik van Riel , Harry Yoo , Lance Yang , Kees Cook , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Usama Arif , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Peter Xu , Xu Xin , Chengming Zhou , Arnd Bergmann , Greg Kroah-Hartman , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Sven Schnelle , Alex Deucher , =?utf-8?q?Christian_K=C3=B6nig?= , David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Boris Brezillon , Steven Price , Liviu Dudau , Huang Rui , Matthew Auld , =?utf-8?q?Thomas_Hellstr=C3=B6m?= , Rodrigo Vivi , Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Jason Gunthorpe , John Hubbard , Muchun Song , Oscar Salvador , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Youngjun Park Cc: "Lorenzo Stoakes (ARM)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, intel-xe@lists.freedesktop.org, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=16544; i=ljs@kernel.org; h=from:subject:message-id; bh=8xVRumSCjVSb6eGVXrjrRj8juxOTPyHD6yRzx20H9us=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLJK3pxX8qyUnv9X7NdJV9HCNy2zj8tsaL23YuOtSfua6 59UZMz17ShlYRDjYpAVU2R5/kV8f5BI2LzOC/5uMHNYmUCGMHBxCsBE1DMZ/gqF1K/MPrBa+vT0 dRXLtmqxhxedKZ40eY5wYWBx0LEbebGMDMeuzwg5oti1R2Rv/DsmgX6JVznMslN8Kkvuzz2eLtY ayw0A X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 All remaining callers of is_cow_mapping() are invoking it in the form of is_cow_mapping(vma->vm_flags) or an indirected version of this. Therefore, provide a helper - vma_is_cow_mapping() to directly test the VMA. Additionally provide a new helper vma_flags_is_cow_mapping() which performs the check using the new vma_flags_t type, and share this logic between vma_is_cow_mapping() and vma_desc_is_cow_mapping(). With these changes, no callers of is_cow_mapping() remain, so remove it. Also update the userland VMA tests to reflect the change. No functional change intended. Signed-off-by: Lorenzo Stoakes (ARM) Acked-by: David Hildenbrand (Arm) --- arch/s390/mm/gmap_helpers.c | 2 +- drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 4 ++-- drivers/gpu/drm/drm_gem_shmem_helper.c | 2 +- drivers/gpu/drm/panthor/panthor_gem.c | 2 +- drivers/gpu/drm/ttm/ttm_bo_vm.c | 2 +- drivers/gpu/drm/xe/xe_device.c | 2 +- fs/proc/task_mmu.c | 2 +- include/linux/mm.h | 15 +++++++++------ kernel/events/uprobes.c | 2 +- mm/gup.c | 2 +- mm/huge_memory.c | 8 ++++---- mm/hugetlb.c | 2 +- mm/internal.h | 2 +- mm/memory.c | 25 ++++++++++++------------- mm/mempolicy.c | 2 +- tools/testing/vma/include/dup.h | 11 +++++++++++ 16 files changed, 49 insertions(+), 36 deletions(-) diff --git a/arch/s390/mm/gmap_helpers.c b/arch/s390/mm/gmap_helpers.c index 4bf7c9012feb..cd5fded159c0 100644 --- a/arch/s390/mm/gmap_helpers.c +++ b/arch/s390/mm/gmap_helpers.c @@ -200,7 +200,7 @@ static int find_zeropage_pte_entry(pte_t *pte, unsigned= long addr, * currently only works in COW mappings, which is also where * mm_forbids_zeropage() is checked. */ - if (!is_cow_mapping(walk->vma->vm_flags)) + if (!vma_is_cow_mapping(walk->vma)) return -EFAULT; =20 *found_addr =3D addr; diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/= amdgpu/amdgpu_gem.c index 6a0699746fbc..0c7309080a7a 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c @@ -377,9 +377,9 @@ static int amdgpu_gem_object_mmap(struct drm_gem_object= *obj, struct vm_area_str /* Workaround for Thunk bug creating PROT_NONE,MAP_PRIVATE mappings * for debugger access to invisible VRAM. Should have used MAP_SHARED * instead. Clearing VM_MAYWRITE prevents the mapping from ever - * becoming writable and makes is_cow_mapping(vm_flags) false. + * becoming writable and makes vma_is_cow_mapping(vma) false. */ - if (is_cow_mapping(vma->vm_flags) && + if (vma_is_cow_mapping(vma) && !(vma->vm_flags & VM_ACCESS_FLAGS)) vm_flags_clear(vma, VM_MAYWRITE); =20 diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_g= em_shmem_helper.c index 06d019d51d3e..177d0e0b9334 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -753,7 +753,7 @@ int drm_gem_shmem_mmap(struct drm_gem_shmem_object *shm= em, struct vm_area_struct return ret; } =20 - if (is_cow_mapping(vma->vm_flags)) + if (vma_is_cow_mapping(vma)) return -EINVAL; =20 dma_resv_lock(shmem->base.resv, NULL); diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/drm/pantho= r/panthor_gem.c index 770556353968..d2eec46f7abe 100644 --- a/drivers/gpu/drm/panthor/panthor_gem.c +++ b/drivers/gpu/drm/panthor/panthor_gem.c @@ -761,7 +761,7 @@ static int panthor_gem_mmap(struct drm_gem_object *obj,= struct vm_area_struct *v return ret; } =20 - if (is_cow_mapping(vma->vm_flags)) + if (vma_is_cow_mapping(vma)) return -EINVAL; =20 if (!refcount_inc_not_zero(&bo->cmap.mmap_count)) { diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_v= m.c index 88babf435ac2..872bf444b1f0 100644 --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c @@ -489,7 +489,7 @@ static const struct vm_operations_struct ttm_bo_vm_ops = =3D { int ttm_bo_mmap_obj(struct vm_area_struct *vma, struct ttm_buffer_object *= bo) { /* Enforce no COW since would have really strange behavior with it. */ - if (is_cow_mapping(vma->vm_flags)) + if (vma_is_cow_mapping(vma)) return -EINVAL; =20 drm_gem_object_get(&bo->base); diff --git a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c index 838797cc65d7..ab16937ebbe0 100644 --- a/drivers/gpu/drm/xe/xe_device.c +++ b/drivers/gpu/drm/xe/xe_device.c @@ -330,7 +330,7 @@ static int xe_pci_barrier_mmap(struct file *filp, if (vma->vm_end - vma->vm_start > SZ_4K) return -EINVAL; =20 - if (is_cow_mapping(vma->vm_flags)) + if (vma_is_cow_mapping(vma)) return -EINVAL; =20 if (vma->vm_flags & (VM_READ | VM_EXEC)) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 817e3e0f9194..5c54aebe2118 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1693,7 +1693,7 @@ static inline bool pte_is_pinned(struct vm_area_struc= t *vma, unsigned long addr, =20 if (!pte_write(pte)) return false; - if (!is_cow_mapping(vma->vm_flags)) + if (!vma_is_cow_mapping(vma)) return false; if (likely(!mm_flags_test(MMF_HAS_PINNED, vma->vm_mm))) return false; diff --git a/include/linux/mm.h b/include/linux/mm.h index df78847f5f07..a3368c542947 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2271,17 +2271,20 @@ void unpin_user_pages(struct page **pages, unsigned= long npages); void unpin_user_folio(struct folio *folio, unsigned long npages); void unpin_folios(struct folio **folios, unsigned long nfolios); =20 -static inline bool is_cow_mapping(vm_flags_t flags) +static inline bool vma_flags_is_cow_mapping(const vma_flags_t *flags) { - return (flags & (VM_SHARED | VM_MAYWRITE)) =3D=3D VM_MAYWRITE; + return vma_flags_test(flags, VMA_MAYWRITE_BIT) && + !vma_flags_test(flags, VMA_SHARED_BIT); } =20 -static inline bool vma_desc_is_cow_mapping(struct vm_area_desc *desc) +static inline bool vma_is_cow_mapping(const struct vm_area_struct *vma) { - const vma_flags_t *flags =3D &desc->vma_flags; + return vma_flags_is_cow_mapping(&vma->flags); +} =20 - return vma_flags_test(flags, VMA_MAYWRITE_BIT) && - !vma_flags_test(flags, VMA_SHARED_BIT); +static inline bool vma_desc_is_cow_mapping(struct vm_area_desc *desc) +{ + return vma_flags_is_cow_mapping(&desc->vma_flags); } =20 #ifndef CONFIG_MMU diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index ae2f3b9f8d50..eb0d11092fb3 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -513,7 +513,7 @@ int uprobe_write(struct arch_uprobe *auprobe, struct vm= _area_struct *vma, =20 uprobe =3D container_of(auprobe, struct uprobe, arch); =20 - if (WARN_ON_ONCE(!is_cow_mapping(vma->vm_flags))) + if (WARN_ON_ONCE(!vma_is_cow_mapping(vma))) return -EINVAL; =20 /* diff --git a/mm/gup.c b/mm/gup.c index 1d32e9a3dc79..b534ef58c46a 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -1236,7 +1236,7 @@ static int check_vma_flags(struct vm_area_struct *vma= , unsigned long gup_flags) * Anon pages in shared mappings are surprising: now * just reject it. */ - if (!is_cow_mapping(vm_flags)) + if (!vma_is_cow_mapping(vma)) return -EFAULT; } } else if (!(vm_flags & VM_READ)) { diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 9b1f3b24f7e0..6b0cabd45b2d 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1638,7 +1638,7 @@ vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, u= nsigned long pfn, BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) =3D=3D (VM_PFNMAP|VM_MIXEDMAP)); - BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); + BUG_ON((vma->vm_flags & VM_PFNMAP) && vma_is_cow_mapping(vma)); =20 pfnmap_setup_cachemode_pfn(pfn, &pgprot); =20 @@ -1746,7 +1746,7 @@ vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, u= nsigned long pfn, BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) =3D=3D (VM_PFNMAP|VM_MIXEDMAP)); - BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); + BUG_ON((vma->vm_flags & VM_PFNMAP) && vma_is_cow_mapping(vma)); =20 pfnmap_setup_cachemode_pfn(pfn, &pgprot); =20 @@ -1888,7 +1888,7 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm= _struct *src_mm, * applied special bit, or we made the PRIVATE mapping be * able to wrongly write to the backend MMIO. */ - VM_WARN_ON_ONCE(is_cow_mapping(src_vma->vm_flags) && pmd_write(pmd)); + VM_WARN_ON_ONCE(vma_is_cow_mapping(src_vma) && pmd_write(pmd)); goto set_pmd; } =20 @@ -2009,7 +2009,7 @@ int copy_huge_pud(struct mm_struct *dst_mm, struct mm= _struct *src_mm, * TODO: once we support anonymous pages, use * folio_try_dup_anon_rmap_*() and split if duplicating fails. */ - if (is_cow_mapping(vma->vm_flags) && pud_write(pud)) { + if (vma_is_cow_mapping(vma) && pud_write(pud)) { pudp_set_wrprotect(src_mm, addr, src_pud); pud =3D pud_wrprotect(pud); } diff --git a/mm/hugetlb.c b/mm/hugetlb.c index d86a27c8819c..560e85ca1d1c 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -4905,7 +4905,7 @@ int copy_hugetlb_page_range(struct mm_struct *dst, st= ruct mm_struct *src, pte_t *src_pte, *dst_pte, entry; struct folio *pte_folio; unsigned long addr; - bool cow =3D is_cow_mapping(src_vma->vm_flags); + bool cow =3D vma_is_cow_mapping(src_vma); struct hstate *h =3D hstate_vma(src_vma); unsigned long sz =3D huge_page_size(h); unsigned long npages =3D pages_per_huge_page(h); diff --git a/mm/internal.h b/mm/internal.h index f26423de4ca2..a75a1344e9ba 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -1341,7 +1341,7 @@ static inline bool gup_must_unshare(struct vm_area_st= ruct *vma, * ... because we only care about writable private ("COW") * mappings where we have to break COW early. */ - return is_cow_mapping(vma->vm_flags); + return vma_is_cow_mapping(vma); } =20 /* Paired with a memory barrier in folio_try_share_anon_rmap_*(). */ diff --git a/mm/memory.c b/mm/memory.c index d5e87624f692..e1349e18f046 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -780,7 +780,7 @@ static inline struct page *__vm_normal_page(struct vm_a= rea_struct *vma, /* Only CoW'ed anon folios are "normal". */ if (pfn =3D=3D index) return NULL; - if (!is_cow_mapping(vma->vm_flags)) + if (!vma_is_cow_mapping(vma)) return NULL; } } @@ -1002,7 +1002,6 @@ copy_nonpresent_pte(struct mm_struct *dst_mm, struct = mm_struct *src_mm, pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, unsigned long addr, int *rss) { - vm_flags_t vm_flags =3D dst_vma->vm_flags; pte_t orig_pte =3D ptep_get(src_pte); softleaf_t entry =3D softleaf_from_pte(orig_pte); pte_t pte =3D orig_pte; @@ -1026,7 +1025,7 @@ copy_nonpresent_pte(struct mm_struct *dst_mm, struct = mm_struct *src_mm, rss[mm_counter(folio)]++; =20 if (!softleaf_is_migration_read(entry) && - is_cow_mapping(vm_flags)) { + vma_is_cow_mapping(dst_vma)) { /* * COW mappings require pages in both parent and child * to be set to read. A previously exclusive entry is @@ -1067,7 +1066,7 @@ copy_nonpresent_pte(struct mm_struct *dst_mm, struct = mm_struct *src_mm, * save and restore device driver state). */ if (softleaf_is_device_private_write(entry) && - is_cow_mapping(vm_flags)) { + vma_is_cow_mapping(dst_vma)) { entry =3D make_readable_device_private_entry( swp_offset(entry)); pte =3D swp_entry_to_pte(entry); @@ -1082,7 +1081,7 @@ copy_nonpresent_pte(struct mm_struct *dst_mm, struct = mm_struct *src_mm, * exclusive entries currently only support private writable * (ie. COW) mappings. */ - VM_BUG_ON(!is_cow_mapping(src_vma->vm_flags)); + VM_BUG_ON(!vma_is_cow_mapping(src_vma)); if (try_restore_exclusive_pte(src_vma, addr, src_pte, orig_pte)) return -EBUSY; return -ENOENT; @@ -1181,7 +1180,7 @@ static __always_inline void __copy_present_ptes(struc= t vm_area_struct *dst_vma, } =20 /* If it's a COW mapping, write protect it both processes. */ - if (is_cow_mapping(src_vma->vm_flags) && writable) { + if (vma_is_cow_mapping(src_vma) && writable) { wrprotect_ptes(src_mm, addr, src_pte, nr); pte =3D pte_wrprotect(pte); } @@ -1602,9 +1601,9 @@ copy_page_range(struct vm_area_struct *dst_vma, struc= t vm_area_struct *src_vma) * We need to invalidate the secondary MMU mappings only when * there could be a permission downgrade on the ptes of the * parent mm. And a permission downgrade will only happen if - * is_cow_mapping() returns true. + * vma_is_cow_mapping() returns true. */ - is_cow =3D is_cow_mapping(src_vma->vm_flags); + is_cow =3D vma_is_cow_mapping(src_vma); =20 if (is_cow) { mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE, @@ -2388,7 +2387,7 @@ static bool vm_mixed_zeropage_allowed(struct vm_area_= struct *vma) if (mm_forbids_zeropage(vma->vm_mm)) return false; /* zeropages in COW mappings are common and unproblematic. */ - if (is_cow_mapping(vma->vm_flags)) + if (vma_is_cow_mapping(vma)) return true; /* Mappings that do not allow for writable PTEs are unproblematic. */ if (!(vma->vm_flags & (VM_WRITE | VM_MAYWRITE))) @@ -2839,7 +2838,7 @@ vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct = *vma, unsigned long addr, BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) =3D=3D (VM_PFNMAP|VM_MIXEDMAP)); - BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); + BUG_ON((vma->vm_flags & VM_PFNMAP) && vma_is_cow_mapping(vma)); BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn)); =20 if (addr < vma->vm_start || addr >=3D vma->vm_end) @@ -3251,7 +3250,7 @@ static int remap_pfn_range_prepare_vma(struct vm_area= _struct *vma, unsigned long size) { const unsigned long end =3D addr + PAGE_ALIGN(size); - const bool is_cow =3D is_cow_mapping(vma->vm_flags); + const bool is_cow =3D vma_is_cow_mapping(vma); int err; =20 err =3D get_remap_pgoff(is_cow, addr, end, vma->vm_start, vma->vm_end, @@ -6751,7 +6750,7 @@ static vm_fault_t sanitize_fault_flags(struct vm_area= _struct *vma, * FAULT_FLAG_UNSHARE only applies to COW mappings. Let's * just treat it like an ordinary read-fault otherwise. */ - if (!is_cow_mapping(vma->vm_flags)) + if (!vma_is_cow_mapping(vma)) *flags &=3D ~FAULT_FLAG_UNSHARE; } else if (*flags & FAULT_FLAG_WRITE) { /* Write faults on read-only mappings are impossible ... */ @@ -6759,7 +6758,7 @@ static vm_fault_t sanitize_fault_flags(struct vm_area= _struct *vma, return VM_FAULT_SIGSEGV; /* ... and FOLL_FORCE only applies to COW mappings. */ if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE) && - !is_cow_mapping(vma->vm_flags))) + !vma_is_cow_mapping(vma))) return VM_FAULT_SIGSEGV; } #ifdef CONFIG_PER_VMA_LOCK diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 5720f7f54d94..3498a5651d50 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -844,7 +844,7 @@ bool folio_can_map_prot_numa(struct folio *folio, struc= t vm_area_struct *vma, return false; =20 /* Also skip shared copy-on-write folios */ - if (is_cow_mapping(vma->vm_flags) && folio_maybe_mapped_shared(folio)) + if (vma_is_cow_mapping(vma) && folio_maybe_mapped_shared(folio)) return false; =20 /* Folios are pinned and can't be migrated */ diff --git a/tools/testing/vma/include/dup.h b/tools/testing/vma/include/du= p.h index 26d9210b1e8b..40ad83936b28 100644 --- a/tools/testing/vma/include/dup.h +++ b/tools/testing/vma/include/dup.h @@ -1162,6 +1162,17 @@ static inline bool vma_is_shared_maywrite(struct vm_= area_struct *vma) return is_shared_maywrite(&vma->flags); } =20 +static inline bool vma_flags_is_cow_mapping(const vma_flags_t *flags) +{ + return vma_flags_test(flags, VMA_MAYWRITE_BIT) && + !vma_flags_test(flags, VMA_SHARED_BIT); +} + +static inline bool vma_is_cow_mapping(const struct vm_area_struct *vma) +{ + return vma_flags_is_cow_mapping(&vma->flags); +} + static inline struct vm_area_struct *vma_next(struct vma_iterator *vmi) { /* --=20 2.55.0 From nobody Wed Sep 30 20:13:06 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 30A6B3E638E; Thu, 6 Aug 2026 20:23:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786047794; cv=none; b=bNLxG+ZGOz/zr9LPqDqWTBo2Bxh4Tq0GPlOxOlkeP1r9s+YO2sXSyu4kzcwYny5oTwbEsGKkN6YKTffhyaD2akUzlGPMXt55SnrLx7BB+T54yW7/oDLDeYEMFtOssWAxqOSHDSnHFfKNvgWDWU0QE1oTWZV8m08G9kFnyDWQTc8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786047794; c=relaxed/simple; bh=0osG5+4gGXbzb2uNb/Bi6pWK7THgxYoP0n4wymDnQXc=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=FevUHO6XQQkkx2lq/TMS4/jQIKQX0DFxuyDSKfxRvjxcSGREZ7kv4NX7iY/7cimuIkAV7HH8k7CENONdHM8+rdaI8/wxZOD3tMoPWPndOg7NE78ltKkEM14UiGcRMaH7E1cNbOo9Q17FChggWS50Wffb1vmBdbt6awFpIOPEPzU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UcyLgppJ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="UcyLgppJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 867231F00A3A; Thu, 6 Aug 2026 20:22:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786047792; bh=Dt36wRLymxRrIfWXpRPIqrPCDm+fFgCjzU1nKukhsXA=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=UcyLgppJvmOk1gAPp9vuuiCf6zIP9M82q/hU1r2AjcZWCGFyyhKTEXkQXe0owHBtG 4p8OWMOPjQDkFUfSIJfMi0p4E0ewtDiX4gAGD417dxoA+UvVxeRM8yeNzdNB1Xw0jr iN4rV+dqhar2ncC1LBMh5HjTvXvCQAcJAe93Ne4OcL13S4OcUg2YgMzr7H2k0tmchl 57U/RgrQRBqY83ZwoONnzJHfcZ1meHUQGlVWRNidXgnyzOwJwH1jQ3rPkeY1SQLDIf V5ncsDKBh7brcFZN/QHsT6bQ7A//i292YZpUwgsyY7OezAgE4RKB8OkCRvGdnHatkF tt3t8TH8Wa8Kg== From: "Lorenzo Stoakes (ARM)" Date: Thu, 06 Aug 2026 21:21:28 +0100 Subject: [PATCH v4 03/20] mm: introduce linear_anon_page_index() Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260806-b4-scalable-cow-virt-pgoff-v4-3-ab318a350404@kernel.org> References: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> In-Reply-To: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> To: Andrew Morton , David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Miaohe Lin , Naoya Horiguchi , Rik van Riel , Harry Yoo , Lance Yang , Kees Cook , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Usama Arif , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Peter Xu , Xu Xin , Chengming Zhou , Arnd Bergmann , Greg Kroah-Hartman , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Sven Schnelle , Alex Deucher , =?utf-8?q?Christian_K=C3=B6nig?= , David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Boris Brezillon , Steven Price , Liviu Dudau , Huang Rui , Matthew Auld , =?utf-8?q?Thomas_Hellstr=C3=B6m?= , Rodrigo Vivi , Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Jason Gunthorpe , John Hubbard , Muchun Song , Oscar Salvador , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Youngjun Park Cc: "Lorenzo Stoakes (ARM)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, intel-xe@lists.freedesktop.org, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=5143; i=ljs@kernel.org; h=from:subject:message-id; bh=0osG5+4gGXbzb2uNb/Bi6pWK7THgxYoP0n4wymDnQXc=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLJK3pzfVJinXbJJy/nNQz53BgNrRh5Xa0VBh62eG1ReH 6/zKSvuKGVhEONikBVTZHn+RXx/kEjYvM4L/m4wc1iZQIYwcHEKwERMzRn+Wb9/fIExmfVShC77 Xv0U34SPQRGpZZ2T2O7t+lC/UHF6P8P/aPc1J6025vz/2lAxZVvO3Y0Ne/nv/zG4q6cZKtB/pqa AAwA= X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 This function provides the anonymous equivalent of linear_page_index(), instead offsetting based on the anonymous page offset of the VMA. It is valid only for anonymous or MAP_PRIVATE file-backed mappings, in other words CoW mappings. For pure anon VMAs, this will be equal to linear_page_index(). Assert that both of these invariants are true In linear_anon_page_index() and implement the algorithm in __linear_anon_page_index(). Note that MAP_PRIVATE-/dev/zero mappings will satisfy vma_is_anonymous() but not fulfill this invariant, so when asserting this we check vma->vm_file to account for this. We do not update callsites yet, so no functional change intended. Also const-ify vma_is_anonymous() to make it compatible with the const-ified linear_anon_page_index(). While we're here, update linear_page_index() to be more succinct. VMA userland tests are also updated accordingly. Reviewed-by: Gregory Price (Meta) Signed-off-by: Lorenzo Stoakes (ARM) Acked-by: David Hildenbrand (Arm) --- include/linux/mm.h | 2 +- include/linux/pagemap.h | 40 +++++++++++++++++++++++++++++++++++++= --- tools/testing/vma/include/dup.h | 25 ++++++++++++++++++++++++- 3 files changed, 62 insertions(+), 5 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index a3368c542947..da36a6cc907c 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1556,7 +1556,7 @@ static inline void vma_desc_set_anonymous(struct vm_a= rea_desc *desc) desc->vm_ops =3D NULL; } =20 -static inline bool vma_is_anonymous(struct vm_area_struct *vma) +static inline bool vma_is_anonymous(const struct vm_area_struct *vma) { return !vma->vm_ops; } diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index c6fc783aaee5..0adfa6605653 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -1094,10 +1094,44 @@ static inline pgoff_t linear_page_delta(const struc= t vm_area_struct *vma, static inline pgoff_t linear_page_index(const struct vm_area_struct *vma, const unsigned long address) { - pgoff_t pgoff; + return linear_page_delta(vma, address) + vma_start_pgoff(vma); +} + +static inline pgoff_t __linear_anon_page_index(const struct vm_area_struct= *vma, + const unsigned long address) +{ + return linear_page_delta(vma, address) + vma_start_anon_pgoff(vma); +} + +/** + * linear_anon_page_index() - Determine the absolute anonymous page offset= of + * @address within @vma. + * @vma: An anonymous or MAP_PRIVATE file-backed VMA in which @address res= ides. + * @address: The address whose absolute page offset is required. + * + * This returns the anonymous page offset of @address, which is the page o= ffset + * the address possessed at the time the VMA was first faulted. + * + * For anonymous mappings, this returns the same value as linear_page_inde= x(). + * + * For MAP_PRIVATE file-backed mappings, this returns the anonymous page o= ffset + * of @address, which is the page offset the address possessed at the time= the + * VMA was first faulted. + * + * It is not valid to call this function for shared file-backed mappings. + * + * Returns: The absolute anonymous page offset of @address within @vma. + */ +static inline pgoff_t linear_anon_page_index(const struct vm_area_struct *= vma, + const unsigned long address) +{ + const pgoff_t pgoff =3D __linear_anon_page_index(vma, address); + + VM_WARN_ON_ONCE(!vma_is_cow_mapping(vma)); + /* Account for MAP_PRIVATE-/dev/zero which is only semi-anonymous. */ + if (vma_is_anonymous(vma) && !vma->vm_file) + VM_WARN_ON_ONCE(pgoff !=3D linear_page_index(vma, address)); =20 - pgoff =3D linear_page_delta(vma, address); - pgoff +=3D vma_start_pgoff(vma); return pgoff; } =20 diff --git a/tools/testing/vma/include/dup.h b/tools/testing/vma/include/du= p.h index 40ad83936b28..4c58487b764e 100644 --- a/tools/testing/vma/include/dup.h +++ b/tools/testing/vma/include/dup.h @@ -1428,7 +1428,7 @@ static inline void vma_iter_set(struct vma_iterator *= vmi, unsigned long addr) mas_set(&vmi->mas, addr); } =20 -static inline bool vma_is_anonymous(struct vm_area_struct *vma) +static inline bool vma_is_anonymous(const struct vm_area_struct *vma) { return !vma->vm_ops; } @@ -1621,3 +1621,26 @@ static inline pgprot_t vma_get_page_prot(const struc= t vm_area_struct *vma) { return vma_flags_to_page_prot(vma->flags); } + +static inline pgoff_t __linear_anon_page_index(const struct vm_area_struct= *vma, + const unsigned long address) +{ + pgoff_t pgoff; + + pgoff =3D linear_page_delta(vma, address); + pgoff +=3D vma_start_anon_pgoff(vma); + return pgoff; +} + +static inline pgoff_t linear_anon_page_index(const struct vm_area_struct *= vma, + const unsigned long address) +{ + const pgoff_t pgoff =3D __linear_anon_page_index(vma, address); + + VM_WARN_ON_ONCE(!vma_is_cow_mapping(vma)); + /* Account for MAP_PRIVATE-/dev/zero which is only semi-anonymous. */ + if (vma_is_anonymous(vma) && !vma->vm_file) + VM_WARN_ON_ONCE(pgoff !=3D linear_page_index(vma, address)); + + return pgoff; +} --=20 2.55.0 From nobody Wed Sep 30 20:13:06 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B9FDF3D3317; Thu, 6 Aug 2026 20:23:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; 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Thu, 6 Aug 2026 20:23:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786047813; bh=GlrT7r3tcep46r6Il05ij5JS2SxeagPngYBWHI1YDNw=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=EoEPZN1zYAkHbM1/HZ59R4SYuJ0kgr3s6twz6mViFc4pPHD2eOj4FlMUGCLkQYtoA fbOjc1ObmaiC5Fvp4F4F4sEGCxfMHu8CpqnY9UkX9t65/RJPvve1cIM6J14pWhWSIg dovnGA7O72WCJCrxNzM4MhVdhoqmzD1ZkT9jGwy6thH9LcjGcxTmN85p3XRCthcIOz 9/2A5+aVmLxBspPX4KvQ4RKFyT5cINyhuSH1ETm2C2yi1ZC0x/YHEhBeXEyP3REWQW hfGbQgp5itsouInFdRcnEDAVzu1N2FrH00x+jldbo49ZvuO6+SflbXjm8tKAng8oV7 E0+VQJF9G3bAw== From: "Lorenzo Stoakes (ARM)" Date: Thu, 06 Aug 2026 21:21:29 +0100 Subject: [PATCH v4 04/20] mm: abstract vma_address() and introduce vma_anon_address() Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260806-b4-scalable-cow-virt-pgoff-v4-4-ab318a350404@kernel.org> References: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> In-Reply-To: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> To: Andrew Morton , David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Miaohe Lin , Naoya Horiguchi , Rik van Riel , Harry Yoo , Lance Yang , Kees Cook , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Usama Arif , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Peter Xu , Xu Xin , Chengming Zhou , Arnd Bergmann , Greg Kroah-Hartman , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Sven Schnelle , Alex Deucher , =?utf-8?q?Christian_K=C3=B6nig?= , David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Boris Brezillon , Steven Price , Liviu Dudau , Huang Rui , Matthew Auld , =?utf-8?q?Thomas_Hellstr=C3=B6m?= , Rodrigo Vivi , Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Jason Gunthorpe , John Hubbard , Muchun Song , Oscar Salvador , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Youngjun Park Cc: "Lorenzo Stoakes (ARM)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, intel-xe@lists.freedesktop.org, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=3692; i=ljs@kernel.org; h=from:subject:message-id; bh=TcLlQnmra6maBGHXmsGw4bE6RvgdQMZRWpLIfm3Ze4w=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLJK3pxfv5nv281PeyXv5/f0Bj7wnvh4UtjbB0rCvzbP1 4u0y/x5qaOUhUGMi0FWTJHl+Rfx/UEiYfM6L/i7wcxhZQIZwsDFKQAXKWJkeNCeNjl5q85n2UfH w6IXMD5/Y1J7Ty9/5SeO5O8344p2ZDMyvG3unb1bcxsXz4KLxduOLfIV5GNdXtIgO32tmumScyU x/AA= X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 Introduce __vma_address() which abstracts the VMA start page offset field as pgoff_start, then update vma_address() to use it. Then introduce vma_anon_address() which does the equivalent of vma_address(), only using the anonymous page offset of the VMA rather than the file-backed one. Also add an assert to ensure that the function is not called for mappings which are file-backed but not MAP_PRIVATE to ensure it is only used in the correct places. This will be necessary for determining the address of a folio's index within a VMA when the folio belongs to a MAP_PRIVATE file-backed VMA but has been CoW'd, and thus is anonymous, once the anonymous VMA page offset field is used for the reverse mapping. No callers are updated, so no functional change intended. Acked-by: David Hildenbrand (Arm) Signed-off-by: Lorenzo Stoakes (ARM) --- mm/internal.h | 49 +++++++++++++++++++++++++++++++++++++------------ 1 file changed, 37 insertions(+), 12 deletions(-) diff --git a/mm/internal.h b/mm/internal.h index a75a1344e9ba..10b6662be8ed 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -1005,19 +1005,9 @@ void mlock_drain_remote(int cpu); =20 extern pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma); =20 -/** - * vma_address - Find the virtual address a page range is mapped at - * @vma: The vma which maps this object. - * @pgoff: The page offset within its object. - * @nr_pages: The number of pages to consider. - * - * If any page in this range is mapped by this VMA, return the first addre= ss - * where any of these pages appear. Otherwise, return -EFAULT. - */ -static inline unsigned long vma_address(const struct vm_area_struct *vma, - pgoff_t pgoff, unsigned long nr_pages) +static inline unsigned long __vma_address(const struct vm_area_struct *vma, + pgoff_t pgoff, pgoff_t pgoff_start, unsigned long nr_pages) { - const pgoff_t pgoff_start =3D vma_start_pgoff(vma); unsigned long address; =20 if (pgoff >=3D pgoff_start) { @@ -1035,6 +1025,41 @@ static inline unsigned long vma_address(const struct= vm_area_struct *vma, return address; } =20 +/** + * vma_address - Find the virtual address a page range is mapped at. + * @vma: The vma which maps this object. + * @pgoff: The page offset within its object. + * @nr_pages: The number of pages to consider. + * + * If any page in this range is mapped by this VMA, return the first addre= ss + * where any of these pages appear. Otherwise, return -EFAULT. + */ +static inline unsigned long vma_address(const struct vm_area_struct *vma, + pgoff_t pgoff, unsigned long nr_pages) +{ + return __vma_address(vma, pgoff, vma_start_pgoff(vma), nr_pages); +} + +/** + * vma_anon_address - Find the address an anonymous folio with index @pgof= f_anon + * is mapped at. + * @vma: The vma which maps this object. + * @pgoff_anon: The anonymous page index belonging to the folio. + * @nr_pages: The number of pages to consider. + * + * This is only valid for anonymous or MAP_PRIVATE-mapped file-backed VMAs. + * + * Returns: If any page in this range is mapped by this VMA, return the fi= rst + * address where any of these pages appear. Otherwise, return -EFAULT. + */ +static inline unsigned long vma_anon_address(const struct vm_area_struct *= vma, + pgoff_t pgoff_anon, unsigned long nr_pages) +{ + VM_WARN_ON_ONCE(!vma_is_cow_mapping(vma)); + + return __vma_address(vma, pgoff_anon, vma_start_anon_pgoff(vma), nr_pages= ); +} + /* * Then at what user virtual address will none of the range be found in vm= a? * Assumes that vma_address() already returned a good starting address. --=20 2.55.0 From nobody Wed Sep 30 20:13:06 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B12454D8D83; Thu, 6 Aug 2026 20:23:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786047837; cv=none; b=G0R9bZDrMSybIbOBdA/+028bElfdIc7deMl6BglHXfGQZO+agpykcn4eAWpCeME0zfysWsrreu759N8U0LPbZ4tfF2r1luqWHpccBb1WpvDxlkJmlIh8j0AufCjI1yI8ndT3noKNO+0EEQROst7nbFEpzdMhKy5WNrCqe9/+Rr0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786047837; c=relaxed/simple; bh=n0kfl3sX7UAIKHIjCWNuf6tCoy4kVBTkNam6LpgmDSU=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=WCRcOzT/9TWaP//xN7OvNqIks8zEi6S2h8uaATjiTiIP0Ldpl3WG9D2i3ww3kMotndkGl56oUtgEK6UkOzX8vnAN8ZFfVlwiQUC5LyTJXJpqoh62Q3Fty4suaepWbMRbeeE+Otny2MakNzQCRc6ySSEcy+LBBxU60Hbf74iB5jQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MmRVMcEe; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="MmRVMcEe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E47601F00A3A; Thu, 6 Aug 2026 20:23:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786047834; bh=7Nmbnq0r/tdkn7LzRpvbEkYwmsG/p8Yg0FdX7/Lw0rs=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=MmRVMcEeke8BjN31Rb0/r5myJ1BpKgvkvJfkwKHqBm5coJ9gj6rtuhKQ+tC9UB3Ag yiLLYr0VOLFl6xOwI18COwsR+5i8NSN+kzUzrcrvBRVpFwpdrZ++efgxEfNe+RlrSG /cd+OJHUGUZOb0HJ194nrElF/EGJe4HtJ3N+XGk69H7fTMYtlVuTBUBEYH2A+bziNd B04HmW6LylmuwA6SwXA80N2i4S+JyUblqvN34SlHE6XUbK7DvgRisD25b1gKvUWkRq ywkUAyOSQO7kX5DoyqY1/dW/DMHAbovwCV2uYSh1uoOfPFcEO+uGbAWdA8JjzpYQDR N91T4jABgdjIQ== From: "Lorenzo Stoakes (ARM)" Date: Thu, 06 Aug 2026 21:21:30 +0100 Subject: [PATCH v4 05/20] mm: update print_bad_page_map() to show anon index if appropriate Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260806-b4-scalable-cow-virt-pgoff-v4-5-ab318a350404@kernel.org> References: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> In-Reply-To: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> To: Andrew Morton , David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Miaohe Lin , Naoya Horiguchi , Rik van Riel , Harry Yoo , Lance Yang , Kees Cook , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Usama Arif , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Peter Xu , Xu Xin , Chengming Zhou , Arnd Bergmann , Greg Kroah-Hartman , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Sven Schnelle , Alex Deucher , =?utf-8?q?Christian_K=C3=B6nig?= , David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Boris Brezillon , Steven Price , Liviu Dudau , Huang Rui , Matthew Auld , =?utf-8?q?Thomas_Hellstr=C3=B6m?= , Rodrigo Vivi , Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Jason Gunthorpe , John Hubbard , Muchun Song , Oscar Salvador , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Youngjun Park Cc: "Lorenzo Stoakes (ARM)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, intel-xe@lists.freedesktop.org, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=2529; i=ljs@kernel.org; h=from:subject:message-id; bh=n0kfl3sX7UAIKHIjCWNuf6tCoy4kVBTkNam6LpgmDSU=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLJK3px//F1mabFgwLH5d36tUp/vuOde9fP0mn/Pz7aus T/btlqpq6OUhUGMi0FWTJHl+Rfx/UEiYfM6L/i7wcxhZQIZwsDFKQATEVjE8E9xhfb8e4cF1/75 uV9j7q7QY580ff+/Fbq5ZW8sh+O1Qu/bDP+r0zsiF9z+q3Tq0YsL8oKHF3POfxV4RDBgWZDckXZ byd2MAA== X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 If the VMA is a CoW mapping page offset may differ from anon page offset, indicating different positions in the relevant rmap trees. Update print_bad_page_map() to reflect that - if the mapping is non-CoW or the indexes match, then output only one index as before, otherwise output both with (file) or (anon) suffixes to reflect which is which. It's not possible to give only one index as there is no folio available to perform folio_test_anon() upon (the page table entry is bad so this is unavailable). This is potentially useful debugging information and matches the existing page offset provided. Use the raw __linear_anon_page_index() function so as to always output this value regardless of whether the mapping is file-backed or not and to avoid asserts that shouldn't apply here. Acked-by: David Hildenbrand (Arm) Reviewed-by: Gregory Price (Meta) Signed-off-by: Lorenzo Stoakes (ARM) --- mm/memory.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index e1349e18f046..3bd3616b27d2 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -631,13 +631,14 @@ static void print_bad_page_map(struct vm_area_struct = *vma, { struct address_space *mapping; char entry_str[PTVAL_STR_MAX]; - pgoff_t index; + pgoff_t index, anon_index; =20 if (is_bad_page_map_ratelimited()) return; =20 mapping =3D vma->vm_file ? vma->vm_file->f_mapping : NULL; index =3D linear_page_index(vma, addr); + anon_index =3D __linear_anon_page_index(vma, addr); =20 ptval_bytes_to_hex_str(entry_str, sizeof(entry_str), entry, entry_size); pr_alert("BUG: Bad page map in process %s %s:%s", current->comm, @@ -645,8 +646,14 @@ static void print_bad_page_map(struct vm_area_struct *= vma, __print_bad_page_map_pgtable(vma->vm_mm, addr); if (page) dump_page(page, "bad page map"); - pr_alert("addr:%px vm_flags:%08lx anon_vma:%px mapping:%px index:%lx\n", - (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index); + pr_alert("addr:%px vm_flags:%08lx anon_vma:%px mapping:%px", + (void *)addr, vma->vm_flags, vma->anon_vma, mapping); + if (!vma_is_cow_mapping(vma) || index =3D=3D anon_index) { + pr_cont(" index:%lx\n", index); + } else { + pr_cont(" index:%lx (file) %lx (anon)\n", index, anon_index); + } + pr_alert("file:%pD fault:%ps mmap:%ps mmap_prepare: %ps read_folio:%ps\n", vma->vm_file, vma->vm_ops ? vma->vm_ops->fault : NULL, --=20 2.55.0 From nobody Wed Sep 30 20:13:06 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 651023E638E; Thu, 6 Aug 2026 20:24:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786047856; cv=none; b=MkUyQWyHQXBnn2Xc9WkKCz6/QckDamtepjtPSbT6pm9bNHBAeBrWdFGTawtwuZUrQUPAGkQvJfSz6k0L+/QevX5OflyRCvpAa0IEo8GVbnj37g4LMcCo2ttbilhN+h75Rlonbomc3rzMXhhtRNP2igbs61kG9Y/ePyhvGglMgbs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786047856; c=relaxed/simple; bh=p77ev8vuIe2NzptTm2ieSg/F7FGTlLmZaKMePPxwgJc=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=TRn2yvrhMSvADJuzpEzOph3X+HMjeiLKoymgtXFpcWjCZtMNlYk/3iJqkGTV2u49noZzF6LR8EhECdqEMYijf8z4nf1yk2d/eZdBZehTOHaRGde/OPSzURWtmm1oD5Rdr8f4jWQlKcesfC41Neer5bAgZ9pyDwUiKRLbWbTxkaU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=c3XXj1bR; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="c3XXj1bR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 968DC1F000E9; Thu, 6 Aug 2026 20:23:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786047855; bh=jHeRoJJr2O8/TaKftY2r1DUlL3KME6EykG7g/IHvkjk=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=c3XXj1bR+rEnT/BtWc8+4gCm67erHhtNx3GA6VFgwz7w6wd9mgBBiUlFHxXfVKFWT dRICzU7QXVIfwJ0It16BrNMvwYmDcmcTPVxZd4SkL8I0srdUVisQY3iVzu9wvtjNpx 3nSou3Ft5lfOAKOrEZA1Kpf6oMwXxduF4t6pFIq36xignbklTqXkWzX3dfhIrw82eO uTuNgn0IBkUtm/OhbB8lCWXCWfo7S88g/u2duMieT+zuKi+4pmAZVxWrxw31+h7V+W 3fAnT09aQlkK3luL0Xk1M16c0/D35GAxaOJ7psGpSAGE0jXpfsN2zLoCXNCr9tJnXU MRs6a0OcMRtXg== From: "Lorenzo Stoakes (ARM)" Date: Thu, 06 Aug 2026 21:21:31 +0100 Subject: [PATCH v4 06/20] mm: introduce and use vma_filebacked_address() Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260806-b4-scalable-cow-virt-pgoff-v4-6-ab318a350404@kernel.org> References: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> In-Reply-To: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> To: Andrew Morton , David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Miaohe Lin , Naoya Horiguchi , Rik van Riel , Harry Yoo , Lance Yang , Kees Cook , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Usama Arif , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Peter Xu , Xu Xin , Chengming Zhou , Arnd Bergmann , Greg Kroah-Hartman , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Sven Schnelle , Alex Deucher , =?utf-8?q?Christian_K=C3=B6nig?= , David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Boris Brezillon , Steven Price , Liviu Dudau , Huang Rui , Matthew Auld , =?utf-8?q?Thomas_Hellstr=C3=B6m?= , Rodrigo Vivi , Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Jason Gunthorpe , John Hubbard , Muchun Song , Oscar Salvador , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Youngjun Park Cc: "Lorenzo Stoakes (ARM)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, intel-xe@lists.freedesktop.org, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org, syzbot@syzkaller.appspotmail.com X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=4971; i=ljs@kernel.org; h=from:subject:message-id; bh=p77ev8vuIe2NzptTm2ieSg/F7FGTlLmZaKMePPxwgJc=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLJK3lwQj8zp7dmw5uymU93/Iyymd3OyGpzNXZPPs+/zV 7nXN6Yt7ihlYRDjYpAVU2R5/kV8f5BI2LzOC/5uMHNYmUCGMHBxCsBEzqkyMnzjO6+7V/Tgsf+a vVJHTzRwpWQ+a9RrcnmVY3thc7Xa/x8M/8uOFm1U1vtsb1ugcMNfVPMv1+eO5Li2H8f+vpzEwZV 7jAMA X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 In cases where we know that the VMA is file-backed, use vma_filebacked_address() rather than vma_address(). This lays the foundation for using the anonymous page offset via vma_anon_address(). Also add an assert to ensure that the VMA whose address is required is not anonymous. No functional change intended. Tested-by: syzbot@syzkaller.appspotmail.com Acked-by: David Hildenbrand (Arm) Signed-off-by: Lorenzo Stoakes (ARM) --- mm/internal.h | 18 ++++++++++++++++++ mm/memory-failure.c | 4 ++-- mm/page_vma_mapped.c | 6 +++++- mm/rmap.c | 10 ++++++---- 4 files changed, 31 insertions(+), 7 deletions(-) diff --git a/mm/internal.h b/mm/internal.h index 10b6662be8ed..03145b8d0d56 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -1025,6 +1025,24 @@ static inline unsigned long __vma_address(const stru= ct vm_area_struct *vma, return address; } =20 +/** + * vma_filebacked_address - Find the virtual address a file-backed page ra= nge is + * mapped at. + * @vma: The vma which maps this object. + * @pgoff: The page offset within its object. + * @nr_pages: The number of pages to consider. + * + * Returns: If any page in this range is mapped by this VMA, return the fi= rst + * address where any of these pages appear. Otherwise, return -EFAULT. + */ +static inline unsigned long vma_filebacked_address(const struct vm_area_st= ruct *vma, + pgoff_t pgoff, unsigned long nr_pages) +{ + VM_WARN_ON_ONCE(vma_is_anonymous(vma)); + + return __vma_address(vma, pgoff, vma_start_pgoff(vma), nr_pages); +} + /** * vma_address - Find the virtual address a page range is mapped at. * @vma: The vma which maps this object. diff --git a/mm/memory-failure.c b/mm/memory-failure.c index aaf14608b30e..a8b03e2920ba 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -620,7 +620,7 @@ static void add_to_kill_fsdax(struct task_struct *tsk, = const struct page *p, struct vm_area_struct *vma, struct list_head *to_kill, pgoff_t pgoff) { - unsigned long addr =3D vma_address(vma, pgoff, 1); + unsigned long addr =3D vma_filebacked_address(vma, pgoff, 1); __add_to_kill(tsk, p, vma, to_kill, addr); } =20 @@ -2265,7 +2265,7 @@ static void add_to_kill_pgoff(struct task_struct *tsk, } =20 /* Check for pgoff not backed by struct page */ - tk->addr =3D vma_address(vma, pgoff, 1); + tk->addr =3D vma_filebacked_address(vma, pgoff, 1); tk->size_shift =3D PAGE_SHIFT; =20 if (tk->addr =3D=3D -EFAULT) diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c index d7670ba4147b..081e483cc7bf 100644 --- a/mm/page_vma_mapped.c +++ b/mm/page_vma_mapped.c @@ -356,6 +356,7 @@ unsigned long page_mapped_in_vma(const struct page *pag= e, struct vm_area_struct *vma) { const struct folio *folio =3D page_folio(page); + const pgoff_t pgoff =3D page_pgoff(folio, page); struct page_vma_mapped_walk pvmw =3D { .pfn =3D page_to_pfn(page), .nr_pages =3D 1, @@ -363,7 +364,10 @@ unsigned long page_mapped_in_vma(const struct page *pa= ge, .flags =3D PVMW_SYNC, }; =20 - pvmw.address =3D vma_address(vma, page_pgoff(folio, page), 1); + if (folio_test_anon(folio)) + pvmw.address =3D vma_address(vma, pgoff, 1); + else + pvmw.address =3D vma_filebacked_address(vma, pgoff, 1); if (pvmw.address =3D=3D -EFAULT) goto out; if (!page_vma_mapped_walk(&pvmw)) diff --git a/mm/rmap.c b/mm/rmap.c index ad820fe86f7d..5798427d007f 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -865,14 +865,15 @@ unsigned long page_address_in_vma(const struct folio = *folio, if (!vma->anon_vma || !anon_vma || vma->anon_vma->root !=3D anon_vma->root) return -EFAULT; + /* KSM folios don't reach here because of the !anon_vma check */ + return vma_address(vma, page_pgoff(folio, page), 1); } else if (!vma->vm_file) { return -EFAULT; } else if (vma->vm_file->f_mapping !=3D folio->mapping) { return -EFAULT; } =20 - /* KSM folios don't reach here because of the !anon_vma check */ - return vma_address(vma, page_pgoff(folio, page), 1); + return vma_filebacked_address(vma, page_pgoff(folio, page), 1); } =20 /* @@ -1321,7 +1322,7 @@ int pfn_mkclean_range(unsigned long pfn, unsigned lon= g nr_pages, pgoff_t pgoff, if (invalid_mkclean_vma(vma, NULL)) return 0; =20 - pvmw.address =3D vma_address(vma, pgoff, nr_pages); + pvmw.address =3D vma_filebacked_address(vma, pgoff, nr_pages); VM_BUG_ON_VMA(pvmw.address =3D=3D -EFAULT, vma); =20 return page_vma_mkclean_one(&pvmw); @@ -3100,7 +3101,8 @@ static void __rmap_walk_file(struct folio *folio, str= uct address_space *mapping, } lookup: mapping_rmap_tree_foreach(vma, mapping, pgoff_start, pgoff_end) { - unsigned long address =3D vma_address(vma, pgoff_start, nr_pages); + unsigned long address =3D vma_filebacked_address(vma, pgoff_start, + nr_pages); =20 VM_BUG_ON_VMA(address =3D=3D -EFAULT, vma); cond_resched(); --=20 2.55.0 From nobody Wed Sep 30 20:13:06 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 61DC03EB81B; Thu, 6 Aug 2026 20:24:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786047877; cv=none; b=S9NgNqfjysIVfprO7DLhiT8uO2IcgQQX38eh2n56qZCnniJgpA+mb3MdHUPGm3Hxe8QaSqNP7ny0fZAV9uBc9Uq9gGiRJB9toASAG9GPnSGnZo7oj0DyLSzxbGM13d5QoBcqeU9Db4L/dsMmCVhLnYlSIYZc5R8RwmSS+pfGoV4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786047877; c=relaxed/simple; bh=PoziUiui+lcnTYeWIW/Jvhg/0j22lR+6q9emZ8jY5cI=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=NsCkQpMc27W3GVxuvgHcinNFU0tUHzp46BtxMB9VC4QzJyHL5+Ej4TbpeYbXuwdm/75wy3kZ4mUgs+dhZDDlYomCTZ1h0OwE2Zz5kr1UC8QVbS0QN/wmgSWNPyzE9nN2ptcknAqLca4Rfr0mMWYcdfLeqe1oZlyJqn3SZMYsEIE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Fp1FKM+e; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Fp1FKM+e" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 891461F00A3A; Thu, 6 Aug 2026 20:24:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786047876; bh=bUF1A3bcjWsndOSThJkFooCv37wa4dNhaU3NAGA1ezE=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=Fp1FKM+eLh5lvZtVWpPOiPsPqz5lQD/UnC4C7x8GrG+pqXLW/xDbNogoYOsEm4YZu J/f+dynwiGc8gWGd5RQ3MrJ05O0wWbz3sXxb1KnEMnfYdqhj56aavycaVzEqQymBvT +nBrYxwuCHQRPay/Be9u2UYokJcnPUUrnqTkaf9Eq7yB4yGD9u4MhGFAKa9nYMKsds IjwbQYKfqX5Oy5/O/z5PV9eOEegPxQ9JmqxSx+1zAliK8CxVgGEiMmUib3mc3JPSdC 7XJtV8wRQBXn0QDAnVa54BcLBuDpq9ttQsttWkB+QC1JhAbhVJmn3Y3EQjqb6mMR3v tpB3HXYshyITw== From: "Lorenzo Stoakes (ARM)" Date: Thu, 06 Aug 2026 21:21:32 +0100 Subject: [PATCH v4 07/20] mm/vma: fix self-merge check in copy_vma() Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260806-b4-scalable-cow-virt-pgoff-v4-7-ab318a350404@kernel.org> References: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> In-Reply-To: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> To: Andrew Morton , David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Miaohe Lin , Naoya Horiguchi , Rik van Riel , Harry Yoo , Lance Yang , Kees Cook , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Usama Arif , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Peter Xu , Xu Xin , Chengming Zhou , Arnd Bergmann , Greg Kroah-Hartman , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Sven Schnelle , Alex Deucher , =?utf-8?q?Christian_K=C3=B6nig?= , David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Boris Brezillon , Steven Price , Liviu Dudau , Huang Rui , Matthew Auld , =?utf-8?q?Thomas_Hellstr=C3=B6m?= , Rodrigo Vivi , Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Jason Gunthorpe , John Hubbard , Muchun Song , Oscar Salvador , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Youngjun Park Cc: "Lorenzo Stoakes (ARM)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, intel-xe@lists.freedesktop.org, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=5496; i=ljs@kernel.org; h=from:subject:message-id; bh=PoziUiui+lcnTYeWIW/Jvhg/0j22lR+6q9emZ8jY5cI=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLJK3lzoWL7y96q3d3Zdrt2x0uQKZ88B2drsOjEHpQOuv 8XSnnKwd5SyMIhxMciKKbI8/yK+P0gkbF7nBX83mDmsTCBDGLg4BWAiptkM/6xsazxa/k0wrKzc VMJzt/X0oYb0Xz6JW7Ovv9rouCO/lJ3hf/095+r1Fjr83dcapircTzyaImbTqLLy3IL1NzPZSlR v8gEA X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 The existing logic is very confusing so improve things. Firstly rename the confusing faulted_in_anon_vma variable to can_self_merge and update this when the page offset is updated. What is being checked for is a 'self-merge' - that is between the VMA being remapped and its prior VMA (remember that this is copy_vma() - if a non-MREMAP_DONTUNMAP remap the original VMA is only removed afterwards). This can happen if the VMA is moved immediately adjacent to itself, either before or after it: |----------------|----------------| | | | v | v |...............||---------------||...............| | new || old || new | |...............||---------------||---------------| In these cases the old VMA is simply expanded to cover the new range. It is also possible for the move to both self-merge and merge with a prior VMA if it is placed between a preceding VMA and its old self: |---------------| | | v | |---------------||...............||---------------| | prev || new || old | |---------------||...............||---------------| In this case, the old VMA is removed and 'prev' is expanded and replaces it. Since copy_vma_and_data() which calls copy_vma() intends to reference the old VMA after the merge, it must have this pointer updated. This kind of self-merge is not possible with a succeeding merge, as the merge always prefers to expand the preceding VMA if possible. copy_vma() accounts for this by explicitly checking to see if a self-merge occurred and updating the vmap pointer if so. However it incorrect did so even for a subsequent merge (this is simply a noop so it had no impact). So change this to only check for the case which matters - a backwards merge - and rearrange the parameters to make it clearer we're doing that - i.e. check new_vma->vm_start < old_vma_start (having already renamed vma_start to old_vma_start to make it clear this is the previous VMA). Also update the existing wall-of-text comment to be a lot clearer. While we're here, replace the VM_BUG_ON_VMA() with a VM_WARN_ON_ONCE_VMA() and update the VMA userland tests accordingly. No functional change intended. Signed-off-by: Lorenzo Stoakes (ARM) Acked-by: David Hildenbrand (Arm) --- mm/vma.c | 35 ++++++++++++++++------------------- tools/testing/vma/vma_internal.h | 1 + 2 files changed, 17 insertions(+), 19 deletions(-) diff --git a/mm/vma.c b/mm/vma.c index b5bc3eec961c..18c8f2546765 100644 --- a/mm/vma.c +++ b/mm/vma.c @@ -1911,10 +1911,10 @@ struct vm_area_struct *copy_vma(struct vm_area_stru= ct **vmap, bool *need_rmap_locks) { struct vm_area_struct *vma =3D *vmap; - unsigned long vma_start =3D vma->vm_start; + unsigned long old_vma_start =3D vma->vm_start; struct mm_struct *mm =3D vma->vm_mm; struct vm_area_struct *new_vma; - bool faulted_in_anon_vma =3D true; + bool can_self_merge =3D false; VMA_ITERATOR(vmi, mm, addr); VMG_VMA_STATE(vmg, &vmi, NULL, vma, addr, addr + len); =20 @@ -1924,7 +1924,7 @@ struct vm_area_struct *copy_vma(struct vm_area_struct= **vmap, */ if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) { pgoff =3D addr >> PAGE_SHIFT; - faulted_in_anon_vma =3D false; + can_self_merge =3D true; } =20 /* @@ -1944,24 +1944,21 @@ struct vm_area_struct *copy_vma(struct vm_area_stru= ct **vmap, new_vma =3D vma_merge_copied_range(&vmg); =20 if (new_vma) { - /* - * Source vma may have been merged into new_vma - */ - if (unlikely(vma_start >=3D new_vma->vm_start && - vma_start < new_vma->vm_end)) { + /* Self-merged and VMA replaced. */ + if (unlikely(new_vma->vm_start < old_vma_start && + new_vma->vm_end > old_vma_start)) { /* - * The only way we can get a vma_merge with - * self during an mremap is if the vma hasn't - * been faulted in yet and we were allowed to - * reset the dst vma->vm_pgoff to the - * destination address of the mremap to allow - * the merge to happen. mremap must change the - * vm_pgoff linearity between src and dst vmas - * (in turn preventing a vma_merge) to be - * safe. It is only safe to keep the vm_pgoff - * linear if there are no pages mapped yet. + * The only way a VMA can both self-merge and be + * replaced is if the remap places the new VMA + * immediately prior to its old self ('next') and + * immediately after another VMA ('prev') causing the + * next to be removed and prev to be expanded to cover + * the entire range. + * + * This should only be possible if the page offset was + * updated, i.e. the VMA is unfaulted. */ - VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma); + VM_WARN_ON_ONCE_VMA(!can_self_merge, new_vma); *vmap =3D vma =3D new_vma; } *need_rmap_locks =3D diff --git a/tools/testing/vma/vma_internal.h b/tools/testing/vma/vma_inter= nal.h index 4f6c5666ac07..8a48b231aa7a 100644 --- a/tools/testing/vma/vma_internal.h +++ b/tools/testing/vma/vma_internal.h @@ -53,6 +53,7 @@ typedef __bitwise unsigned int vm_fault_t; =20 #define VM_WARN_ON(_expr) (WARN_ON(_expr)) #define VM_WARN_ON_ONCE(_expr) (WARN_ON_ONCE(_expr)) +#define VM_WARN_ON_ONCE_VMA(_expr, _vma) (WARN_ON_ONCE(_expr)) #define VM_WARN_ON_VMG(_expr, _vmg) (WARN_ON(_expr)) #define VM_BUG_ON(_expr) (BUG_ON(_expr)) #define VM_BUG_ON_VMA(_expr, _vma) (BUG_ON(_expr)) --=20 2.55.0 From nobody Wed Sep 30 20:13:06 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2650A363C77; Thu, 6 Aug 2026 20:24:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786047898; cv=none; b=O3GXfMrjkbw7wbuRqzsXPSIA33u1Jm1nt+MNTSC3dgC4sYaYLCC2nKdP83MtbuWZDqxPDOfAgm3c51TXIeOBO8Azgn9G1ClC+vHwctyDyQbN4CG8R1+TIg4WuZF/d4PvlATnQ85JqojGcEh6+bJRqCxVFbf0/COsvKdT2Uz7TZU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786047898; c=relaxed/simple; bh=zAtkjtetOPzY9ZCvVmUG7AAWKdJxJJDvCD2O0e7vMx0=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=qIO9RcOssN5Yrf9LLryJVsbHAm5pYuXQW42aeMm8jcKkskPNHYGM8oIxPKbgLw7/Kh02rLDJhR9HOKmsXRM8Q9y4bIxY4fZudXrqrUr9pEmIdIqB6f5zhad/abCcMeOkIAoXYNC3IDG+b4NrNL+lW5Vv4iMzLfhYgTMYIYv9b6M= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=it9dz7Pp; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="it9dz7Pp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 790AF1F000E9; Thu, 6 Aug 2026 20:24:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786047896; bh=PZwB0kepe8H+9w+FQhSK8VcxxvTZJ+pddqATUquP6OA=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=it9dz7PpsOSLESWT8uwHQovZ/mvj67amjGnQ8gZRPpDJKKbsnlU1uSsY/1dLyMCXm ba2y3JIf6FNk78aRrHS3h90Kr6M/zps4OruCQfkUBqboYjLqG80QbIkNDmz6dh6n8W mQQ7kUuDbG1OKAQDp8JZG8nSMi9RF7HeuYHqCmUPZ7KC4oQGZ4ajukmQ1MKQXFGu9T da2t8ur2ROVD5M9cVUNxBMGHOP2O4TEhTXJ1wpkcPwiLqj38eL+I6wV+tXv9o1uUMe DYXAowI7nzDQEDDFNPCE9gJ9ol8ld4fAe+ZaBEx3jqA02FiOHvjBi2vKern8w0XtHY 30sTdJBOieI1Q== From: "Lorenzo Stoakes (ARM)" Date: Thu, 06 Aug 2026 21:21:33 +0100 Subject: [PATCH v4 08/20] tools/testing/vma: add tests for copy_vma() self-merge Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260806-b4-scalable-cow-virt-pgoff-v4-8-ab318a350404@kernel.org> References: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> In-Reply-To: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> To: Andrew Morton , David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Miaohe Lin , Naoya Horiguchi , Rik van Riel , Harry Yoo , Lance Yang , Kees Cook , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Usama Arif , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Peter Xu , Xu Xin , Chengming Zhou , Arnd Bergmann , Greg Kroah-Hartman , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Sven Schnelle , Alex Deucher , =?utf-8?q?Christian_K=C3=B6nig?= , David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Boris Brezillon , Steven Price , Liviu Dudau , Huang Rui , Matthew Auld , =?utf-8?q?Thomas_Hellstr=C3=B6m?= , Rodrigo Vivi , Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Jason Gunthorpe , John Hubbard , Muchun Song , Oscar Salvador , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Youngjun Park Cc: "Lorenzo Stoakes (ARM)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, intel-xe@lists.freedesktop.org, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=2542; i=ljs@kernel.org; h=from:subject:message-id; bh=zAtkjtetOPzY9ZCvVmUG7AAWKdJxJJDvCD2O0e7vMx0=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLJK3lyInr43/OZH39eLbKZLSetMY+o5wy2lUrZZ6kDq2 iXWu51ZO0pZGMS4GGTFFFmefxHfHyQSNq/zgr8bzBxWJpAhDFycAjARqXuMDFeKHKTsNJ7EiaUb PnS1qhWtVE7Z9SV+XdrEE9Ys0v9UVRgZHk67+SqfQVCz8MXRWQ25+bMnhjzuvfSe13jeba8t/kz ruAA= X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 Assert that a VMA can be moved backwards, forwards and between a preceding VMA and its old self. In the cases in which the VMA merges only with itself expect that to be achieved by expanding its old self, so assert that these function correctly. However in the case of a merge between a preceding VMA and itself the original VMA is removed, so assert that the preceding VMA replaces the one passed in as vmap and the merge is as expected. Signed-off-by: Lorenzo Stoakes (ARM) Acked-by: David Hildenbrand (Arm) --- tools/testing/vma/tests/vma.c | 46 +++++++++++++++++++++++++++++++++++++++= +++- 1 file changed, 45 insertions(+), 1 deletion(-) diff --git a/tools/testing/vma/tests/vma.c b/tools/testing/vma/tests/vma.c index 754a2da06321..0d40d7ba2181 100644 --- a/tools/testing/vma/tests/vma.c +++ b/tools/testing/vma/tests/vma.c @@ -33,7 +33,51 @@ static bool test_copy_vma(void) struct mm_struct mm =3D {}; bool need_locks =3D false; VMA_ITERATOR(vmi, &mm, 0); - struct vm_area_struct *vma, *vma_new, *vma_next; + struct vm_area_struct *vma, *vma_prev, *vma_new, *vma_next, *vma_orig; + + /* Move forwards, adjacent to old self - self-merge. */ + + vma =3D alloc_and_link_vma(&mm, 0x1000, 0x2000, 1, vma_flags); + vma_set_anonymous(vma); + vma_orig =3D vma; + vma_new =3D copy_vma(&vma, 0x2000, 0x1000, 1, &need_locks); + ASSERT_EQ(vma_new, vma_orig); + ASSERT_EQ(vma, vma_orig); + ASSERT_EQ(vma_new->vm_start, 0x1000); + ASSERT_EQ(vma_new->vm_end, 0x3000); + + cleanup_mm(&mm, &vmi); + + /* Move backwards, adjacent to old self - self-merge. */ + + vma =3D alloc_and_link_vma(&mm, 0x2000, 0x3000, 2, vma_flags); + vma_set_anonymous(vma); + vma_orig =3D vma; + vma_new =3D copy_vma(&vma, 0x1000, 0x1000, 2, &need_locks); + ASSERT_EQ(vma_new, vma_orig); + ASSERT_EQ(vma, vma_orig); + ASSERT_EQ(vma_new->vm_start, 0x1000); + ASSERT_EQ(vma_new->vm_end, 0x3000); + + cleanup_mm(&mm, &vmi); + + /* + * Move backwards between prior VMA and old self - self-merge and vma + * updated to a new VMA. + */ + + vma_prev =3D alloc_and_link_vma(&mm, 0x1000, 0x2000, 1, vma_flags); + vma_set_anonymous(vma_prev); + vma =3D alloc_and_link_vma(&mm, 0x3000, 0x4000, 3, vma_flags); + vma_set_anonymous(vma); + vma_orig =3D vma; + vma_new =3D copy_vma(&vma, 0x2000, 0x1000, 3, &need_locks); + ASSERT_NE(vma_new, vma_orig); + ASSERT_EQ(vma_new, vma); + ASSERT_EQ(vma_new->vm_start, 0x1000); + ASSERT_EQ(vma_new->vm_end, 0x4000); + + cleanup_mm(&mm, &vmi); =20 /* Move backwards and do not merge. */ =20 --=20 2.55.0 From nobody Wed Sep 30 20:13:06 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 076C134E74D; Thu, 6 Aug 2026 20:25:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786047919; cv=none; b=aqrUIM+3tpKqe5EdMX6kTsnR/5xbmRz4bjRs17PNUTHx7tNN7KEuRPOwuHqnROyuKa84sGundx02qb7ISwUnipWwdDbbfiDQ5/cr05NzrU7MuXOJpB5gooy0AhvSev2Lf1Y0SuAAEF5//HMWZMYdyZz9hVzne0N5T8888XHadvM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786047919; c=relaxed/simple; bh=AyIYrhzUHJF8dUestntVqmDUqdrez55Qr20v7Ceu/jA=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=mBGZesmdqA4qLwqJO6esscnl72gL1eX++nlvy4aDR1qzrHmjNVYKshWjkeBy7C83iUcZIwBIAC8wzss2NM8X5etO6hyjH1ZPmbgWrCsd1kW2ziGk+hdFZrfdIBVu7TeNouo432h8MLqwh64QOJy0z4Ws5WrDyloW7s5XyCx2Zeo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jyn1wWwn; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="jyn1wWwn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 341AC1F00A3D; Thu, 6 Aug 2026 20:24:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786047917; bh=oao9Xk4uxKSjDN12QXQzhenCGYwnNUJY+Ax5MPFwIgA=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=jyn1wWwnnSZmZGtMbWal5DVN09uA80dzqH+jTdZBK2c9aHbS8UX6uXJC31yIhjfkI X34d6flfVXmExy6Q5Iqkr5eFI1dbqNrK9Vj3GeziXy+VI1i8iH0IZYDdabTQBgqpLw 51UmpZ+Odp01c0O3WlD0MbavfrHd2cdGb2Qd1K7w+rpRwv8MU/WwEJJxkBWX7vT2wV bgvUszqoPE4S/danJFigNLXiAGHlllFRda6KFYDF29sfgqtH3iaHTqd1jU0HXwcTcG mNJgIVMGDGIo1iigKd7V3DxIQkW02z6aLgKnbc/JO/8CRh0E4k7VlcfrfUMBILx4U2 Aj5HjNsRCetaw== From: "Lorenzo Stoakes (ARM)" Date: Thu, 06 Aug 2026 21:21:34 +0100 Subject: [PATCH v4 09/20] mm: propagate VMA anonymous page offset on map, remap, split + merge Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260806-b4-scalable-cow-virt-pgoff-v4-9-ab318a350404@kernel.org> References: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> In-Reply-To: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> To: Andrew Morton , David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Miaohe Lin , Naoya Horiguchi , Rik van Riel , Harry Yoo , Lance Yang , Kees Cook , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Usama Arif , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Peter Xu , Xu Xin , Chengming Zhou , Arnd Bergmann , Greg Kroah-Hartman , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Sven Schnelle , Alex Deucher , =?utf-8?q?Christian_K=C3=B6nig?= , David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Boris Brezillon , Steven Price , Liviu Dudau , Huang Rui , Matthew Auld , =?utf-8?q?Thomas_Hellstr=C3=B6m?= , Rodrigo Vivi , Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Jason Gunthorpe , John Hubbard , Muchun Song , Oscar Salvador , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Youngjun Park Cc: "Lorenzo Stoakes (ARM)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, intel-xe@lists.freedesktop.org, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=20248; i=ljs@kernel.org; h=from:subject:message-id; bh=AyIYrhzUHJF8dUestntVqmDUqdrez55Qr20v7Ceu/jA=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLJK3lxgC1rVGhxuceb5bRPbP+oRzEaL9ii75iR9NTVgO Tk7rj24o5SFQYyLQVZMkeX5F/H9QSJh8zov+LvBzGFlAhnCwMUpABPZPZ3hn6V3NM8p3eiUYzW5 nXG3Nxxe/kF6aWBLo1Hsw4pgi4CzGxj+l7sfrF+Zz+Eru9+udNps3UrPMKfDawNdlj3f+GXDaaN 9vAA= X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 We must correctly update VMA anonymous page offset state on all VMA operations that would result in it changing, with special attention given to remapping. We cover most cases by simply updating vma_set_range() to do so (with a new anonymous page offset parameter), but also notably must update the merging and mapping logic to propagate this parameter correctly. The remap logic remains the same - we may update the anonymous page offset if the VMA is unfaulted, but now this applies to MAP_PRIVATE file-backed mappings too, so we update the code to reflect this. Note that we use __linear_anon_page_index() upon remap as the VMA may be shared, in order that we update the field consistently regardless of VMA type. Similarly, pass through anon page offset to the merge logic, updating the vma_merge_struct struct to propagate it, and also use __linear_anon_page_index() to obtain the anonymous page index so it can be safely used for both shared and MAP_PRIVATE file-backed mappings. In copy_vma(), the anonymous page offset is updated regardless of whether the mapping is a CoW mapping or not. This is both to keep the anonymous page offset consistent even for non-CoW mappings (it is set so should at least remain correct) and makes the logic cleaner. A self-merge however remains permitted only for mappings which can have a populated vma->anon_vma and do not require alignment on a separate file offset - that is pure anonymous VMAs, so only set can_self_merge if vma_is_anonymous(). Finally, we update insert_vm_struct() to correctly set the anonymous page offset on insertion of a VMA. We simply ensure state is correctly propagated here, so no functional changes are intended. Also update VMA userland tests to reflect this change. Acked-by: David Hildenbrand (Arm) Signed-off-by: Lorenzo Stoakes (ARM) --- mm/mremap.c | 6 ++-- mm/vma.c | 52 ++++++++++++++++++---------- mm/vma.h | 75 ++++++++++++++++++++++++-------------= ---- mm/vma_exec.c | 2 +- tools/testing/vma/shared.c | 3 +- tools/testing/vma/tests/merge.c | 4 ++- tools/testing/vma/tests/vma.c | 10 +++--- 7 files changed, 95 insertions(+), 57 deletions(-) diff --git a/mm/mremap.c b/mm/mremap.c index b64aa1f6e07e..9ea1707eafa5 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -1265,7 +1265,9 @@ static void unmap_source_vma(struct vma_remap_struct = *vrm) static int copy_vma_and_data(struct vma_remap_struct *vrm, struct vm_area_struct **new_vma_ptr) { - const unsigned long new_pgoff =3D linear_page_index(vrm->vma, vrm->addr); + const pgoff_t new_pgoff =3D linear_page_index(vrm->vma, vrm->addr); + const pgoff_t new_anon_pgoff =3D + __linear_anon_page_index(vrm->vma, vrm->addr); struct vm_area_struct *vma =3D vrm->vma; struct vm_area_struct *new_vma; unsigned long moved_len; @@ -1273,7 +1275,7 @@ static int copy_vma_and_data(struct vma_remap_struct = *vrm, PAGETABLE_MOVE(pmc, NULL, NULL, vrm->addr, vrm->new_addr, vrm->old_len); =20 new_vma =3D copy_vma(&vma, vrm->new_addr, vrm->new_len, new_pgoff, - &pmc.need_rmap_locks); + new_anon_pgoff, &pmc.need_rmap_locks); if (!new_vma) { vrm_uncharge(vrm); *new_vma_ptr =3D NULL; diff --git a/mm/vma.c b/mm/vma.c index 18c8f2546765..b55015952f0d 100644 --- a/mm/vma.c +++ b/mm/vma.c @@ -18,6 +18,7 @@ struct mmap_state { unsigned long addr; unsigned long end; pgoff_t pgoff; + pgoff_t anon_pgoff; unsigned long pglen; union { vm_flags_t vm_flags; @@ -46,13 +47,14 @@ struct mmap_state { bool file_doesnt_need_get :1; }; =20 -#define MMAP_STATE(name, mm_, vmi_, addr_, len_, pgoff_, vma_flags_, file_= ) \ +#define MMAP_STATE(name, mm_, vmi_, addr_, len_, pgoff_, anon_pgoff_, vma_= flags_, file_) \ struct mmap_state name =3D { \ .mm =3D mm_, \ .vmi =3D vmi_, \ .addr =3D addr_, \ .end =3D (addr_) + (len_), \ .pgoff =3D pgoff_, \ + .anon_pgoff =3D anon_pgoff_, \ .pglen =3D PHYS_PFN(len_), \ .vma_flags =3D vma_flags_, \ .file =3D file_, \ @@ -67,6 +69,7 @@ struct mmap_state { .end =3D (map_)->end, \ .vma_flags =3D (map_)->vma_flags, \ .pgoff =3D (map_)->pgoff, \ + .anon_pgoff =3D (map_)->anon_pgoff, \ .file =3D (map_)->file, \ .prev =3D (map_)->prev, \ .middle =3D vma_, \ @@ -82,10 +85,11 @@ static void __vma_set_range(struct vm_area_struct *vma,= unsigned long start, } =20 static void vma_set_range(struct vm_area_struct *vma, unsigned long start, - unsigned long end, pgoff_t pgoff) + unsigned long end, pgoff_t pgoff, pgoff_t anon_pgoff) { __vma_set_range(vma, start, end); vma_set_pgoff(vma, pgoff); + vma_set_anon_pgoff(vma, anon_pgoff); } =20 /* Was this VMA ever forked from a parent, i.e. maybe contains CoW mapping= s? */ @@ -812,7 +816,8 @@ static int commit_merge(struct vma_merge_struct *vmg) */ vma_adjust_trans_huge(vma, vmg->start, vmg->end, vmg->__adjust_middle_start ? vmg->middle : NULL); - vma_set_range(vma, vmg->start, vmg->end, vmg_start_pgoff(vmg)); + vma_set_range(vma, vmg->start, vmg->end, vmg_start_pgoff(vmg), + vmg_start_anon_pgoff(vmg)); vmg_adjust_set_range(vmg); vma_iter_store_overwrite(vmg->vmi, vmg->target); =20 @@ -982,6 +987,7 @@ static __must_check struct vm_area_struct *vma_merge_ex= isting_range( vmg->start =3D prev->vm_start; vmg->end =3D next->vm_end; vmg->pgoff =3D vma_start_pgoff(prev); + vmg->anon_pgoff =3D vma_start_anon_pgoff(prev); =20 /* * We already ensured anon_vma compatibility above, so now it's @@ -1000,6 +1006,7 @@ static __must_check struct vm_area_struct *vma_merge_= existing_range( */ vmg->start =3D prev->vm_start; vmg->pgoff =3D vma_start_pgoff(prev); + vmg->anon_pgoff =3D vma_start_anon_pgoff(prev); =20 if (!vmg->__remove_middle) vmg->__adjust_middle_start =3D true; @@ -1022,12 +1029,14 @@ static __must_check struct vm_area_struct *vma_merg= e_existing_range( if (vmg->__remove_middle) { vmg->end =3D next->vm_end; vmg->pgoff =3D vma_start_pgoff(next) - pglen; + vmg->anon_pgoff =3D vma_start_anon_pgoff(next) - pglen; } else { /* We shrink middle and expand next. */ vmg->__adjust_next_start =3D true; vmg->start =3D middle->vm_start; vmg->end =3D start; vmg->pgoff =3D vma_start_pgoff(middle); + vmg->anon_pgoff =3D vma_start_anon_pgoff(middle); } =20 err =3D dup_anon_vma(next, middle, &anon_dup); @@ -1137,6 +1146,7 @@ struct vm_area_struct *vma_merge_new_range(struct vma= _merge_struct *vmg) vmg->start =3D prev->vm_start; vmg->target =3D prev; vmg->pgoff =3D vma_start_pgoff(prev); + vmg->anon_pgoff =3D vma_start_anon_pgoff(prev); =20 /* * If this merge would result in removal of the next VMA but we @@ -1908,7 +1918,7 @@ static int vma_link(struct mm_struct *mm, struct vm_a= rea_struct *vma) */ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, unsigned long addr, unsigned long len, pgoff_t pgoff, - bool *need_rmap_locks) + pgoff_t anon_pgoff, bool *need_rmap_locks) { struct vm_area_struct *vma =3D *vmap; unsigned long old_vma_start =3D vma->vm_start; @@ -1919,12 +1929,16 @@ struct vm_area_struct *copy_vma(struct vm_area_stru= ct **vmap, VMG_VMA_STATE(vmg, &vmi, NULL, vma, addr, addr + len); =20 /* - * If anonymous vma has not yet been faulted, update new pgoff - * to match new location, to increase its chance of merging. + * If a vma has not yet been faulted, update its anonymous pgoff to + * match the new location to increase its chance of merging. */ - if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) { - pgoff =3D addr >> PAGE_SHIFT; - can_self_merge =3D true; + if (!vma->anon_vma) { + anon_pgoff =3D addr >> PAGE_SHIFT; + + if (vma_is_anonymous(vma)) { + pgoff =3D anon_pgoff; + can_self_merge =3D true; + } } =20 /* @@ -1940,6 +1954,7 @@ struct vm_area_struct *copy_vma(struct vm_area_struct= **vmap, return NULL; /* should never get here */ =20 vmg.pgoff =3D pgoff; + vmg.anon_pgoff =3D anon_pgoff; vmg.next =3D vma_iter_next_rewind(&vmi, NULL); new_vma =3D vma_merge_copied_range(&vmg); =20 @@ -1955,8 +1970,8 @@ struct vm_area_struct *copy_vma(struct vm_area_struct= **vmap, * next to be removed and prev to be expanded to cover * the entire range. * - * This should only be possible if the page offset was - * updated, i.e. the VMA is unfaulted. + * This should only be possible if the anonymous page + * offset was updated, i.e. the VMA is unfaulted. */ VM_WARN_ON_ONCE_VMA(!can_self_merge, new_vma); *vmap =3D vma =3D new_vma; @@ -1967,7 +1982,7 @@ struct vm_area_struct *copy_vma(struct vm_area_struct= **vmap, new_vma =3D vm_area_dup(vma); if (!new_vma) goto out; - vma_set_range(new_vma, addr, addr + len, pgoff); + vma_set_range(new_vma, addr, addr + len, pgoff, anon_pgoff); if (vma_dup_policy(vma, new_vma)) goto out_free_vma; if (anon_vma_clone(new_vma, vma, VMA_OP_REMAP)) @@ -2609,7 +2624,7 @@ static int __mmap_new_vma(struct mmap_state *map, str= uct vm_area_struct **vmap, if (is_anon) vma_set_anonymous(vma); =20 - vma_set_range(vma, map->addr, map->end, map->pgoff); + vma_set_range(vma, map->addr, map->end, map->pgoff, map->anon_pgoff); vma->flags =3D map->vma_flags; vma->vm_page_prot =3D map->page_prot; =20 @@ -2798,7 +2813,8 @@ static unsigned long __mmap_region(struct file *file,= unsigned long addr, struct vm_area_struct *vma =3D NULL; bool have_mmap_prepare =3D file && file->f_op->mmap_prepare; VMA_ITERATOR(vmi, mm, addr); - MMAP_STATE(map, mm, &vmi, addr, len, pgoff, vma_flags, file); + const pgoff_t anon_pgoff =3D addr >> PAGE_SHIFT; + MMAP_STATE(map, mm, &vmi, addr, len, pgoff, anon_pgoff, vma_flags, file); struct vm_area_desc desc =3D { .mm =3D mm, .file =3D file, @@ -2943,6 +2959,7 @@ int do_brk_flags(struct vma_iterator *vmi, struct vm_= area_struct *vma, unsigned long addr, unsigned long len, vma_flags_t vma_flags) { struct mm_struct *mm =3D current->mm; + const pgoff_t pgoff =3D addr >> PAGE_SHIFT; =20 /* * Check against address space limits by the changed size @@ -2967,7 +2984,7 @@ int do_brk_flags(struct vma_iterator *vmi, struct vm_= area_struct *vma, * occur after forking, so the expand will only happen on new VMAs. */ if (vma && vma->vm_end =3D=3D addr) { - VMG_STATE(vmg, mm, vmi, addr, addr + len, vma_flags, PHYS_PFN(addr)); + VMG_STATE(vmg, mm, vmi, addr, addr + len, vma_flags, pgoff, pgoff); =20 vmg.prev =3D vma; /* vmi is positioned at prev, which this mode expects. */ @@ -2987,7 +3004,7 @@ int do_brk_flags(struct vma_iterator *vmi, struct vm_= area_struct *vma, goto unacct_fail; =20 vma_set_anonymous(vma); - vma_set_range(vma, addr, addr + len, addr >> PAGE_SHIFT); + vma_set_range(vma, addr, addr + len, pgoff, pgoff); vma->flags =3D vma_flags; vma->vm_page_prot =3D vm_get_page_prot(vma_flags_to_legacy(vma_flags)); vma_start_write(vma); @@ -3379,6 +3396,7 @@ int insert_vm_struct(struct mm_struct *mm, struct vm_= area_struct *vma) WARN_ON_ONCE(vma->anon_vma); vma_set_pgoff(vma, vma->vm_start >> PAGE_SHIFT); } + vma_set_anon_pgoff(vma, vma->vm_start >> PAGE_SHIFT); =20 if (vma_link(mm, vma)) { if (vma_test(vma, VMA_ACCOUNT_BIT)) @@ -3434,7 +3452,7 @@ struct vm_area_struct *__install_special_mapping( =20 vma->vm_ops =3D ops; vma->vm_private_data =3D priv; - vma_set_range(vma, addr, addr + len, 0); + vma_set_range(vma, addr, addr + len, 0, addr >> PAGE_SHIFT); =20 ret =3D insert_vm_struct(mm, vma); if (ret) diff --git a/mm/vma.h b/mm/vma.h index 54ed7c744e3b..024fabe63560 100644 --- a/mm/vma.h +++ b/mm/vma.h @@ -104,6 +104,7 @@ struct vma_merge_struct { unsigned long start; unsigned long end; pgoff_t pgoff; + pgoff_t anon_pgoff; =20 union { /* Temporary while VMA flags are being converted. */ @@ -237,11 +238,6 @@ static inline bool vmg_nomem(struct vma_merge_struct *= vmg) return vmg->state =3D=3D VMA_MERGE_ERROR_NOMEM; } =20 -static inline pgoff_t vmg_start_pgoff(const struct vma_merge_struct *vmg) -{ - return vmg->pgoff; -} - static inline pgoff_t vmg_pages(const struct vma_merge_struct *vmg) { const unsigned long size =3D vmg->end - vmg->start; @@ -249,6 +245,11 @@ static inline pgoff_t vmg_pages(const struct vma_merge= _struct *vmg) return size >> PAGE_SHIFT; } =20 +static inline pgoff_t vmg_start_pgoff(const struct vma_merge_struct *vmg) +{ + return vmg->pgoff; +} + static inline pgoff_t vmg_end_pgoff(const struct vma_merge_struct *vmg) { return vmg_start_pgoff(vmg) + vmg_pages(vmg); @@ -283,6 +284,16 @@ static inline void vma_set_pgoff(struct vm_area_struct= *vma, pgoff_t pgoff) vma->vm_pgoff =3D pgoff; } =20 +static inline pgoff_t vmg_start_anon_pgoff(const struct vma_merge_struct *= vmg) +{ + return vmg->anon_pgoff; +} + +static inline pgoff_t vmg_end_anon_pgoff(const struct vma_merge_struct *vm= g) +{ + return vmg_start_anon_pgoff(vmg) + vmg_pages(vmg); +} + static inline void __vma_set_anon_pgoff(struct vm_area_struct *vma, pgoff_= t pgoff) { #ifdef CONFIG_64BIT @@ -301,44 +312,48 @@ static inline void vma_add_pgoff(struct vm_area_struc= t *vma, pgoff_t delta) { vma_assert_can_modify(vma); vma_set_pgoff(vma, vma_start_pgoff(vma) + delta); + vma_set_anon_pgoff(vma, vma_start_anon_pgoff(vma) + delta); } =20 static inline void vma_sub_pgoff(struct vm_area_struct *vma, pgoff_t delta) { vma_assert_can_modify(vma); vma_set_pgoff(vma, vma_start_pgoff(vma) - delta); -} + vma_set_anon_pgoff(vma, vma_start_anon_pgoff(vma) - delta); +} + +#define VMG_STATE(name, mm_, vmi_, start_, end_, vma_flags_, pgoff_, anon_= pgoff_) \ + struct vma_merge_struct name =3D { \ + .mm =3D mm_, \ + .vmi =3D vmi_, \ + .start =3D start_, \ + .end =3D end_, \ + .vma_flags =3D vma_flags_, \ + .pgoff =3D pgoff_, \ + .anon_pgoff =3D anon_pgoff_, \ + .state =3D VMA_MERGE_START, \ + } =20 -#define VMG_STATE(name, mm_, vmi_, start_, end_, vma_flags_, pgoff_) \ +#define VMG_VMA_STATE(name, vmi_, prev_, vma_, start_, end_) \ struct vma_merge_struct name =3D { \ - .mm =3D mm_, \ + .mm =3D vma_->vm_mm, \ .vmi =3D vmi_, \ + .prev =3D prev_, \ + .middle =3D vma_, \ + .next =3D NULL, \ .start =3D start_, \ .end =3D end_, \ - .vma_flags =3D vma_flags_, \ - .pgoff =3D pgoff_, \ + .vm_flags =3D vma_->vm_flags, \ + .pgoff =3D linear_page_index(vma_, start_), \ + .anon_pgoff =3D __linear_anon_page_index(vma_, start_), \ + .file =3D vma_->vm_file, \ + .anon_vma =3D vma_->anon_vma, \ + .policy =3D vma_policy(vma_), \ + .uffd_ctx =3D vma_->vm_userfaultfd_ctx, \ + .anon_name =3D anon_vma_name(vma_), \ .state =3D VMA_MERGE_START, \ } =20 -#define VMG_VMA_STATE(name, vmi_, prev_, vma_, start_, end_) \ - struct vma_merge_struct name =3D { \ - .mm =3D vma_->vm_mm, \ - .vmi =3D vmi_, \ - .prev =3D prev_, \ - .middle =3D vma_, \ - .next =3D NULL, \ - .start =3D start_, \ - .end =3D end_, \ - .vm_flags =3D vma_->vm_flags, \ - .pgoff =3D linear_page_index(vma_, start_), \ - .file =3D vma_->vm_file, \ - .anon_vma =3D vma_->anon_vma, \ - .policy =3D vma_policy(vma_), \ - .uffd_ctx =3D vma_->vm_userfaultfd_ctx, \ - .anon_name =3D anon_vma_name(vma_), \ - .state =3D VMA_MERGE_START, \ - } - #ifdef CONFIG_DEBUG_VM_MAPLE_TREE void validate_mm(struct mm_struct *mm); #else @@ -520,7 +535,7 @@ void unlink_file_vma_batch_add(struct unlink_vma_file_b= atch *vb, =20 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, unsigned long addr, unsigned long len, pgoff_t pgoff, - bool *need_rmap_locks); + pgoff_t anon_pgoff, bool *need_rmap_locks); =20 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma); =20 diff --git a/mm/vma_exec.c b/mm/vma_exec.c index 7af1260689b9..586c52155942 100644 --- a/mm/vma_exec.c +++ b/mm/vma_exec.c @@ -41,7 +41,7 @@ int relocate_vma_down(struct vm_area_struct *vma, unsigne= d long shift) unsigned long new_end =3D old_end - shift; VMA_ITERATOR(vmi, mm, new_start); VMG_STATE(vmg, mm, &vmi, new_start, old_end, EMPTY_VMA_FLAGS, - vma_start_pgoff(vma)); + vma_start_pgoff(vma), vma_start_anon_pgoff(vma)); struct vm_area_struct *next; struct mmu_gather tlb; PAGETABLE_MOVE(pmc, vma, vma, old_start, new_start, length); diff --git a/tools/testing/vma/shared.c b/tools/testing/vma/shared.c index bea9ea6db02a..4a39c9d50489 100644 --- a/tools/testing/vma/shared.c +++ b/tools/testing/vma/shared.c @@ -23,7 +23,8 @@ struct vm_area_struct *alloc_vma(struct mm_struct *mm, =20 vma->vm_start =3D start; vma->vm_end =3D end; - vma->vm_pgoff =3D pgoff; + vma_set_pgoff(vma, pgoff); + vma_set_anon_pgoff(vma, start >> PAGE_SHIFT); vma->flags =3D vma_flags; vma_assert_detached(vma); =20 diff --git a/tools/testing/vma/tests/merge.c b/tools/testing/vma/tests/merg= e.c index e357accc8499..48418b82b01d 100644 --- a/tools/testing/vma/tests/merge.c +++ b/tools/testing/vma/tests/merge.c @@ -45,6 +45,7 @@ void vmg_set_range(struct vma_merge_struct *vmg, unsigned= long start, vmg->start =3D start; vmg->end =3D end; vmg->pgoff =3D pgoff; + vmg->anon_pgoff =3D start >> PAGE_SHIFT; vmg->vma_flags =3D vma_flags; =20 vmg->just_expand =3D false; @@ -108,6 +109,7 @@ static bool test_simple_merge(void) .end =3D 0x2000, .vma_flags =3D vma_flags, .pgoff =3D 1, + .anon_pgoff =3D 1, }; =20 ASSERT_FALSE(attach_vma(&mm, vma_left)); @@ -1431,7 +1433,7 @@ static bool test_expand_only_mode(void) struct mm_struct mm =3D {}; VMA_ITERATOR(vmi, &mm, 0); struct vm_area_struct *vma_prev, *vma; - VMG_STATE(vmg, &mm, &vmi, 0x5000, 0x9000, vma_flags, 5); + VMG_STATE(vmg, &mm, &vmi, 0x5000, 0x9000, vma_flags, 5, 5); =20 /* * Place a VMA prior to the one we're expanding so we assert that we do diff --git a/tools/testing/vma/tests/vma.c b/tools/testing/vma/tests/vma.c index 0d40d7ba2181..c8ef7b8cd46b 100644 --- a/tools/testing/vma/tests/vma.c +++ b/tools/testing/vma/tests/vma.c @@ -40,7 +40,7 @@ static bool test_copy_vma(void) vma =3D alloc_and_link_vma(&mm, 0x1000, 0x2000, 1, vma_flags); vma_set_anonymous(vma); vma_orig =3D vma; - vma_new =3D copy_vma(&vma, 0x2000, 0x1000, 1, &need_locks); + vma_new =3D copy_vma(&vma, 0x2000, 0x1000, 1, 1, &need_locks); ASSERT_EQ(vma_new, vma_orig); ASSERT_EQ(vma, vma_orig); ASSERT_EQ(vma_new->vm_start, 0x1000); @@ -53,7 +53,7 @@ static bool test_copy_vma(void) vma =3D alloc_and_link_vma(&mm, 0x2000, 0x3000, 2, vma_flags); vma_set_anonymous(vma); vma_orig =3D vma; - vma_new =3D copy_vma(&vma, 0x1000, 0x1000, 2, &need_locks); + vma_new =3D copy_vma(&vma, 0x1000, 0x1000, 2, 2, &need_locks); ASSERT_EQ(vma_new, vma_orig); ASSERT_EQ(vma, vma_orig); ASSERT_EQ(vma_new->vm_start, 0x1000); @@ -71,7 +71,7 @@ static bool test_copy_vma(void) vma =3D alloc_and_link_vma(&mm, 0x3000, 0x4000, 3, vma_flags); vma_set_anonymous(vma); vma_orig =3D vma; - vma_new =3D copy_vma(&vma, 0x2000, 0x1000, 3, &need_locks); + vma_new =3D copy_vma(&vma, 0x2000, 0x1000, 3, 3, &need_locks); ASSERT_NE(vma_new, vma_orig); ASSERT_EQ(vma_new, vma); ASSERT_EQ(vma_new->vm_start, 0x1000); @@ -82,7 +82,7 @@ static bool test_copy_vma(void) /* Move backwards and do not merge. */ =20 vma =3D alloc_and_link_vma(&mm, 0x3000, 0x5000, 3, vma_flags); - vma_new =3D copy_vma(&vma, 0, 0x2000, 0, &need_locks); + vma_new =3D copy_vma(&vma, 0, 0x2000, 0, 3, &need_locks); ASSERT_NE(vma_new, vma); ASSERT_EQ(vma_new->vm_start, 0); ASSERT_EQ(vma_new->vm_end, 0x2000); @@ -95,7 +95,7 @@ static bool test_copy_vma(void) =20 vma =3D alloc_and_link_vma(&mm, 0, 0x2000, 0, vma_flags); vma_next =3D alloc_and_link_vma(&mm, 0x6000, 0x8000, 6, vma_flags); - vma_new =3D copy_vma(&vma, 0x4000, 0x2000, 4, &need_locks); 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charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260806-b4-scalable-cow-virt-pgoff-v4-10-ab318a350404@kernel.org> References: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> In-Reply-To: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> To: Andrew Morton , David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Miaohe Lin , Naoya Horiguchi , Rik van Riel , Harry Yoo , Lance Yang , Kees Cook , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Usama Arif , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Peter Xu , Xu Xin , Chengming Zhou , Arnd Bergmann , Greg Kroah-Hartman , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Sven Schnelle , Alex Deucher , =?utf-8?q?Christian_K=C3=B6nig?= , David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Boris Brezillon , Steven Price , Liviu Dudau , Huang Rui , Matthew Auld , =?utf-8?q?Thomas_Hellstr=C3=B6m?= , Rodrigo Vivi , Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Jason Gunthorpe , John Hubbard , Muchun Song , Oscar Salvador , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Youngjun Park Cc: "Lorenzo Stoakes (ARM)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, intel-xe@lists.freedesktop.org, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=2286; i=ljs@kernel.org; h=from:subject:message-id; bh=gUsQ8Jm4b1wdTqyWtNbp+uv3FdHISPYvdCAHWw1Td6A=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLJK3lzYqhX/vp1DaYfVrK8yHf8mRQl15L+UXOP1faHKs tIp88y+dJSyMIhxMciKKbI8/yK+P0gkbF7nBX83mDmsTCBDGLg4BWAi2jMYGXY+7NBwvuTCv77V Oc5PO9T8ivKlrYIXOWrLf8XVRBX1LGL4H7jIvHfq8//zGvLsjxw7yWO050nNpzOy0qKHWLNnvZi byQ0A X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 Update the page_vma_mapped_walk structure to track whether the pgoff being tracked is an anonymous pgoff or not and update the comments to reflect this. This is necessary in order to determine the correct VMA page offset in vma_address_end() when pvmw->nr_pages > 1. Also document that pvmw->pgoff is meaningless for pvmw->nr_pages =3D=3D 1 a= nd for KSM. Do not set this field where pgoff is not specified. This is laying the groundwork for eventually using anonymous page offsets as the index for all anonymous folios. No functional change intended. Signed-off-by: Lorenzo Stoakes (ARM) Acked-by: David Hildenbrand (Arm) --- include/linux/rmap.h | 4 +++- mm/rmap.c | 2 ++ 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 8dc0871e5f00..0574537a355c 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -864,13 +864,14 @@ struct page *make_device_exclusive(struct mm_struct *= mm, unsigned long addr, struct page_vma_mapped_walk { unsigned long pfn; unsigned long nr_pages; - pgoff_t pgoff; + pgoff_t pgoff; /* Only meaningful if nr_pages > 1 and not a KSM walk */ struct vm_area_struct *vma; unsigned long address; pmd_t *pmd; pte_t *pte; spinlock_t *ptl; unsigned int flags; + bool pgoff_is_anon : 1; }; =20 #define DEFINE_FOLIO_VMA_WALK(name, _folio, _vma, _address, _flags) \ @@ -881,6 +882,7 @@ struct page_vma_mapped_walk { .vma =3D _vma, \ .address =3D _address, \ .flags =3D _flags, \ + .pgoff_is_anon =3D folio_test_anon(_folio), \ } =20 static inline void page_vma_mapped_walk_done(struct page_vma_mapped_walk *= pvmw) diff --git a/mm/rmap.c b/mm/rmap.c index 5798427d007f..ab3f879454de 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1240,6 +1240,7 @@ static bool mapping_wrprotect_range_one(struct folio = *folio, .vma =3D vma, .address =3D address, .flags =3D PVMW_SYNC, + .pgoff_is_anon =3D false, }; =20 state->cleaned +=3D page_vma_mkclean_one(&pvmw); @@ -1317,6 +1318,7 @@ int pfn_mkclean_range(unsigned long pfn, unsigned lon= g nr_pages, pgoff_t pgoff, .pgoff =3D pgoff, .vma =3D vma, .flags =3D PVMW_SYNC, + .pgoff_is_anon =3D false, }; =20 if (invalid_mkclean_vma(vma, NULL)) --=20 2.55.0 From nobody Wed Sep 30 20:13:06 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A06E23ED135; Thu, 6 Aug 2026 20:25:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786047961; cv=none; b=uj4CG/IrsPRpHYzvHbv8y63rLB+OuKOKRzLDMX6dViwnD7dkKsM8mKkAT/RFQr7YhwOBKcK+498odKyadRAPCQInRG9zYyBu5+qTUkkYKvCnHCRuEOMfJZ1/WgzdZLUqZTic1IbuIkIPaPWpvVJMGYgEuvtBp4tYIjXsQzGdm7Q= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786047961; c=relaxed/simple; bh=p3P1FLjNmsKquOfKyZ9JRZehrfWrVy9CMy59xXBf5Js=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=W+CkgvcBQUUh4KVf0K7n7jjlpKFyggnta2L+SVzPTBnn+LBNaNt0j6Rsw5RD5f+RVI81sIcY/vP/7drPkEv+nZkuzKfmI65xhgraSxCBges5e1n8btgWo7wJfVs+u/EM2hhPPqSF3qabL+dSUZ+ZK1DWTm3Ejs9CQytdk/tfsV4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=XLaBEEfi; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="XLaBEEfi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A10771F00A3D; Thu, 6 Aug 2026 20:25:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786047958; bh=9aEc+GpTkQ0+PyuSQU7RLIhs+vRcJAzmQsvl5QanIRU=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=XLaBEEfisdymhdMAkrk6t/WHMuk76cQnpPqVJx/MdqUpfsyAOq8O9FcCUK5GppgIp w7FnNc6qQQ0UNCMPFsuI6Jax1IE0OYNlqFucf6RWEoE2XlOgVc4Rk3vK5+CSDdUmY8 p44YMxs/hfqSJ1P1IdejNuBo1hKTQF2e8eNGUSsxRik61Rl6PY8NtTMk8b3JbCFjKp m5QGQy3/se94DfwMWTn7kQEjqaguvLEJoU8xj1Q/GGWvwP5FJuQZCK96QJNd1NVz/R D8qLVd0suYrx9nGQDf1i8x/ZxFpE+E1WIcwD3tJYm9/xVPBEWRE1uUcx2IsGZD9/k2 SVtiXx///mnLw== From: "Lorenzo Stoakes (ARM)" Date: Thu, 06 Aug 2026 21:21:36 +0100 Subject: [PATCH v4 11/20] mm: clean up vma_address_end() Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260806-b4-scalable-cow-virt-pgoff-v4-11-ab318a350404@kernel.org> References: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> In-Reply-To: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> To: Andrew Morton , David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Miaohe Lin , Naoya Horiguchi , Rik van Riel , Harry Yoo , Lance Yang , Kees Cook , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Usama Arif , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Peter Xu , Xu Xin , Chengming Zhou , Arnd Bergmann , Greg Kroah-Hartman , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Sven Schnelle , Alex Deucher , =?utf-8?q?Christian_K=C3=B6nig?= , David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Boris Brezillon , Steven Price , Liviu Dudau , Huang Rui , Matthew Auld , =?utf-8?q?Thomas_Hellstr=C3=B6m?= , Rodrigo Vivi , Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Jason Gunthorpe , John Hubbard , Muchun Song , Oscar Salvador , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Youngjun Park Cc: "Lorenzo Stoakes (ARM)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, intel-xe@lists.freedesktop.org, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=1986; i=ljs@kernel.org; h=from:subject:message-id; bh=p3P1FLjNmsKquOfKyZ9JRZehrfWrVy9CMy59xXBf5Js=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLJK3lz4rtf2q3xF3rGaAu1zfh9Zdudted1+r7vBoOHDr 6uNy3O3d5SyMIhxMciKKbI8/yK+P0gkbF7nBX83mDmsTCBDGLg4BWAiTFMZ/mc+EX+ZtKmTb31U z6fvdm+/6MbrG2Xmsr7RP2Yf8Krx4mWG/66pky2Xek6cYnxu+bc7N/frhYs8qT6pY3HlUo7Wbpb dVowA X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 vma_address_end() is a confusing function with a lot of moving parts so clean it up prior to extending it for anon page indexed mappings. Const-ify some variables and establish pgoff_vma_start and pgoff_end variables to clearly identify the page offset for the start of the VMA and the end of the page offset range specified by the page walk. This simplifies the function significantly and lays the groundwork for a future change to update this function to account for anonymously page indexed folios. No functional change intended. Signed-off-by: Lorenzo Stoakes (ARM) Acked-by: David Hildenbrand (Arm) --- mm/internal.h | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/mm/internal.h b/mm/internal.h index 03145b8d0d56..98b067472ceb 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -1079,22 +1079,24 @@ static inline unsigned long vma_anon_address(const = struct vm_area_struct *vma, } =20 /* - * Then at what user virtual address will none of the range be found in vm= a? + * At what user virtual address will none of the range be found in vma? * Assumes that vma_address() already returned a good starting address. */ static inline unsigned long vma_address_end(struct page_vma_mapped_walk *p= vmw) { - struct vm_area_struct *vma =3D pvmw->vma; - pgoff_t pgoff; + const pgoff_t pgoff_end =3D pvmw->pgoff + pvmw->nr_pages; + const struct vm_area_struct *vma =3D pvmw->vma; + pgoff_t pgoff_vma_start; unsigned long address; =20 /* Common case, plus ->pgoff is invalid for KSM */ if (pvmw->nr_pages =3D=3D 1) return pvmw->address + PAGE_SIZE; =20 - pgoff =3D pvmw->pgoff + pvmw->nr_pages; + pgoff_vma_start =3D vma_start_pgoff(vma); + address =3D vma->vm_start + - ((pgoff - vma_start_pgoff(vma)) << PAGE_SHIFT); + ((pgoff_end - pgoff_vma_start) << PAGE_SHIFT); /* Check for address beyond vma (or wrapped through 0?) */ if (address < vma->vm_start || address > vma->vm_end) address =3D vma->vm_end; --=20 2.55.0 From nobody Wed Sep 30 20:13:06 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D36563750AC; Thu, 6 Aug 2026 20:26:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786047981; cv=none; b=SdRPoRTXj6JM5vcbGW3HP3Df4fXVYWq4DNUst5dtYrq2yKwDKpJML7MZz1lNKKzCut5hb/ZxOCpDrYWXCGgW7EmXRrZDsYtnhQmUj+p4L7eVNSBPfNK9aB+jHqlqOsLtRZkn3Neev+wglbKe+sZUSheeI+5jRGLzteMwwrEP294= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786047981; c=relaxed/simple; bh=FQvfrIChtfCHHXCKi2iMmw+WlLObO/vvN/oq4qWGhM0=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=IJ9i7NMuYwjPwV9rXCvXisPVHsNbWNymwgQvKWzHzSQ+b8z1bt3/FFVbjzfc96u6mp0LHN1eZoFKS2BqKuzl1PGNpxj7sq6nphUNVXiRWypY9WpkbotUeoORVerfcdWQHKWlr+DADjAaZwEgup/VB/Oji+mIdxt5AYE/bqYP3tY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=lDrqZrNR; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="lDrqZrNR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 52F6A1F000E9; Thu, 6 Aug 2026 20:25:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786047979; bh=Yu2gHLRO/SRcmXO93obChsLu5SUfHnH/15hgrAMzxms=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=lDrqZrNR/iyUmRO+7Z821lHEcT77036v+dj9GNHtUzgqrvxHacNZrqPcieg2kFf43 5HGbiuVs1H2Ve7zRIBdILvDZkIrcpocaVff5jnMAZzWLZg2YNb+Z9a82hwrlqDC179 2FNHNc8gt0ohZFRtnB8QeJLOtoCkiKBc8gkwVGHzQUQa7gedN8WTtjcgwQIMcY7nkb LqD9qwm5KLRniYu3UF9X2g/XBoYniq5+YbWe49I4clFRHPT238KYlH8gr9XZ+5iekV 3lwQaZKSn1TWM+iyon8etePZojIgXmHbpASvl5XH+XGN2VM6Q28c+jxiu8cqLD8JVS na0KUcOWeR8eA== From: "Lorenzo Stoakes (ARM)" Date: Thu, 06 Aug 2026 21:21:37 +0100 Subject: [PATCH v4 12/20] mm/huge_memory: update remove_migration_pmd() to accept a folio Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260806-b4-scalable-cow-virt-pgoff-v4-12-ab318a350404@kernel.org> References: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> In-Reply-To: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> To: Andrew Morton , David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Miaohe Lin , Naoya Horiguchi , Rik van Riel , Harry Yoo , Lance Yang , Kees Cook , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Usama Arif , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Peter Xu , Xu Xin , Chengming Zhou , Arnd Bergmann , Greg Kroah-Hartman , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Sven Schnelle , Alex Deucher , =?utf-8?q?Christian_K=C3=B6nig?= , David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Boris Brezillon , Steven Price , Liviu Dudau , Huang Rui , Matthew Auld , =?utf-8?q?Thomas_Hellstr=C3=B6m?= , Rodrigo Vivi , Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Jason Gunthorpe , John Hubbard , Muchun Song , Oscar Salvador , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Youngjun Park Cc: "Lorenzo Stoakes (ARM)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, intel-xe@lists.freedesktop.org, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=3764; i=ljs@kernel.org; h=from:subject:message-id; bh=FQvfrIChtfCHHXCKi2iMmw+WlLObO/vvN/oq4qWGhM0=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLJK3lwoPfTn83L/Ct6FU6LefJ/nERIndmuDX9Mxs9Upq jzvj/3l6ShlYRDjYpAVU2R5/kV8f5BI2LzOC/5uMHNYmUCGMHBxCsBEHiszMnRONebz33Tm321v 5aounvlauhNrJ3470nLLuK9hVaDcwypGhiPhRnsvn8m5/+K71JUYLtsNzQz8axce+Swm1FR37hj rDUYA X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 This function does not need to accept a page and requiring it to is unneces= sary and misleading. make_[writable, readable]_device_private_entry() must be passed a PMD-aligned PFN as they immediately used to obtain a softleaf PMD entry and the same argument applies to folio_add_[anon, file]_rmap_pmd(). While we are here, update a VM_BUG_ON() to a VM_WARN_ON_ONCE(). No functional change intended. Signed-off-by: Lorenzo Stoakes (ARM) Acked-by: David Hildenbrand (Arm) --- include/linux/swapops.h | 6 +++--- mm/huge_memory.c | 16 +++++++--------- mm/migrate.c | 2 +- 3 files changed, 11 insertions(+), 13 deletions(-) diff --git a/include/linux/swapops.h b/include/linux/swapops.h index c956bc445ee0..1f3ff3b93e16 100644 --- a/include/linux/swapops.h +++ b/include/linux/swapops.h @@ -325,8 +325,8 @@ struct page_vma_mapped_walk; extern int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, struct page *page); =20 -extern void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, - struct page *new); +void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, + struct folio *folio); =20 extern void pmd_migration_entry_wait(struct mm_struct *mm, pmd_t *pmd); =20 @@ -346,7 +346,7 @@ static inline int set_pmd_migration_entry(struct page_v= ma_mapped_walk *pvmw, } =20 static inline void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, - struct page *new) + struct folio *folio) { BUILD_BUG(); } diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 6b0cabd45b2d..47c9c6e32eba 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -5020,9 +5020,8 @@ int set_pmd_migration_entry(struct page_vma_mapped_wa= lk *pvmw, return 0; } =20 -void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *= new) +void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct folio = *folio) { - struct folio *folio =3D page_folio(new); struct vm_area_struct *vma =3D pvmw->vma; struct mm_struct *mm =3D vma->vm_mm; unsigned long address =3D pvmw->address; @@ -5058,11 +5057,9 @@ void remove_migration_pmd(struct page_vma_mapped_wal= k *pvmw, struct page *new) swp_entry_t entry; =20 if (pmd_write(pmde)) - entry =3D make_writable_device_private_entry( - page_to_pfn(new)); + entry =3D make_writable_device_private_entry(folio_pfn(folio)); else - entry =3D make_readable_device_private_entry( - page_to_pfn(new)); + entry =3D make_readable_device_private_entry(folio_pfn(folio)); pmde =3D softleaf_to_pmd(entry); =20 if (pmd_swp_soft_dirty(*pvmw->pmd)) @@ -5077,11 +5074,12 @@ void remove_migration_pmd(struct page_vma_mapped_wa= lk *pvmw, struct page *new) if (!softleaf_is_migration_read(entry)) rmap_flags |=3D RMAP_EXCLUSIVE; =20 - folio_add_anon_rmap_pmd(folio, new, vma, haddr, rmap_flags); + folio_add_anon_rmap_pmd(folio, &folio->page, vma, haddr, rmap_flags); } else { - folio_add_file_rmap_pmd(folio, new, vma); + folio_add_file_rmap_pmd(folio, &folio->page, vma); } - VM_BUG_ON(pmd_write(pmde) && folio_test_anon(folio) && !PageAnonExclusive= (new)); + VM_WARN_ON_ONCE(pmd_write(pmde) && folio_test_anon(folio) && + !PageAnonExclusive(&folio->page)); set_pmd_at(mm, haddr, pvmw->pmd, pmde); =20 /* No need to invalidate - it was non-present before */ diff --git a/mm/migrate.c b/mm/migrate.c index 222c8c15f782..d08eff028483 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -372,7 +372,7 @@ static bool remove_migration_pte(struct folio *folio, if (!pvmw.pte) { VM_BUG_ON_FOLIO(folio_test_hugetlb(folio) || !folio_test_pmd_mappable(folio), folio); - remove_migration_pmd(&pvmw, new); + remove_migration_pmd(&pvmw, folio); continue; } #endif --=20 2.55.0 From nobody Wed Sep 30 20:13:06 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 547E2490C03; Thu, 6 Aug 2026 20:26:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786048005; cv=none; b=UgIeiPUtOOT1rIqQZka8CRPWiiXQBhBUfCPhxwPevxZQ+308x1oNtOFX71vHnE7mrxMlJKQ7vuD4YSw3kmqWjKmp8OS44WGa1z2QC4YFE0xUjjbYAAwh6IO0JFaaa4pyFdiIPJP22SWK0XIwv9Jl9bfxeq/nowJlotJLA2hxOuc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786048005; c=relaxed/simple; bh=VU6CEEOG+lJfZQJv2x390tNJn50dr5hRnWobWlENiyQ=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=bfRW/VHy2yemrROcMyqqhOj6OdQbWaYtm0dW/RQ6GKLL5SjHc5apF+tuO7OgISo4Ls6yg1xKw8+R//x8dJuxx+0gc6G783QuUZGBR2lkV2X8NV75q3bto06xoUOLvjQ9WyeCVksq65SbtSnngE9JoZ7q4bUbWmaog7t8HKdAPfg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Bz9YaJqm; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Bz9YaJqm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 07A611F00A3A; Thu, 6 Aug 2026 20:26:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786048000; bh=mn4YT2ApRSaopzXET2AIgz+wXZFI9xEUztyKfd8FJpo=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=Bz9YaJqmzlxB4WCv5/P0brr34RZLbO+nw7RKtFIuMtIXr1B23WLcGGfVbZws5JHDg 4W0kn5/MYFl5uOyKgkWovKIR5IoBwr9+SKhfM4P4019fElq3qbQSO5N9RxlRdB98Zd dFccbeEQZ6D3yiweV2Uk8FBxCT7ingqNrMod9zl/Jd4+1vzyRBOi6ZHeHk/cEpObjG cjTcZh6aV81dh3W646BTZoW3aNzM/uyXFcS428mV4apxTQH9uqQzr+8f6uBW3GpiPr jkMDDx0NKuEkOo4Dr5IZx1YkmcvM9F7uFFuv7qetTFV0tBN0/Z0si4F93VwSRYe9lM V2dwQkk8HKt8g== From: "Lorenzo Stoakes (ARM)" Date: Thu, 06 Aug 2026 21:21:38 +0100 Subject: [PATCH v4 13/20] mm/migrate: calculate large folio page index using PFN Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260806-b4-scalable-cow-virt-pgoff-v4-13-ab318a350404@kernel.org> References: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> In-Reply-To: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> To: Andrew Morton , David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Miaohe Lin , Naoya Horiguchi , Rik van Riel , Harry Yoo , Lance Yang , Kees Cook , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Usama Arif , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Peter Xu , Xu Xin , Chengming Zhou , Arnd Bergmann , Greg Kroah-Hartman , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Sven Schnelle , Alex Deucher , =?utf-8?q?Christian_K=C3=B6nig?= , David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Boris Brezillon , Steven Price , Liviu Dudau , Huang Rui , Matthew Auld , =?utf-8?q?Thomas_Hellstr=C3=B6m?= , Rodrigo Vivi , Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Jason Gunthorpe , John Hubbard , Muchun Song , Oscar Salvador , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Youngjun Park Cc: "Lorenzo Stoakes (ARM)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, intel-xe@lists.freedesktop.org, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=2203; i=ljs@kernel.org; h=from:subject:message-id; bh=VU6CEEOG+lJfZQJv2x390tNJn50dr5hRnWobWlENiyQ=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLJK3lwIeJB2srlfIsx5i0XEmznfF7X3dO30t4+XfDqPh WeebItfRykLgxgXg6yYIsvzL+L7g0TC5nVe8HeDmcPKBDKEgYtTACbyj5GR4cmCVwrPdJPy3rfs 3eN89PEFz+UFG88c4vOcMONUrdiM7BhGhnmzX6asljjyXeCF29OA97E6XqnzKu54/Lqf8L9X/c2 fEDYA X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 Rather than having to figure out the page index to use using linear_page_index(), calculate it using PFN. This is a more natural fit as the linear page index is immaterial to determining the folio page index. Derive the page index from the offset between migration entry PFN and folio PFN - pvmw.pfn (set via DEFINE_FOLIO_VMA_WALK() which uses folio_pfn() to obtain it). Additionally remove a not so useful comment and clean the code layout up. No functional change intended. Suggested-by: David Hildenbrand (Arm) Signed-off-by: Lorenzo Stoakes (ARM) Acked-by: David Hildenbrand (Arm) --- mm/migrate.c | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) diff --git a/mm/migrate.c b/mm/migrate.c index d08eff028483..50d0b547bca3 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -356,16 +356,11 @@ static bool remove_migration_pte(struct folio *folio, =20 while (page_vma_mapped_walk(&pvmw)) { rmap_t rmap_flags =3D RMAP_NONE; - pte_t old_pte; - pte_t pte; + unsigned long idx =3D 0; softleaf_t entry; struct page *new; - unsigned long idx =3D 0; - - /* pgoff is invalid for ksm pages, but they are never large */ - if (folio_test_large(folio) && !folio_test_hugetlb(folio)) - idx =3D linear_page_index(vma, pvmw.address) - pvmw.pgoff; - new =3D folio_page(folio, idx); + pte_t old_pte; + pte_t pte; =20 #ifdef CONFIG_ARCH_HAS_PMD_SOFTLEAVES /* PMD-mapped THP migration entry */ @@ -381,14 +376,18 @@ static bool remove_migration_pte(struct folio *folio, pvmw.pte); else old_pte =3D ptep_get(pvmw.pte); + + entry =3D softleaf_from_pte(old_pte); + if (folio_test_large(folio) && !folio_test_hugetlb(folio)) + idx =3D softleaf_to_pfn(entry) - pvmw.pfn; + if (rmap_walk_arg->map_unused_to_zeropage && try_to_map_unused_to_zeropage(&pvmw, folio, old_pte, idx)) continue; =20 folio_get(folio); + new =3D folio_page(folio, idx); pte =3D mk_pte(new, READ_ONCE(vma->vm_page_prot)); - - entry =3D softleaf_from_pte(old_pte); if (!softleaf_is_migration_young(entry)) pte =3D pte_mkold(pte); if (folio_test_dirty(folio) && softleaf_is_migration_dirty(entry)) --=20 2.55.0 From nobody Wed Sep 30 20:13:06 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C55E73D4123; Thu, 6 Aug 2026 20:27:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786048023; cv=none; b=A2kzhnM5UecqESRtGWRLH3Pwce5XxKylk9BeCZ5SUi3RMz9U1Kj0LUo1ifn/ajLVvoSFCjrwSg77dtZlANEEB9ygI+/3SdLojt3Lo6U+SJRiFithNvvoNlsTYWDrrDTiSsd6opuxlPeB7WyBE9uJj3tYSNdv7vxNPvGLVOPz67o= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786048023; c=relaxed/simple; bh=cq+w9cKznEkUFFIRK+kQBV3eJCOH+aefQvQeEweMN2E=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=PdYCYUT6dHAjK/UiLuIrX+cpskYdntfwbCrU7jydehgXy3+FNluUIqTws6ztUHzZ5Mb+nu6IxeRYmZaGTVSWZ5Ea3vJN+Io7IEOJiSyOYQlfjCBcR5FnTA0jdOKZsvoSUO6ne7q6Q7SFHaYZKyNOreg0ztqj1CKdHIoawvb+80k= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=A+tcfoQ7; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="A+tcfoQ7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B0F1F1F000E9; Thu, 6 Aug 2026 20:26:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786048020; bh=LEh+PvHZuK7zS28iAxANz8rkRX1gjZT6GNHr1SQ0KwA=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=A+tcfoQ7F+D1rCSH27lhfC59/fNUWrJv1iZWVRUn8PJTuyVoFIQdom1rZSaJqIyEg 7W2j8wJdXNCKeo1bHAAd7r9fFiHLge1KyXJiZt+dYcq4V9w+dU80Rn4GXXBtHUQ48U umDFzKNajoWQWELYOlDstCgThlt5uR4ZdBtiErlmLsoAbQ3U/u7qMvbaJ5RD3puccn cOHifSbkMiaV1MQM/bGQlsuGZ5AusT2CiMfm19bNFqlCC4yfH4yMc/5F8V7eHdTdnl NtKxwDW+Zqx93mIq3GdhmWx6EsqrYWgWiqs6vgaRR1DHzvTVxamOxV8nXFOUF59gFb k+169t+0qW66Q== From: "Lorenzo Stoakes (ARM)" Date: Thu, 06 Aug 2026 21:21:39 +0100 Subject: [PATCH v4 14/20] mm/rmap: use anon pgoff to track MAP_PRIVATE file-backed anon folios Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260806-b4-scalable-cow-virt-pgoff-v4-14-ab318a350404@kernel.org> References: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> In-Reply-To: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> To: Andrew Morton , David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Miaohe Lin , Naoya Horiguchi , Rik van Riel , Harry Yoo , Lance Yang , Kees Cook , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Usama Arif , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Peter Xu , Xu Xin , Chengming Zhou , Arnd Bergmann , Greg Kroah-Hartman , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Sven Schnelle , Alex Deucher , =?utf-8?q?Christian_K=C3=B6nig?= , David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Boris Brezillon , Steven Price , Liviu Dudau , Huang Rui , Matthew Auld , =?utf-8?q?Thomas_Hellstr=C3=B6m?= , Rodrigo Vivi , Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Jason Gunthorpe , John Hubbard , Muchun Song , Oscar Salvador , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Youngjun Park Cc: "Lorenzo Stoakes (ARM)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, intel-xe@lists.freedesktop.org, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=14081; i=ljs@kernel.org; h=from:subject:message-id; bh=cq+w9cKznEkUFFIRK+kQBV3eJCOH+aefQvQeEweMN2E=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLJK3lwo3dypGXQweFOHyZpPMcaNmtlt69d+nWV4Z25e6 fdNok9mdpSyMIhxMciKKbI8/yK+P0gkbF7nBX83mDmsTCBDGLg4BWAizCsY/teUXjtfdMu0n+PQ 1I+7fyqnbHwrwvLyx9UXfxqnzF0vumk6w3+/36ty79lOmmfJEXlY2mXvuapDftPytY8ZxXDP53j 6eAYfAA== X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 Currently anonymous folios belonging to CoW'd MAP_PRIVATE file-backed mappings are indexed by their page offset within the file in which they were originally mapped. This differs from anonymous folios belonging to pure anon mappings which are indexed by their anonymous page offset (the address at which they'd belong in the VMA when first faulted). This change fixes this inconsistency, always indexing anonymous folios by their anonymous page offset regardless of the VMA to which they belong. The foundations have been laid such that we need only switch this functionality on such by: * Using linear_anon_page_index() in __folio_set_anon() to assign the folio's index to the anonymous linear index rather than the file-backed one. * Otherwise using linear_anon_page_index() in all instances where anonymous folios are being referenced or manipulated. * Replacing vma_address() with vma_filebacked_address() or vma_anon_address() as appropriate. * Updating the merging logic to check that anonymous page offsets are aligned as well as filebacked ones for MAP_PRIVATE file-backed VMAs, introducing needs_adjacent_anon_pgoff() to figure out when this is required. * Updating linear_folio_page_index() to invoke linear_anon_page_index() if the folio is anonymous. * Updating vma_address_end() to use the VMA's anonymous page offset when pvmw->pgoff is anonymous. * Correcting folio_within_range() to use anonymous page offset for anonymous folios. This will have no impact on merging of anonymous VMAs, whose page offset and anonymous page offset are identical, nor will it impact shared file-backed VMAs, which will continue to be merged based on the file-backed page offset. However, MAP_PRIVATE file-backed mappings must now be aligned on anonymous page offset as well. In most instances this should have no impact on merging of file-backed mappings, which are usually not merged all that often, let alone MAP_PRIVATE mapped ones, and rarely remapped and faulted before being moved back in place (the case in which a merge may now fail). One subtle impact of this change is in NUMA interleaving - since commit 88c91dc58582 ("mempolicy: migration attempt to match interleave nodes"), migration heuristically tries to maintain interleaving behaviour matching the policy using folio indices. When doing migration of CoW'd MAP_PRIVATE-file backed ranges, the 'base' upon which the interleaving behaviour is performed will vary for these ranges. However the commit notes that ranges spanning multiple VMAs will already cause varying bases, and that this is an acceptable approximation. It is very unlikely real world use-cases will be impacted by this (MAP_PRIVATE file-backed mappings are already an edge case), and all that will happen is that such ranges will cause interleaving to be rotated over the CoW'd range, with little to no impact. This commit lays the foundations for future scalable CoW work which needs to track some remaps, meaning that most remap tracking can be avoided, and in nearly all cases the anonymous page offset will be able to be used to quickly find the VMA in an mm. Note that the need_rmap_locks check doesn't need to be updated, as any remapping will offset both the anonymous and file-backed page offset, so it suffices to check only one. Signed-off-by: Lorenzo Stoakes (ARM) Acked-by: David Hildenbrand (Arm) --- mm/huge_memory.c | 2 +- mm/internal.h | 27 ++++++++------------------- mm/interval_tree.c | 4 ++-- mm/ksm.c | 6 +++--- mm/page_vma_mapped.c | 2 +- mm/rmap.c | 12 ++++++------ mm/userfaultfd.c | 4 ++-- mm/vma.c | 32 +++++++++++++++++++++++++++++++- 8 files changed, 54 insertions(+), 35 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 47c9c6e32eba..e46b3a4750ee 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2887,7 +2887,7 @@ int move_pages_huge_pmd(struct mm_struct *mm, pmd_t *= dst_pmd, pmd_t *src_pmd, pm } =20 folio_move_anon_rmap(src_folio, dst_vma); - src_folio->index =3D linear_page_index(dst_vma, dst_addr); + src_folio->index =3D linear_anon_page_index(dst_vma, dst_addr); =20 _dst_pmd =3D folio_mk_pmd(src_folio, dst_vma->vm_page_prot); /* Follow mremap() behavior and treat the entry dirty after the move */ diff --git a/mm/internal.h b/mm/internal.h index 98b067472ceb..5892b7453b54 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -933,7 +933,8 @@ folio_within_range(struct folio *folio, struct vm_area_= struct *vma, return false; =20 pgoff_folio =3D folio_pgoff(folio); - pgoff_vma_start =3D vma_start_pgoff(vma); + pgoff_vma_start =3D folio_test_anon(folio) ? + vma_start_anon_pgoff(vma) : vma_start_pgoff(vma); =20 if (start < vma->vm_start) start =3D vma->vm_start; @@ -1044,23 +1045,8 @@ static inline unsigned long vma_filebacked_address(c= onst struct vm_area_struct * } =20 /** - * vma_address - Find the virtual address a page range is mapped at. - * @vma: The vma which maps this object. - * @pgoff: The page offset within its object. - * @nr_pages: The number of pages to consider. - * - * If any page in this range is mapped by this VMA, return the first addre= ss - * where any of these pages appear. Otherwise, return -EFAULT. - */ -static inline unsigned long vma_address(const struct vm_area_struct *vma, - pgoff_t pgoff, unsigned long nr_pages) -{ - return __vma_address(vma, pgoff, vma_start_pgoff(vma), nr_pages); -} - -/** - * vma_anon_address - Find the address an anonymous folio with index @pgof= f_anon - * is mapped at. + * vma_anon_address - Find the virtual address an anonymous page range is = mapped + * at. * @vma: The vma which maps this object. * @pgoff_anon: The anonymous page index belonging to the folio. * @nr_pages: The number of pages to consider. @@ -1093,7 +1079,10 @@ static inline unsigned long vma_address_end(struct p= age_vma_mapped_walk *pvmw) if (pvmw->nr_pages =3D=3D 1) return pvmw->address + PAGE_SIZE; =20 - pgoff_vma_start =3D vma_start_pgoff(vma); + if (pvmw->pgoff_is_anon) + pgoff_vma_start =3D vma_start_anon_pgoff(vma); + else + pgoff_vma_start =3D vma_start_pgoff(vma); =20 address =3D vma->vm_start + ((pgoff_end - pgoff_vma_start) << PAGE_SHIFT); diff --git a/mm/interval_tree.c b/mm/interval_tree.c index 3ae9e106d3af..7bbbf15cfbf0 100644 --- a/mm/interval_tree.c +++ b/mm/interval_tree.c @@ -83,12 +83,12 @@ mapping_rmap_tree_iter_next(struct vm_area_struct *vma, =20 static pgoff_t avc_start_pgoff(struct anon_vma_chain *avc) { - return vma_start_pgoff(avc->vma); + return vma_start_anon_pgoff(avc->vma); } =20 static pgoff_t avc_last_pgoff(struct anon_vma_chain *avc) { - return vma_last_pgoff(avc->vma); + return vma_last_anon_pgoff(avc->vma); } =20 INTERVAL_TREE_DEFINE(struct anon_vma_chain, rb, pgoff_t, rb_subtree_last, diff --git a/mm/ksm.c b/mm/ksm.c index 47006f494fcb..99738a213243 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -1625,7 +1625,7 @@ static int try_to_merge_with_ksm_page(struct ksm_rmap= _item *rmap_item, * stable_tree, break_cow() will clean it up. */ rmap_item->anon_vma =3D vma->anon_vma; - rmap_item->linear_page_index =3D linear_page_index(vma, rmap_item->addres= s); + rmap_item->linear_page_index =3D linear_anon_page_index(vma, rmap_item->a= ddress); get_anon_vma(vma->anon_vma); out: mmap_read_unlock(mm); @@ -3152,7 +3152,7 @@ struct folio *ksm_might_need_to_copy(struct folio *fo= lio, return folio; /* no need to copy it */ } else if (!anon_vma) { return folio; /* no need to copy it */ - } else if (folio->index =3D=3D linear_page_index(vma, addr) && + } else if (folio->index =3D=3D linear_anon_page_index(vma, addr) && anon_vma->root =3D=3D vma->anon_vma->root) { return folio; /* still no need to copy it */ } @@ -3222,7 +3222,7 @@ void rmap_walk_ksm(struct folio *folio, struct rmap_w= alk_control *rwc) /* * Currently, KSM folios are always small folios, so it's * sufficient to search for a single page. We can simply use - * the linear_page_index of the original de-duplicate + * the linear_anon_page_index of the original de-duplicate * anonymous page that we remembered in the rmap_item while * de-duplicating. Note that mremap() always de-duplicates KSM * folios: so if there was mremap() in our parent or our child, diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c index 081e483cc7bf..4e964545e5e8 100644 --- a/mm/page_vma_mapped.c +++ b/mm/page_vma_mapped.c @@ -365,7 +365,7 @@ unsigned long page_mapped_in_vma(const struct page *pag= e, }; =20 if (folio_test_anon(folio)) - pvmw.address =3D vma_address(vma, pgoff, 1); + pvmw.address =3D vma_anon_address(vma, pgoff, 1); else pvmw.address =3D vma_filebacked_address(vma, pgoff, 1); if (pvmw.address =3D=3D -EFAULT) diff --git a/mm/rmap.c b/mm/rmap.c index ab3f879454de..2a9ae25ae72d 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -866,7 +866,7 @@ unsigned long page_address_in_vma(const struct folio *f= olio, vma->anon_vma->root !=3D anon_vma->root) return -EFAULT; /* KSM folios don't reach here because of the !anon_vma check */ - return vma_address(vma, page_pgoff(folio, page), 1); + return vma_anon_address(vma, page_pgoff(folio, page), 1); } else if (!vma->vm_file) { return -EFAULT; } else if (vma->vm_file->f_mapping !=3D folio->mapping) { @@ -1485,7 +1485,7 @@ static void __folio_set_anon(struct folio *folio, str= uct vm_area_struct *vma, */ anon_vma =3D (void *) anon_vma + FOLIO_MAPPING_ANON; WRITE_ONCE(folio->mapping, (struct address_space *) anon_vma); - folio->index =3D linear_page_index(vma, address); + folio->index =3D linear_anon_page_index(vma, address); } =20 /** @@ -1512,8 +1512,8 @@ static void __page_check_anon_rmap(const struct folio= *folio, */ VM_BUG_ON_FOLIO(folio_anon_vma(folio)->root !=3D vma->anon_vma->root, folio); - VM_BUG_ON_PAGE(page_pgoff(folio, page) !=3D linear_page_index(vma, addres= s), - page); + VM_BUG_ON_PAGE(page_pgoff(folio, page) !=3D + linear_anon_page_index(vma, address), page); } =20 static __always_inline void __folio_add_anon_rmap(struct folio *folio, @@ -3040,10 +3040,10 @@ static void rmap_walk_anon(struct folio *folio, pgoff_end =3D pgoff_start + folio_nr_pages(folio) - 1; anon_rmap_tree_foreach(avc, anon_vma, pgoff_start, pgoff_end) { struct vm_area_struct *vma =3D avc->vma; - unsigned long address =3D vma_address(vma, pgoff_start, + const unsigned long address =3D vma_anon_address(vma, pgoff_start, folio_nr_pages(folio)); =20 - VM_BUG_ON_VMA(address =3D=3D -EFAULT, vma); + VM_WARN_ON_ONCE_VMA(address =3D=3D -EFAULT, vma); cond_resched(); =20 if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg)) diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 8fd24c8b428e..24a4d92ffa3c 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -1352,7 +1352,7 @@ static long move_present_ptes(struct mm_struct *mm, } =20 folio_move_anon_rmap(src_folio, dst_vma); - src_folio->index =3D linear_page_index(dst_vma, dst_addr); + src_folio->index =3D linear_anon_page_index(dst_vma, dst_addr); =20 orig_dst_pte =3D folio_mk_pte(src_folio, dst_vma->vm_page_prot); /* Set soft dirty bit so userspace can notice the pte was moved */ @@ -1428,7 +1428,7 @@ static int move_swap_pte(struct mm_struct *mm, struct= vm_area_struct *dst_vma, */ if (src_folio) { folio_move_anon_rmap(src_folio, dst_vma); - src_folio->index =3D linear_page_index(dst_vma, dst_addr); + src_folio->index =3D linear_anon_page_index(dst_vma, dst_addr); } else { /* * Check if the swap entry is cached after acquiring the src_pte diff --git a/mm/vma.c b/mm/vma.c index b55015952f0d..117ca94fc907 100644 --- a/mm/vma.c +++ b/mm/vma.c @@ -204,6 +204,25 @@ static void init_multi_vma_prep(struct vma_prepare *vp, vp->skip_vma_uprobe =3D true; } =20 +/* + * Does this merge require that adjacent VMAs must have adjacent anonymous= page + * offsets in addition to having adjacent vma->vm_pgoff? + * + * This is only required for MAP_PRIVATE-file backed mappings as the page = offset + * for pure anonymous VMAs is equal to the anonymous page offset. + * + * Read-only shared mappings (with VMA_SHARED_BIT cleared) are always unfa= ulted + * so automatically have correct anonymous page offset (as it is always up= dated + * on remap). + * + * 'Special' mappings in the sense of VDSO, VVAR etc. have !file but would= in + * any case not be candidates for merge nor be mergeable. + */ +static bool needs_adjacent_anon_pgoff(const struct vma_merge_struct *vmg) +{ + return vmg->file && vma_flags_is_cow_mapping(&vmg->vma_flags); +} + /* * Return true if we can merge this (vma_flags,anon_vma,file,vm_pgoff) * in front of (at a lower virtual address and file offset than) the vma. @@ -225,6 +244,9 @@ static bool can_vma_merge_before(struct vma_merge_struc= t *vmg) return false; if (vmg_end_pgoff(vmg) !=3D vma_start_pgoff(vmg->next)) return false; + if (needs_adjacent_anon_pgoff(vmg) && + vmg_end_anon_pgoff(vmg) !=3D vma_start_anon_pgoff(vmg->next)) + return false; return true; } =20 @@ -245,6 +267,9 @@ static bool can_vma_merge_after(struct vma_merge_struct= *vmg) return false; if (vma_end_pgoff(vmg->prev) !=3D vmg_start_pgoff(vmg)) return false; + if (needs_adjacent_anon_pgoff(vmg) && + vma_end_anon_pgoff(vmg->prev) !=3D vmg_start_anon_pgoff(vmg)) + return false; return true; } =20 @@ -2048,7 +2073,12 @@ static int anon_vma_compatible(struct vm_area_struct= *a, struct vm_area_struct * if (!vma_flags_empty(&diff)) return false; /* Page offset must align. */ - return vma_end_pgoff(a) =3D=3D vma_start_pgoff(b); + if (vma_end_pgoff(a) !=3D vma_start_pgoff(b)) + return false; + /* Only reached from anon path, so either MAP_PRIVATE file or anon. */ + if (vma_end_anon_pgoff(a) !=3D vma_start_anon_pgoff(b)) + return false; + return true; } =20 /* --=20 2.55.0 From nobody Wed Sep 30 20:13:06 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 193333EDAA9; Thu, 6 Aug 2026 20:27:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786048045; cv=none; b=B+0illU+xBINn4wIODRFJJVm55gFVxxt/dOfJMP1sB1TsOLSdimt2WZ8d0jCX8kcmC/WwNNR5xDSlURD8h/GO8fQw3ybIiY7RBj81ThkkrM8C85dPytkB4JDeBnLPhKOm1qM9RYzQbVfRNMlEX/vZjCSyAtbA7T2FJy1B4dTo+s= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786048045; c=relaxed/simple; bh=c33SLNy9lX4ny9o263CYOjSEcyZN/XsrfEsxty/Rydo=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=ibFcLbgtVX56WcTkdiQbzOgBZZXx4rC7LoQ38ENN1I04hTJy+6Gb5g2PAGLWjW0D0MDDq4D3N0ebiPfm2YaZ7gssTkC+Zi8+oZF9j2thdHliCr5ClIU3lF9aN7nJFL7CkpoxRHEE9RDb1cFavH/QCns0YSrone9aJWwc+hq9qPs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=m+NNPTrX; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="m+NNPTrX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 657591F00A3A; Thu, 6 Aug 2026 20:27:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786048041; bh=+bmGJTDMCDGgU+ycP59x9eyJfos8oUKgJbHiuHs5iEI=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=m+NNPTrXYV52ReXRkAkJozqce/ofgqcNXdiFJ8bf48VWT9fWmbSj9mdrbvFVP6Mze 5V4Gpm8uw8qyu1vqdUoh0pqUlwkCYlo7h88Zz74GtD/A0Mg5wRUxBGZRl0Dxfq0HOF /9ZjhJ1c8UvJByiCHmE/SlyOOHOitRJB7vShFdFMCLwJXS05j/eYt+DYrQrCTc9eER v22ADi/+dhLp+wXva607kppybfenVTPyUghTXdugnksaSSP+/Q9ovmL+1dCzyBn1q4 Hraql7+IYYKMqdzL0IOdetrr5PzScbfe5fZi2734HgMBOQ1ZIJTDrBGSygndbprsNv amv6VeCRpMPrQ== From: "Lorenzo Stoakes (ARM)" Date: Thu, 06 Aug 2026 21:21:40 +0100 Subject: [PATCH v4 15/20] tools/testing/vma: expand VMA merge tests to assert anon pgoff Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260806-b4-scalable-cow-virt-pgoff-v4-15-ab318a350404@kernel.org> References: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> In-Reply-To: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> To: Andrew Morton , David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Miaohe Lin , Naoya Horiguchi , Rik van Riel , Harry Yoo , Lance Yang , Kees Cook , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Usama Arif , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Peter Xu , Xu Xin , Chengming Zhou , Arnd Bergmann , Greg Kroah-Hartman , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Sven Schnelle , Alex Deucher , =?utf-8?q?Christian_K=C3=B6nig?= , David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Boris Brezillon , Steven Price , Liviu Dudau , Huang Rui , Matthew Auld , =?utf-8?q?Thomas_Hellstr=C3=B6m?= , Rodrigo Vivi , Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Jason Gunthorpe , John Hubbard , Muchun Song , Oscar Salvador , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Youngjun Park Cc: "Lorenzo Stoakes (ARM)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, intel-xe@lists.freedesktop.org, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=10061; i=ljs@kernel.org; h=from:subject:message-id; bh=c33SLNy9lX4ny9o263CYOjSEcyZN/XsrfEsxty/Rydo=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLJK3lzQ/npIuoyt1HXLA52ED/qC4dd5XzHYKW0XEuE7k HIn8FVyRykLgxgXg6yYIsvzL+L7g0TC5nVe8HeDmcPKBDKEgYtTACYilMLI0LZS/ZSJb4zMLrXa H7NvNHdyJLlJrqsTOP10Toe4md6NOkaGOStSu7+n+Ux/vGvrigDXN27zm1nfcrqXiWTmrnfbtWs eBwA= X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 Now we have introduced the VMA anonymous page offset attribute and update it when VMAs are manipulated, update VMA merge tests to assert that the anonymous page offset is as expected. Also update instances where we could use vma_start_pgoff() to do so. Signed-off-by: Lorenzo Stoakes (ARM) Acked-by: David Hildenbrand (Arm) --- tools/testing/vma/tests/merge.c | 45 ++++++++++++++++++++++++++++++++-----= ---- 1 file changed, 36 insertions(+), 9 deletions(-) diff --git a/tools/testing/vma/tests/merge.c b/tools/testing/vma/tests/merg= e.c index 48418b82b01d..acaab282939c 100644 --- a/tools/testing/vma/tests/merge.c +++ b/tools/testing/vma/tests/merge.c @@ -121,6 +121,7 @@ static bool test_simple_merge(void) ASSERT_EQ(vma->vm_start, 0); ASSERT_EQ(vma->vm_end, 0x3000); ASSERT_EQ(vma_start_pgoff(vma), 0); + ASSERT_EQ(vma_start_anon_pgoff(vma), 0); ASSERT_FLAGS_SAME_MASK(&vma->flags, vma_flags); =20 detach_free_vma(vma); @@ -153,6 +154,7 @@ static bool test_simple_modify(void) ASSERT_EQ(vma->vm_start, 0x1000); ASSERT_EQ(vma->vm_end, 0x2000); ASSERT_EQ(vma_start_pgoff(vma), 1); + ASSERT_EQ(vma_start_anon_pgoff(vma), 1); =20 /* * Now walk through the three split VMAs and make sure they are as @@ -165,6 +167,7 @@ static bool test_simple_modify(void) ASSERT_EQ(vma->vm_start, 0); ASSERT_EQ(vma->vm_end, 0x1000); ASSERT_EQ(vma_start_pgoff(vma), 0); + ASSERT_EQ(vma_start_anon_pgoff(vma), 0); =20 detach_free_vma(vma); vma_iter_clear(&vmi); @@ -174,6 +177,7 @@ static bool test_simple_modify(void) ASSERT_EQ(vma->vm_start, 0x1000); ASSERT_EQ(vma->vm_end, 0x2000); ASSERT_EQ(vma_start_pgoff(vma), 1); + ASSERT_EQ(vma_start_anon_pgoff(vma), 1); =20 detach_free_vma(vma); vma_iter_clear(&vmi); @@ -183,6 +187,7 @@ static bool test_simple_modify(void) ASSERT_EQ(vma->vm_start, 0x2000); ASSERT_EQ(vma->vm_end, 0x3000); ASSERT_EQ(vma_start_pgoff(vma), 2); + ASSERT_EQ(vma_start_anon_pgoff(vma), 2); =20 detach_free_vma(vma); mtree_destroy(&mm.mm_mt); @@ -212,6 +217,7 @@ static bool test_simple_expand(void) ASSERT_EQ(vma->vm_start, 0); ASSERT_EQ(vma->vm_end, 0x3000); ASSERT_EQ(vma_start_pgoff(vma), 0); + ASSERT_EQ(vma_start_anon_pgoff(vma), 0); =20 detach_free_vma(vma); mtree_destroy(&mm.mm_mt); @@ -234,6 +240,7 @@ static bool test_simple_shrink(void) ASSERT_EQ(vma->vm_start, 0); ASSERT_EQ(vma->vm_end, 0x1000); ASSERT_EQ(vma_start_pgoff(vma), 0); + ASSERT_EQ(vma_start_anon_pgoff(vma), 0); =20 detach_free_vma(vma); mtree_destroy(&mm.mm_mt); @@ -346,6 +353,7 @@ static bool __test_merge_new(bool is_sticky, bool a_is_= sticky, bool b_is_sticky, ASSERT_EQ(vma->vm_start, 0); ASSERT_EQ(vma->vm_end, 0x5000); ASSERT_EQ(vma_start_pgoff(vma), 0); + ASSERT_EQ(vma_start_anon_pgoff(vma), 0); ASSERT_EQ(vma->anon_vma, &dummy_anon_vma); ASSERT_TRUE(vma_write_started(vma)); ASSERT_EQ(mm.map_count, 3); @@ -367,6 +375,7 @@ static bool __test_merge_new(bool is_sticky, bool a_is_= sticky, bool b_is_sticky, ASSERT_EQ(vma->vm_start, 0x6000); ASSERT_EQ(vma->vm_end, 0x9000); ASSERT_EQ(vma_start_pgoff(vma), 6); + ASSERT_EQ(vma_start_anon_pgoff(vma), 6); ASSERT_EQ(vma->anon_vma, &dummy_anon_vma); ASSERT_TRUE(vma_write_started(vma)); ASSERT_EQ(mm.map_count, 3); @@ -387,6 +396,7 @@ static bool __test_merge_new(bool is_sticky, bool a_is_= sticky, bool b_is_sticky, ASSERT_EQ(vma->vm_start, 0); ASSERT_EQ(vma->vm_end, 0x9000); ASSERT_EQ(vma_start_pgoff(vma), 0); + ASSERT_EQ(vma_start_anon_pgoff(vma), 0); ASSERT_EQ(vma->anon_vma, &dummy_anon_vma); ASSERT_TRUE(vma_write_started(vma)); ASSERT_EQ(mm.map_count, 2); @@ -407,6 +417,7 @@ static bool __test_merge_new(bool is_sticky, bool a_is_= sticky, bool b_is_sticky, ASSERT_EQ(vma->vm_start, 0xa000); ASSERT_EQ(vma->vm_end, 0xc000); ASSERT_EQ(vma_start_pgoff(vma), 0xa); + ASSERT_EQ(vma_start_anon_pgoff(vma), 0xa); ASSERT_EQ(vma->anon_vma, &dummy_anon_vma); ASSERT_TRUE(vma_write_started(vma)); ASSERT_EQ(mm.map_count, 2); @@ -426,6 +437,7 @@ static bool __test_merge_new(bool is_sticky, bool a_is_= sticky, bool b_is_sticky, ASSERT_EQ(vma->vm_start, 0); ASSERT_EQ(vma->vm_end, 0xc000); ASSERT_EQ(vma_start_pgoff(vma), 0); + ASSERT_EQ(vma_start_anon_pgoff(vma), 0); ASSERT_EQ(vma->anon_vma, &dummy_anon_vma); ASSERT_TRUE(vma_write_started(vma)); ASSERT_EQ(mm.map_count, 1); @@ -446,6 +458,7 @@ static bool __test_merge_new(bool is_sticky, bool a_is_= sticky, bool b_is_sticky, ASSERT_EQ(vma->vm_start, 0); ASSERT_EQ(vma->vm_end, 0xc000); ASSERT_EQ(vma_start_pgoff(vma), 0); + ASSERT_EQ(vma_start_anon_pgoff(vma), 0); ASSERT_EQ(vma->anon_vma, &dummy_anon_vma); =20 detach_free_vma(vma); @@ -642,7 +655,8 @@ static bool test_vma_merge_with_close(void) ASSERT_EQ(vmg.state, VMA_MERGE_SUCCESS); ASSERT_EQ(vma_prev->vm_start, 0); ASSERT_EQ(vma_prev->vm_end, 0x5000); - ASSERT_EQ(vma_prev->vm_pgoff, 0); + ASSERT_EQ(vma_start_pgoff(vma_prev), 0); + ASSERT_EQ(vma_start_anon_pgoff(vma_prev), 0); =20 ASSERT_EQ(cleanup_mm(&mm, &vmi), 2); =20 @@ -753,7 +767,8 @@ static bool test_vma_merge_with_close(void) ASSERT_EQ(vmg.state, VMA_MERGE_SUCCESS); ASSERT_EQ(vma_prev->vm_start, 0); ASSERT_EQ(vma_prev->vm_end, 0x5000); - ASSERT_EQ(vma_prev->vm_pgoff, 0); + ASSERT_EQ(vma_start_pgoff(vma_prev), 0); + ASSERT_EQ(vma_start_anon_pgoff(vma_prev), 0); =20 ASSERT_EQ(cleanup_mm(&mm, &vmi), 2); =20 @@ -808,6 +823,7 @@ static bool test_vma_merge_new_with_close(void) ASSERT_EQ(vma->vm_start, 0); ASSERT_EQ(vma->vm_end, 0x5000); ASSERT_EQ(vma_start_pgoff(vma), 0); + ASSERT_EQ(vma_start_anon_pgoff(vma), 0); ASSERT_EQ(vma->vm_ops, &vm_ops); ASSERT_TRUE(vma_write_started(vma)); ASSERT_EQ(mm.map_count, 2); @@ -863,11 +879,13 @@ static bool __test_merge_existing(bool prev_is_sticky= , bool middle_is_sticky, bo ASSERT_EQ(vmg.state, VMA_MERGE_SUCCESS); ASSERT_EQ(vma_next->vm_start, 0x3000); ASSERT_EQ(vma_next->vm_end, 0x9000); - ASSERT_EQ(vma_next->vm_pgoff, 3); + ASSERT_EQ(vma_start_pgoff(vma_next), 3); + ASSERT_EQ(vma_start_anon_pgoff(vma_next), 3); ASSERT_EQ(vma_next->anon_vma, &dummy_anon_vma); ASSERT_EQ(vma->vm_start, 0x2000); ASSERT_EQ(vma->vm_end, 0x3000); ASSERT_EQ(vma_start_pgoff(vma), 2); + ASSERT_EQ(vma_start_anon_pgoff(vma), 2); ASSERT_TRUE(vma_write_started(vma)); ASSERT_TRUE(vma_write_started(vma_next)); ASSERT_EQ(mm.map_count, 2); @@ -897,7 +915,8 @@ static bool __test_merge_existing(bool prev_is_sticky, = bool middle_is_sticky, bo ASSERT_EQ(vmg.state, VMA_MERGE_SUCCESS); ASSERT_EQ(vma_next->vm_start, 0x2000); ASSERT_EQ(vma_next->vm_end, 0x9000); - ASSERT_EQ(vma_next->vm_pgoff, 2); + ASSERT_EQ(vma_start_pgoff(vma_next), 2); + ASSERT_EQ(vma_start_anon_pgoff(vma_next), 2); ASSERT_EQ(vma_next->anon_vma, &dummy_anon_vma); ASSERT_TRUE(vma_write_started(vma_next)); ASSERT_EQ(mm.map_count, 1); @@ -929,11 +948,13 @@ static bool __test_merge_existing(bool prev_is_sticky= , bool middle_is_sticky, bo ASSERT_EQ(vmg.state, VMA_MERGE_SUCCESS); ASSERT_EQ(vma_prev->vm_start, 0); ASSERT_EQ(vma_prev->vm_end, 0x6000); - ASSERT_EQ(vma_prev->vm_pgoff, 0); + ASSERT_EQ(vma_start_pgoff(vma_prev), 0); + ASSERT_EQ(vma_start_anon_pgoff(vma_prev), 0); ASSERT_EQ(vma_prev->anon_vma, &dummy_anon_vma); ASSERT_EQ(vma->vm_start, 0x6000); ASSERT_EQ(vma->vm_end, 0x7000); ASSERT_EQ(vma_start_pgoff(vma), 6); + ASSERT_EQ(vma_start_anon_pgoff(vma), 6); ASSERT_TRUE(vma_write_started(vma_prev)); ASSERT_TRUE(vma_write_started(vma)); ASSERT_EQ(mm.map_count, 2); @@ -964,7 +985,8 @@ static bool __test_merge_existing(bool prev_is_sticky, = bool middle_is_sticky, bo ASSERT_EQ(vmg.state, VMA_MERGE_SUCCESS); ASSERT_EQ(vma_prev->vm_start, 0); ASSERT_EQ(vma_prev->vm_end, 0x7000); - ASSERT_EQ(vma_prev->vm_pgoff, 0); + ASSERT_EQ(vma_start_pgoff(vma_prev), 0); + ASSERT_EQ(vma_start_anon_pgoff(vma_prev), 0); ASSERT_EQ(vma_prev->anon_vma, &dummy_anon_vma); ASSERT_TRUE(vma_write_started(vma_prev)); ASSERT_EQ(mm.map_count, 1); @@ -996,7 +1018,8 @@ static bool __test_merge_existing(bool prev_is_sticky,= bool middle_is_sticky, bo ASSERT_EQ(vmg.state, VMA_MERGE_SUCCESS); ASSERT_EQ(vma_prev->vm_start, 0); ASSERT_EQ(vma_prev->vm_end, 0x9000); - ASSERT_EQ(vma_prev->vm_pgoff, 0); + ASSERT_EQ(vma_start_pgoff(vma_prev), 0); + ASSERT_EQ(vma_start_anon_pgoff(vma_prev), 0); ASSERT_EQ(vma_prev->anon_vma, &dummy_anon_vma); ASSERT_TRUE(vma_write_started(vma_prev)); ASSERT_EQ(mm.map_count, 1); @@ -1126,7 +1149,8 @@ static bool test_anon_vma_non_mergeable(void) ASSERT_EQ(vmg.state, VMA_MERGE_SUCCESS); ASSERT_EQ(vma_prev->vm_start, 0); ASSERT_EQ(vma_prev->vm_end, 0x7000); - ASSERT_EQ(vma_prev->vm_pgoff, 0); + ASSERT_EQ(vma_start_pgoff(vma_prev), 0); + ASSERT_EQ(vma_start_anon_pgoff(vma_prev), 0); ASSERT_TRUE(vma_write_started(vma_prev)); ASSERT_FALSE(vma_write_started(vma_next)); =20 @@ -1157,7 +1181,8 @@ static bool test_anon_vma_non_mergeable(void) ASSERT_EQ(vmg.state, VMA_MERGE_SUCCESS); ASSERT_EQ(vma_prev->vm_start, 0); ASSERT_EQ(vma_prev->vm_end, 0x7000); - ASSERT_EQ(vma_prev->vm_pgoff, 0); + ASSERT_EQ(vma_start_pgoff(vma_prev), 0); + ASSERT_EQ(vma_start_anon_pgoff(vma_prev), 0); ASSERT_TRUE(vma_write_started(vma_prev)); ASSERT_FALSE(vma_write_started(vma_next)); =20 @@ -1419,6 +1444,7 @@ static bool test_merge_extend(void) ASSERT_EQ(vma->vm_start, 0); ASSERT_EQ(vma->vm_end, 0x4000); ASSERT_EQ(vma_start_pgoff(vma), 0); + ASSERT_EQ(vma_start_anon_pgoff(vma), 0); ASSERT_TRUE(vma_write_started(vma)); ASSERT_EQ(mm.map_count, 1); =20 @@ -1459,6 +1485,7 @@ static bool test_expand_only_mode(void) ASSERT_EQ(vma->vm_start, 0x3000); ASSERT_EQ(vma->vm_end, 0x9000); ASSERT_EQ(vma_start_pgoff(vma), 3); + ASSERT_EQ(vma_start_anon_pgoff(vma), 3); ASSERT_TRUE(vma_write_started(vma)); ASSERT_EQ(vma_iter_addr(&vmi), 0x3000); vma_assert_attached(vma); --=20 2.55.0 From nobody Wed Sep 30 20:13:06 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 07AA03ED5A7; Thu, 6 Aug 2026 20:27:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786048064; cv=none; b=Tsr9yvKPhvxLUVYHpU8u4RDAKyO070qf7KTLwePkzPmqs5duuHIkIW+5LWkijjIpVxl4C+S7Z50q4Noiqhq4iTiwM06C3T6xJj9U4d0hwCrSr4Dpka11+GiGXQY9/zxGptYcOB93zjnD5VamArKAzRLnNeYNQ/xO2ujyoIQ1bks= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786048064; c=relaxed/simple; bh=dwMvzFqQTQnP1VbLMwGR/grRN4JTFJuzh0kdCCF1g9s=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; 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charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260806-b4-scalable-cow-virt-pgoff-v4-16-ab318a350404@kernel.org> References: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> In-Reply-To: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> To: Andrew Morton , David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Miaohe Lin , Naoya Horiguchi , Rik van Riel , Harry Yoo , Lance Yang , Kees Cook , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Usama Arif , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Peter Xu , Xu Xin , Chengming Zhou , Arnd Bergmann , Greg Kroah-Hartman , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Sven Schnelle , Alex Deucher , =?utf-8?q?Christian_K=C3=B6nig?= , David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Boris Brezillon , Steven Price , Liviu Dudau , Huang Rui , Matthew Auld , =?utf-8?q?Thomas_Hellstr=C3=B6m?= , Rodrigo Vivi , Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Jason Gunthorpe , John Hubbard , Muchun Song , Oscar Salvador , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Youngjun Park Cc: "Lorenzo Stoakes (ARM)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, intel-xe@lists.freedesktop.org, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=2975; i=ljs@kernel.org; h=from:subject:message-id; bh=dwMvzFqQTQnP1VbLMwGR/grRN4JTFJuzh0kdCCF1g9s=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLJK3lysCLqS22lc/DEvTjyMm4erKrXupsb6VfvqGjd32 55842HXUcrCIMbFICumyPL8i/j+IJGweZ0X/N1g5rAygQxh4OIUgIlkbmBkmLnNz+P3mZaNP//e VpvTuMM/JH1lZoxt1yv1wNeMf2KD1jIy9OqcM7lx65HIgSCFnuelkc5tJ7d5Mr5dX3r1sKGosVQ +DwA= X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 While maintaining anonymous page offsets for VMAs has no impact for most merge cases, it does impact MAP_PRIVATE-mapped file-backed mappings which happen to have matching page offset but not matching anonymous page offset. Assert this behaviour by attempting to map an unfaulted MAP_PRIVATE-memfd region with a faulted one with compatible file page offsets but incompatible anonymous page offsets. Signed-off-by: Lorenzo Stoakes (ARM) Acked-by: David Hildenbrand (Arm) --- tools/testing/selftests/mm/merge.c | 57 ++++++++++++++++++++++++++++++++++= ++++ 1 file changed, 57 insertions(+) diff --git a/tools/testing/selftests/mm/merge.c b/tools/testing/selftests/m= m/merge.c index 519e5ac02db7..cb7cdb6b7ada 100644 --- a/tools/testing/selftests/mm/merge.c +++ b/tools/testing/selftests/mm/merge.c @@ -1305,6 +1305,63 @@ TEST_F(merge, merge_vmas_with_mseal) ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr + 2 * page_size); } =20 +TEST_F(merge, anon_and_page_offset_mismatch_memfd) +{ + struct procmap_fd *procmap =3D &self->procmap; + unsigned int page_size =3D self->page_size; + char *carveout =3D self->carveout; + char *ptr, *ptr2; + int fd; + + /* Create a 10 page memfd descriptor. */ + fd =3D memfd_create("anon_page_offset_test", MFD_CLOEXEC); + ASSERT_NE(fd, -1); + ASSERT_EQ(ftruncate(fd, 10 * page_size), 0); + + /* Map a region using the memfd at page offset 0. */ + ptr =3D mmap(carveout, 5 * page_size, PROT_READ | PROT_WRITE, + MAP_FIXED | MAP_PRIVATE, fd, 0); + ASSERT_NE(ptr, MAP_FAILED); + + /* + * Map another separately, and fault in, at page offset 5: + * + * |-----------| |---------| + * | unfaulted | | faulted | + * |-----------| |---------| + */ + ptr2 =3D mmap(&carveout[10 * page_size], 5 * page_size, + PROT_READ | PROT_WRITE, MAP_FIXED | MAP_PRIVATE, + fd, 5 * page_size); + ASSERT_NE(ptr2, MAP_FAILED); + ptr2[0] =3D 'x'; + + /* + * Now move it in place: + * + * |----------| + * | | + * v | + * |-----------| |---------| + * | unfaulted | | faulted | + * |-----------| |---------| + * + * Because the anonymous page offset of the faulted region is now + * &carveout[10 * page_size], despite the two regions being mergeable + * due to file page offset, they are NOT mergeable due to anonymous + * page offset. + */ + ptr2 =3D sys_mremap(ptr2, 5 * page_size, 5 * page_size, + MREMAP_MAYMOVE | MREMAP_FIXED, + &carveout[5 * page_size]); + ASSERT_NE(ptr2, MAP_FAILED); + + /* Assert that they did not merge. */ + ASSERT_TRUE(find_vma_procmap(procmap, ptr)); + ASSERT_EQ(procmap->query.vma_start, (unsigned long)ptr); + ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr + 5 * page_size); +} + TEST_F(merge_with_fork, mremap_faulted_to_unfaulted_prev) { struct procmap_fd *procmap =3D &self->procmap; --=20 2.55.0 From nobody Wed Sep 30 20:13:06 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 93A74373BE6; Thu, 6 Aug 2026 20:28:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786048085; cv=none; b=ru6a/b2DJVpj5+CpvndkR/gL8Mmpt1HQsAnnzL3bZrCMl6tl4/E4gA1C4ckGTWlsJG0m0H4tr8gT7yeuD5OnSJHySZSz1HclIsqjs1uEmaQlqZG/fvsF6Aot4/D8vytt0/W4BRgwYEJN8W1xLCyb+ktsQH4wNjpMLCXVscnirW8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; 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charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260806-b4-scalable-cow-virt-pgoff-v4-17-ab318a350404@kernel.org> References: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> In-Reply-To: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> To: Andrew Morton , David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Miaohe Lin , Naoya Horiguchi , Rik van Riel , Harry Yoo , Lance Yang , Kees Cook , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Usama Arif , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Peter Xu , Xu Xin , Chengming Zhou , Arnd Bergmann , Greg Kroah-Hartman , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Sven Schnelle , Alex Deucher , =?utf-8?q?Christian_K=C3=B6nig?= , David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Boris Brezillon , Steven Price , Liviu Dudau , Huang Rui , Matthew Auld , =?utf-8?q?Thomas_Hellstr=C3=B6m?= , Rodrigo Vivi , Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Jason Gunthorpe , John Hubbard , Muchun Song , Oscar Salvador , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Youngjun Park Cc: "Lorenzo Stoakes (ARM)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, intel-xe@lists.freedesktop.org, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=10732; i=ljs@kernel.org; h=from:subject:message-id; bh=4d9DHPORBIDZZPM/wxZbc+1vsP2UYLtzsqY44MmiFUU=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLJK3lyU8bliOqXykajsS8vcCMnNLrdWR37x+bFNeOnJ2 r8C91VvdpSyMIhxMciKKbI8/yK+P0gkbF7nBX83mDmsTCBDGLg4BWAiHYoM/wyesG6rCy1nD525 eXmqbqoVw+mDevauGmt4l8ufSX9wbDcjwz7R13GivatO7Cq4c6ug79rhJGbuv8Hvw+Wnbzkrvcr 0FScA X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 In order to use mmap_prepare() with MAP_PRIVATE mappings of /dev/zero without the success_hook hack we explicitly permitted mmap_prepare handlers to set NULL vm_ops. However this is dangerous and we really only want to allow this for MAP_PRIVATE-mapped /dev/zero. Make it possible to explicitly identify /dev/zero by setting a global DEVZERO_MINOR device minor number then explicitly check for this in mmap code for a MAP_PRIVATE mapping and only set the VMA anonymous if we have positively identified it. Then remove all ability for mmap_prepare or mmap hooks to set a VMA anonymous and update mmap_zero_prepare() to leave it to the core mmap code to mark the VMA anonymous. Note that this disallows nested MAP_PRIVATE-mappings of /dev/zero regions. Doing this would be broken in any case. We therefore do not need to update the mmap_prepare() compatibility layer to reflect these changes, as the mmap hook check suffices to disallow this behaviour. Now we're setting vma->vm_ops to NULL for an mmap_prepare-initialised MAP_PRIVATE-/dev/zero mapping, we have to avoid a subtle issue when updating user-defined fields via set_vma_user_defined_fields(). The default for vma->vm_ops for all mmap_prepare-initialised mappings is vma_dummy_vm_ops, so map->vm_ops will be set to this and setting vma->vm_ops to this will render the VMA mistakenly non-anon. In general, we should never be setting user-defined fields for an anonymous VMA, so explicitly check for this to avoid doing so for the one case where a mapping can be both mmap_prepare and anonymous. In the case of legacy ->mmap hooks some drivers may set vma->vm_ops NULL believing this is the equivalent of setting no VMA operations. Therefore update mmap_file() to correct this by setting dummy VMA operations if this occurs. An example of this is drm_gem_shmem_mmap() which deliberately clears vma->vm_ops before handing the VMA to dma-buf. Cases such as this will be updated when they are converted to mmap_prepare. Also, in order to avoid a single commit bisection hazard, add a temporary workaround to set the VMA anonymous only after vma->vm_file is assigned in __mmap_new_file_vma(). This is because vma_set_range() calls vma_set_pgoff() and assert_sane_pgoff() in turn, prior to the vma->vm_file being assigned. If we set the VMA anonymous early then this assert will fail. This is removed in the subsequent commit. Also update the VMA userland tests to reflect the change. Signed-off-by: Lorenzo Stoakes (ARM) --- drivers/char/mem.c | 8 ++----- include/linux/mm.h | 3 +++ mm/internal.h | 17 ++++++++------- mm/vma.c | 46 ++++++++++++++++++++++++++++++++++---= ---- mm/vma_internal.h | 1 + tools/testing/vma/include/dup.h | 36 ++++++++++++++++++++++++++++++++ 6 files changed, 90 insertions(+), 21 deletions(-) diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 63253d1de5d7..dcfd896b733d 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -506,11 +506,7 @@ static int mmap_zero_prepare(struct vm_area_desc *desc) if (vma_desc_test(desc, VMA_SHARED_BIT)) return shmem_zero_setup_desc(desc); =20 - /* - * This is a highly unique situation where we mark a MAP_PRIVATE mapping - * of /dev/zero anonymous, despite it not being. - */ - vma_desc_set_anonymous(desc); + /* MAP_PRIVATE semantics are taken care for us by core mm. */ return 0; } =20 @@ -698,7 +694,7 @@ static const struct memdev { #ifdef CONFIG_DEVPORT [4] =3D { "port", &port_fops, 0, 0 }, #endif - [5] =3D { "zero", &zero_fops, FMODE_NOWAIT, 0666 }, + [DEVZERO_MINOR] =3D { "zero", &zero_fops, FMODE_NOWAIT, 0666 }, [7] =3D { "full", &full_fops, 0, 0666 }, [8] =3D { "random", &random_fops, FMODE_NOWAIT, 0666 }, [9] =3D { "urandom", &urandom_fops, FMODE_NOWAIT, 0666 }, diff --git a/include/linux/mm.h b/include/linux/mm.h index da36a6cc907c..b54bdbbf3906 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -740,6 +740,9 @@ static inline bool fault_flag_allow_retry_first(enum fa= ult_flag flags) { FAULT_FLAG_INTERRUPTIBLE, "INTERRUPTIBLE" }, \ { FAULT_FLAG_VMA_LOCK, "VMA_LOCK" } =20 +/* /dev/zero minor device number. Special due to MAP_PRIVATE semantics. */ +#define DEVZERO_MINOR 5 + /* * vm_fault is filled by the pagefault handler and passed to the vma's * ->fault function. The vma's ->fault is responsible for returning a bitm= ask diff --git a/mm/internal.h b/mm/internal.h index 5892b7453b54..1048d8e053fc 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -240,15 +240,18 @@ static inline int mmap_file(struct file *file, struct= vm_area_struct *vma) { int err =3D vfs_mmap(file, vma); =20 - if (likely(!err)) - return 0; - /* - * OK, we tried to call the file hook for mmap(), but an error - * arose. The mapping is in an inconsistent state and we must not invoke - * any further hooks on it. + * Either we tried to call the file hook for mmap() and an error arose + * or a driver set vma->vm_ops =3D NULL intending there to be no VMA + * operations. + * + * In the former case the VMA is in an inconsistent state and we mustn't + * invoke any further hooks on it, in the latter case the hook actually + * wanted no further hooks to be invoked, so fix both by setting dummy + * VMA ops. */ - vma->vm_ops =3D &vma_dummy_vm_ops; + if (unlikely(err || !vma->vm_ops)) + vma->vm_ops =3D &vma_dummy_vm_ops; =20 return err; } diff --git a/mm/vma.c b/mm/vma.c index 117ca94fc907..4271b5ff8137 100644 --- a/mm/vma.c +++ b/mm/vma.c @@ -2621,6 +2621,32 @@ static int __mmap_new_file_vma(struct mmap_state *ma= p, return 0; } =20 +static bool map_is_dev_zero(const struct mmap_state *map) +{ + const struct file *file =3D map->file; + struct inode *inode; + + if (!file) + return false; + inode =3D file_inode(file); + if (!S_ISCHR(inode->i_mode)) + return false; + return imajor(inode) =3D=3D MEM_MAJOR && iminor(inode) =3D=3D DEVZERO_MIN= OR; +} + +static bool map_is_private(const struct mmap_state *map) +{ + return !vma_flags_test(&map->vma_flags, VMA_SHARED_BIT); +} + +static bool map_is_anon(const struct mmap_state *map) +{ + if (!map_is_private(map)) + return false; + + return !map->file || map_is_dev_zero(map); +} + /* * __mmap_new_vma() - Allocate a new VMA for the region, as merging was not * possible. @@ -2634,8 +2660,7 @@ static int __mmap_new_file_vma(struct mmap_state *map, static int __mmap_new_vma(struct mmap_state *map, struct vm_area_struct **= vmap, struct mmap_action *action) { - const bool is_anon =3D !map->file && - !vma_flags_test(&map->vma_flags, VMA_SHARED_BIT); + const bool is_anon =3D map_is_anon(map); struct vma_iterator *vmi =3D map->vmi; int error =3D 0; struct vm_area_struct *vma; @@ -2651,7 +2676,7 @@ static int __mmap_new_vma(struct mmap_state *map, str= uct vm_area_struct **vmap, =20 vma_iter_config(vmi, map->addr, map->end); =20 - if (is_anon) + if (is_anon && !map->file) vma_set_anonymous(vma); =20 vma_set_range(vma, map->addr, map->end, map->pgoff, map->anon_pgoff); @@ -2669,6 +2694,10 @@ static int __mmap_new_vma(struct mmap_state *map, st= ruct vm_area_struct **vmap, else if (!is_anon) error =3D shmem_zero_setup(vma); =20 + /* Temporary MAP_PRIVATE-/dev/zero workaround. */ + if (is_anon && map->file) + vma_set_anonymous(vma); + if (error) goto free_iter_vma; =20 @@ -2777,6 +2806,10 @@ static int call_mmap_prepare(struct mmap_state *map, if (err) return err; =20 + /* Hooks cannot mark themselves anonymous. */ + if (!desc->vm_ops) + return -EINVAL; + err =3D call_action_prepare(map, desc); if (err) return err; @@ -2799,10 +2832,7 @@ static int call_mmap_prepare(struct mmap_state *map, static void set_vma_user_defined_fields(struct vm_area_struct *vma, struct mmap_state *map) { - if (map->vm_ops) - vma->vm_ops =3D map->vm_ops; - else /* Only /dev/zero should do this. */ - vma_set_anonymous(vma); + vma->vm_ops =3D map->vm_ops; vma->vm_private_data =3D map->vm_private_data; } =20 @@ -2882,7 +2912,7 @@ static unsigned long __mmap_region(struct file *file,= unsigned long addr, allocated_new =3D true; } =20 - if (have_mmap_prepare) + if (have_mmap_prepare && !map_is_anon(&map)) set_vma_user_defined_fields(vma, &map); =20 __mmap_complete(&map, vma); diff --git a/mm/vma_internal.h b/mm/vma_internal.h index 4d300e7bbaf4..385c0ab13777 100644 --- a/mm/vma_internal.h +++ b/mm/vma_internal.h @@ -23,6 +23,7 @@ #include #include #include +#include #include #include #include diff --git a/tools/testing/vma/include/dup.h b/tools/testing/vma/include/du= p.h index 4c58487b764e..7490e33f9316 100644 --- a/tools/testing/vma/include/dup.h +++ b/tools/testing/vma/include/dup.h @@ -15,6 +15,20 @@ struct task_struct *get_current(void); #define MMF_HAS_MDWE 28 #define current get_current() =20 +#define MINORBITS 20 +#define MINORMASK ((1U << MINORBITS) - 1) + +#define MAJOR(dev) ((unsigned int) ((dev) >> MINORBITS)) +#define MINOR(dev) ((unsigned int) ((dev) & MINORMASK)) + +#define S_IFMT 00170000 +#define S_IFCHR 0020000 + +#define S_ISCHR(m) (((m) & S_IFMT) =3D=3D S_IFCHR) + +#define MEM_MAJOR 1 +#define DEVZERO_MINOR 5 + /* * Define the task command name length as enum, then it can be visible to * BPF programs. @@ -23,6 +37,8 @@ enum { TASK_COMM_LEN =3D 16, }; =20 +typedef unsigned short umode_t; + /* PARTIALLY implemented types. */ struct mm_struct { struct maple_tree mm_mt; @@ -45,6 +61,10 @@ struct address_space { unsigned long flags; atomic_t i_mmap_writable; }; +struct inode { + umode_t i_mode; + dev_t i_rdev; +}; struct file_operations { int (*mmap)(struct file *, struct vm_area_struct *); int (*mmap_prepare)(struct vm_area_desc *); @@ -52,6 +72,7 @@ struct file_operations { struct file { struct address_space *f_mapping; const struct file_operations *f_op; + struct inode *f_inode; }; struct anon_vma_chain { struct anon_vma *anon_vma; @@ -1644,3 +1665,18 @@ static inline pgoff_t linear_anon_page_index(const s= truct vm_area_struct *vma, =20 return pgoff; } + +static inline struct inode *file_inode(const struct file *f) +{ + return f->f_inode; +} + +static inline unsigned iminor(const struct inode *inode) +{ + return MINOR(inode->i_rdev); +} + +static inline unsigned imajor(const struct inode *inode) +{ + return MAJOR(inode->i_rdev); +} --=20 2.55.0 From nobody Wed Sep 30 20:13:06 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 46E8444A3E9; 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dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="oi8V/AQa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 02BC61F00A3A; Thu, 6 Aug 2026 20:28:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786048104; bh=s614eIYIfGzeFDcqmL80845cOq/GnH2yhXjc1z/Xs3o=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=oi8V/AQazUITPY39thPVTqxXw0vxr3S3Qg2eMmuClvX+TlrdmvYfnj5YVnPZMVyJ+ 17mHgRQlDSmUqgVu1vrg5lTcWmbbvW48uQfHxDmnuvMVU0mOFkfAsXHy03EOmjQ1rA Ma5ZWc8LKU/U1AeUjVAuH4kR0pBWC+7XwuMV1BrSA/zO1mfs+Ik0u+7lEtUSV/SC2J qV9vnDSkeKzTs5MSk/N4LeyaCAaXQUGMzjOl1/xZ6RzSIV12333ep3UU5Dw6mVw2gh tVczRe067Sb/zlB+bP+/WkO1cdcmOwdpoQTziy0R/KEP3BRkdfsGV6etm/ILB6+4Hk 1uwbLeJxqT7Pw== From: "Lorenzo Stoakes (ARM)" Date: Thu, 06 Aug 2026 21:21:43 +0100 Subject: [PATCH v4 18/20] mm/vma: make MAP_PRIVATE-mapped /dev/zero mappings truly anonymous Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260806-b4-scalable-cow-virt-pgoff-v4-18-ab318a350404@kernel.org> References: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> In-Reply-To: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> To: Andrew Morton , David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Miaohe Lin , Naoya Horiguchi , Rik van Riel , Harry Yoo , Lance Yang , Kees Cook , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Usama Arif , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Peter Xu , Xu Xin , Chengming Zhou , Arnd Bergmann , Greg Kroah-Hartman , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Sven Schnelle , Alex Deucher , =?utf-8?q?Christian_K=C3=B6nig?= , David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Boris Brezillon , Steven Price , Liviu Dudau , Huang Rui , Matthew Auld , =?utf-8?q?Thomas_Hellstr=C3=B6m?= , Rodrigo Vivi , Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Jason Gunthorpe , John Hubbard , Muchun Song , Oscar Salvador , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Youngjun Park Cc: "Lorenzo Stoakes (ARM)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, intel-xe@lists.freedesktop.org, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=8535; i=ljs@kernel.org; h=from:subject:message-id; bh=xdiGzXr/KOMXOTiCtq5gy7iFQAvBdUR/MoFUcyPdwSY=; b=kA0DAAoWz53NioHifxQByyZiAGp07NGij7MenxMs4hFrbpxKbX4SONBw+Kwckur8VHwzrdiTh 4h1BAAWCgAdFiEE5/QXv1IUVp6J0E9Gz53NioHifxQFAmp07NEACgkQz53NioHifxRpXwEAxEUt 4VChWFpH3aNfi4wLpFOEqIUfcti8xIHdex2D0WAA/0SfNKmmDxjXLbVv2eFuKwrndL8TdVG0xQ2 uBFNAth4N X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 When mapping /dev/zero with MAP_PRIVATE, one ends up with strange VMAs originating from Linux's distant past. These have vma->vm_file set but NULL vma->vm_ops, meaning they satisfy vma_is_anonymous() but otherwise resemble a file-backed VMA. The introduction of anonymous page offsets and their subsequent use as indexes for MAP_PRIVATE-file-backed mappings mean the rmap does the right thing with these but we are left with inconsistencies. The vma_start_pgoff(vma) =3D=3D vma_start_anon_pgoff(vma) invariant is true= for all other anonymous VMAs, but not these. These VMAs are also observable as files in /proc//[maps, smaps, map_files] but otherwise behave like anonymous mappings. Therefore let's make these VMAs actually anonymous at mapping time which will activate the anonymous code path for mappings. This means we no longer have to account for this discrepancy anywhere and no longer have to think about these at all. This is user-observable, as MAP_PRIVATE-/dev/zero will no longer appear in procfs as a file-backed mapping, but the impact of this change should be low as likely nobody is relying upon this. However in any case, in using MAP_PRIVATE-/dev/zero they are explicitly asking anonymous memory, so no longer seeing these as file mappings is in fact correct. A previous commit gave us map_is_dev_zero() to positively identify these mappings, so we expressly only do so for these alone. Update assert_sane_pgoff(), the comment for vma_start_pgoff() and linear_anon_page_index() to reflect the change. We make this change in call_mmap_prepare() alone as /dev/zero has been converted to an mmap_prepare hook and we do not permit nested MAP_PRIVATE mapping of /dev/zero. We also remove the now defunct vma_desc_set_anonymous() and eliminate the temporary bisection hazard fix from the previous commit. Also update the VMA userland tests to reflect the change. Finally, update the procfs self tests proc-self-map-files-001 and proc-self-map-files-002 which both intend to map an arbitrary file MAP_PRIVATE then assert procfs state, but happen to choose /dev/zero. Fix them by updating these to /proc/self/exe which is guaranteed to be present if procfs is mounted. Signed-off-by: Lorenzo Stoakes (ARM) --- include/linux/mm.h | 10 ++------- include/linux/pagemap.h | 3 +-- mm/vma.c | 26 ++++++++++++++----= ---- mm/vma.h | 3 --- .../selftests/proc/proc-self-map-files-001.c | 2 +- .../selftests/proc/proc-self-map-files-002.c | 2 +- tools/testing/vma/include/dup.h | 3 +-- 7 files changed, 23 insertions(+), 26 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index b54bdbbf3906..0d21112a8b63 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1554,11 +1554,6 @@ static inline void vma_set_anonymous(struct vm_area_= struct *vma) vma->vm_ops =3D NULL; } =20 -static inline void vma_desc_set_anonymous(struct vm_area_desc *desc) -{ - desc->vm_ops =3D NULL; -} - static inline bool vma_is_anonymous(const struct vm_area_struct *vma) { return !vma->vm_ops; @@ -4355,9 +4350,8 @@ static inline unsigned long vma_pages(const struct vm= _area_struct *vma) * If @vma is a MAP_PRIVATE file-backed mapping, then this returns the * page offset within the file. * - * Edge cases: nommu does not abide by these, MAP_PRIVATE-/dev/zero satisf= ies - * vma_is_anonymous() but has file-backed page offset, and MAP_PRIVATE-pfn= map - * regions have their page offset set to the first PFN in the range. + * Edge cases: nommu does not abide by these and CoW MAP_PRIVATE-pfnmap re= gions + * have their page offset set to the first PFN in the range. * * Returns: The page offset of the start of @vma. */ diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 0adfa6605653..939f3a5e973f 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -1128,8 +1128,7 @@ static inline pgoff_t linear_anon_page_index(const st= ruct vm_area_struct *vma, const pgoff_t pgoff =3D __linear_anon_page_index(vma, address); =20 VM_WARN_ON_ONCE(!vma_is_cow_mapping(vma)); - /* Account for MAP_PRIVATE-/dev/zero which is only semi-anonymous. */ - if (vma_is_anonymous(vma) && !vma->vm_file) + if (vma_is_anonymous(vma)) VM_WARN_ON_ONCE(pgoff !=3D linear_page_index(vma, address)); =20 return pgoff; diff --git a/mm/vma.c b/mm/vma.c index 4271b5ff8137..6db84830e88f 100644 --- a/mm/vma.c +++ b/mm/vma.c @@ -2634,6 +2634,13 @@ static bool map_is_dev_zero(const struct mmap_state = *map) return imajor(inode) =3D=3D MEM_MAJOR && iminor(inode) =3D=3D DEVZERO_MIN= OR; } =20 +static void map_set_anon(struct mmap_state *map) +{ + map->file =3D NULL; + map->vm_ops =3D NULL; + map->pgoff =3D map->addr >> PAGE_SHIFT; +} + static bool map_is_private(const struct mmap_state *map) { return !vma_flags_test(&map->vma_flags, VMA_SHARED_BIT); @@ -2641,10 +2648,7 @@ static bool map_is_private(const struct mmap_state *= map) =20 static bool map_is_anon(const struct mmap_state *map) { - if (!map_is_private(map)) - return false; - - return !map->file || map_is_dev_zero(map); + return map_is_private(map) && !map->file; } =20 /* @@ -2676,7 +2680,7 @@ static int __mmap_new_vma(struct mmap_state *map, str= uct vm_area_struct **vmap, =20 vma_iter_config(vmi, map->addr, map->end); =20 - if (is_anon && !map->file) + if (is_anon) vma_set_anonymous(vma); =20 vma_set_range(vma, map->addr, map->end, map->pgoff, map->anon_pgoff); @@ -2694,10 +2698,6 @@ static int __mmap_new_vma(struct mmap_state *map, st= ruct vm_area_struct **vmap, else if (!is_anon) error =3D shmem_zero_setup(vma); =20 - /* Temporary MAP_PRIVATE-/dev/zero workaround. */ - if (is_anon && map->file) - vma_set_anonymous(vma); - if (error) goto free_iter_vma; =20 @@ -2826,6 +2826,14 @@ static int call_mmap_prepare(struct mmap_state *map, map->vm_ops =3D desc->vm_ops; map->vm_private_data =3D desc->private_data; =20 + /* + * MAP_PRIVATE-/dev/zero mappings are an ancient way of getting + * anonymous mappings. Rather than allowing these mappings to be odd + * outliers, simply make them truly anonymous. + */ + if (map_is_private(map) && map_is_dev_zero(map)) + map_set_anon(map); + return 0; } =20 diff --git a/mm/vma.h b/mm/vma.h index 024fabe63560..e97bd2dfa786 100644 --- a/mm/vma.h +++ b/mm/vma.h @@ -267,9 +267,6 @@ static inline void assert_sane_pgoff(struct vm_area_str= uct *vma, pgoff_t pgoff) */ if (!vma_is_anonymous(vma)) return; - /* MAP_PRIVATE-/dev/zero is anon, non-NULL vm_file, but has file pgoff. */ - if (vma->vm_file) - return; /* If faulted in, could have been remapped. */ if (vma->anon_vma) return; diff --git a/tools/testing/selftests/proc/proc-self-map-files-001.c b/tools= /testing/selftests/proc/proc-self-map-files-001.c index 4209c64283d6..bbca9f9e2743 100644 --- a/tools/testing/selftests/proc/proc-self-map-files-001.c +++ b/tools/testing/selftests/proc/proc-self-map-files-001.c @@ -51,7 +51,7 @@ int main(void) int fd; unsigned long a, b; =20 - fd =3D open("/dev/zero", O_RDONLY); + fd =3D open("/proc/self/exe", O_RDONLY); if (fd =3D=3D -1) return 1; =20 diff --git a/tools/testing/selftests/proc/proc-self-map-files-002.c b/tools= /testing/selftests/proc/proc-self-map-files-002.c index e6aa00a183bc..5786cdffbbf6 100644 --- a/tools/testing/selftests/proc/proc-self-map-files-002.c +++ b/tools/testing/selftests/proc/proc-self-map-files-002.c @@ -57,7 +57,7 @@ int main(void) int fd; unsigned long a, b; =20 - fd =3D open("/dev/zero", O_RDONLY); + fd =3D open("/proc/self/exe", O_RDONLY); if (fd =3D=3D -1) return 1; =20 diff --git a/tools/testing/vma/include/dup.h b/tools/testing/vma/include/du= p.h index 7490e33f9316..aee36707abdd 100644 --- a/tools/testing/vma/include/dup.h +++ b/tools/testing/vma/include/dup.h @@ -1659,8 +1659,7 @@ static inline pgoff_t linear_anon_page_index(const st= ruct vm_area_struct *vma, const pgoff_t pgoff =3D __linear_anon_page_index(vma, address); =20 VM_WARN_ON_ONCE(!vma_is_cow_mapping(vma)); - /* Account for MAP_PRIVATE-/dev/zero which is only semi-anonymous. */ - if (vma_is_anonymous(vma) && !vma->vm_file) + if (vma_is_anonymous(vma)) VM_WARN_ON_ONCE(pgoff !=3D linear_page_index(vma, address)); =20 return pgoff; --=20 2.55.0 From nobody Wed Sep 30 20:13:06 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 308224DB55C; Thu, 6 Aug 2026 20:28:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786048126; cv=none; b=PdOmmJ4aQqN7TWb0pUBs2RUNtUU1RhLOORJ/Rijp59WKLvHjcdBD9szTcJYu7PRG301RcjVd1jr4Y7arbY10YTUDt1OR3ixPhNfh9f9AP8t4BYwbctMz6jXP0GNC/xWYF+2AW9yb8lAjF4JV255KE9wDdW8GNa9r3Qc4Alks6gA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786048126; c=relaxed/simple; bh=DUhVb18/709QqMXpsBMKsajnvyrOaD/dsQci+RSxB/o=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=QndtR8RA0ieBzz8pLQbG24zgOhjneTqw4TfvWQFmLmqntGUqmHimXlBa8wDiKjIB6YED8SNDE469R9sYuT+HspinEa9ltfDCbbF9tMYuGbHlk79hcCF+554WbixI75znzrSVfmGi8ZA46wHiIE0ZaEavaANkIN5mnPiXeThjSH4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=YD4TxlIu; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="YD4TxlIu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AA4BB1F000E9; Thu, 6 Aug 2026 20:28:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786048124; bh=9ay272yfGladg93XZw7/G7XjdroJLmcVvLtXjw10G00=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=YD4TxlIuxzp5v5Z0ZTEodCRXT8YGzqpa/pxpaWKPvQtUbMFMXa2a/qwHZ5bHfXywc IURsjSYbpRrj/JgN/dgejv1NKIRo671upsDn0dO++7Ik7SMxy4jn9JKKzsJztBoNi7 mr7bcXfaZJidIQLujafYpaoUPrilhim3f91/DZPdrHk1F0X7XnaOrxW7T9CW/GFnh+ JznKvb+O6fxZEbJmlRPmnFQjBOmOU/9xv2jvq7CMcblsTvxhJgJ4ih8couGTCweKZZ OJ8rq8uytZHKRS4sc2XXejCQMrK3vTIs3ha3hf1+gr0E4PbfD9E+P8eWtBIYa7GXCO 6m1UOvM5fNvDA== From: "Lorenzo Stoakes (ARM)" Date: Thu, 06 Aug 2026 21:21:44 +0100 Subject: [PATCH v4 19/20] tools/testing/vma: add test to assert MAP_PRIVATE-/dev/zero is anon Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260806-b4-scalable-cow-virt-pgoff-v4-19-ab318a350404@kernel.org> References: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> In-Reply-To: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> To: Andrew Morton , David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Miaohe Lin , Naoya Horiguchi , Rik van Riel , Harry Yoo , Lance Yang , Kees Cook , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Usama Arif , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Peter Xu , Xu Xin , Chengming Zhou , Arnd Bergmann , Greg Kroah-Hartman , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Sven Schnelle , Alex Deucher , =?utf-8?q?Christian_K=C3=B6nig?= , David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Boris Brezillon , Steven Price , Liviu Dudau , Huang Rui , Matthew Auld , =?utf-8?q?Thomas_Hellstr=C3=B6m?= , Rodrigo Vivi , Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Jason Gunthorpe , John Hubbard , Muchun Song , Oscar Salvador , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Youngjun Park Cc: "Lorenzo Stoakes (ARM)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, intel-xe@lists.freedesktop.org, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=2651; i=ljs@kernel.org; h=from:subject:message-id; bh=DUhVb18/709QqMXpsBMKsajnvyrOaD/dsQci+RSxB/o=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLJK3lxMPHH2k32mEdv5l05HBRk8s5YcP77yGMs873QpJ amKzyFXO0pZGMS4GGTFFFmefxHfHyQSNq/zgr8bzBxWJpAhDFycAjCRO2cYGW7x7VtwXGHGux2p JSIBGxNmLvt/4mREzMsWK8GlNXmVaUsZ/ud/7Q5pO7NsueREbWXFBqlZN7OOfmh8pPT4U+3X33M esvABAA== X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 Now we've made MAP_PRIVATE-mapped /dev/zero mappings truly anonymous, add a VMA userland test to assert that this is the case and everything is as we would expect for an anonymous mapping. Signed-off-by: Lorenzo Stoakes (ARM) Acked-by: David Hildenbrand (Arm) --- tools/testing/vma/include/dup.h | 1 + tools/testing/vma/tests/mmap.c | 50 +++++++++++++++++++++++++++++++++++++= ++++ 2 files changed, 51 insertions(+) diff --git a/tools/testing/vma/include/dup.h b/tools/testing/vma/include/du= p.h index aee36707abdd..41203b1c2323 100644 --- a/tools/testing/vma/include/dup.h +++ b/tools/testing/vma/include/dup.h @@ -20,6 +20,7 @@ struct task_struct *get_current(void); =20 #define MAJOR(dev) ((unsigned int) ((dev) >> MINORBITS)) #define MINOR(dev) ((unsigned int) ((dev) & MINORMASK)) +#define MKDEV(ma, mi) (((ma) << MINORBITS) | (mi)) =20 #define S_IFMT 00170000 #define S_IFCHR 0020000 diff --git a/tools/testing/vma/tests/mmap.c b/tools/testing/vma/tests/mmap.c index c85bc000d1cb..ebe01362e530 100644 --- a/tools/testing/vma/tests/mmap.c +++ b/tools/testing/vma/tests/mmap.c @@ -45,7 +45,57 @@ static bool test_mmap_region_basic(void) return true; } =20 +static int dummy_mmap_prepare(struct vm_area_desc *desc) +{ + return 0; +} + +static bool test_pure_anon_dev_zero(void) +{ + const vma_flags_t vma_flags =3D mk_vma_flags(VMA_READ_BIT, VMA_WRITE_BIT, + VMA_MAYREAD_BIT, VMA_MAYWRITE_BIT); + const struct file_operations f_op =3D { + .mmap_prepare =3D dummy_mmap_prepare, + }; + struct inode inode =3D { + .i_mode =3D S_IFCHR, + .i_rdev =3D MKDEV(MEM_MAJOR, DEVZERO_MINOR), + }; + struct file file =3D { + .f_inode =3D &inode, + .f_op =3D &f_op, + }; + struct mm_struct mm =3D {}; + struct vm_area_struct *vma; + unsigned long addr; + VMA_ITERATOR(vmi, &mm, 0); + + current->mm =3D &mm; + + /* + * Map a MAP_PRIVATE-/dev/zero mapping at address 0x300000 with a page + * offset of 0x10, which we expect to be reset to the anonymous page + * offset. + */ + addr =3D __mmap_region(&file, 0x300000, 0x3000, vma_flags, 0x10, NULL); + ASSERT_EQ(addr, 0x300000); + + /* Assert that it truly is an anonymous mapping. */ + vma =3D vma_lookup(&mm, addr); + ASSERT_NE(vma, NULL); + ASSERT_TRUE(vma_is_anonymous(vma)); + ASSERT_EQ(vma->vm_file, NULL); + ASSERT_EQ(vma->vm_private_data, NULL); + /* Expect anonymous page offsets. */ + ASSERT_EQ(vma->vm_pgoff, 0x300); + ASSERT_EQ(vma_start_anon_pgoff(vma), 0x300); + + cleanup_mm(&mm, &vmi); + return true; +} + static void run_mmap_tests(int *num_tests, int *num_fail) { TEST(mmap_region_basic); + TEST(pure_anon_dev_zero); } --=20 2.55.0 From nobody Wed Sep 30 20:13:06 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F1AC548F85B; Thu, 6 Aug 2026 20:29:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786048149; cv=none; b=P1wJrDq61Gh6IPmhLJYw8CXEPEa1CyLQhvohCp37BfmSw2GOl4wRmksNPUiOyxU/T7STr6u/yiii+ftBu6b0WffxGNOY9JLPcg1oUur1m1SMMqgdlJf2RrY5WKBFwuG0LiKiPoy0PTxp1MOga8gta91QzW1ZiuUp6IJmXPK0vRg= ARC-Message-Signature: i=1; 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b=MqixkwPXrlSArdj2AxmQRUBAZOxeLM45HENcNI18hOrmFCubXTqm3d/pW/j+GilWB 9BahqG6yE3oQZYYcsw3PW6+dCIC8tpH1E7EVsm176N3UJmTmu2M/Dq6UlGOOKi0fG/ bZWAQdPIFjolMfp+Tn/LN3PXlnONNeQMHvvqoHDq4L0yGD9qJBJnptEEtbcxSm2wLQ Z9JO6AB2xF4av8yDDgKhEnLl4sZQt4ZCyPALOpTUCNvnXwIDY6FjrcByNEoCYBm0Yl 89v/zFEEAT7TvOEzEK2scmXfAZHCbFM3Cs7QX5BVF619scXT30pbj7AwTy6jaXq0VU eOdySbmCEenGw== From: "Lorenzo Stoakes (ARM)" Date: Thu, 06 Aug 2026 21:21:45 +0100 Subject: [PATCH v4 20/20] tools/testing/selftests/mm: add MAP_PRIVATE-/dev/zero merge tests Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260806-b4-scalable-cow-virt-pgoff-v4-20-ab318a350404@kernel.org> References: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> In-Reply-To: <20260806-b4-scalable-cow-virt-pgoff-v4-0-ab318a350404@kernel.org> To: Andrew Morton , David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Miaohe Lin , Naoya Horiguchi , Rik van Riel , Harry Yoo , Lance Yang , Kees Cook , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Usama Arif , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Peter Xu , Xu Xin , Chengming Zhou , Arnd Bergmann , Greg Kroah-Hartman , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Sven Schnelle , Alex Deucher , =?utf-8?q?Christian_K=C3=B6nig?= , David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Boris Brezillon , Steven Price , Liviu Dudau , Huang Rui , Matthew Auld , =?utf-8?q?Thomas_Hellstr=C3=B6m?= , Rodrigo Vivi , Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Jason Gunthorpe , John Hubbard , Muchun Song , Oscar Salvador , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Youngjun Park Cc: "Lorenzo Stoakes (ARM)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, intel-xe@lists.freedesktop.org, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org, syzbot@syzkaller.appspotmail.com X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=4325; i=ljs@kernel.org; h=from:subject:message-id; bh=Hf1sWA2I3g3xjEoBx6Nr1xgWjzHqdTMWAurRnr10dBc=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLJK3lx8f3eBxxNuU4MJd/orhZRcbc8ErJlwcsVS4QDNx BWGF9x9O0pZGMS4GGTFFFmefxHfHyQSNq/zgr8bzBxWJpAhDFycAjCRPy8Z/llEfH7qFB7SUJnB 6yfno9ad9iN3vuQpqacrFlZ0SamUP2b4pztd5lrZobh1Z9ycDvMcn7Ak4I/HB3mXjVurlwrFbPU 0ZwQA X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 Assert that MAP_PRIVATE-mapped /dev/zero mappings behave like they are anonymous. We test both unfaulted and faulted/unfaulted merges - each with the regions having page offset of 0, which would not merge if the mappings were treated as if they were file-backed. With the recent change that makes them behave as pure anonymous mappings, the merges should succeed as their page offsets are equal to their anonymous page offsets. Tested-by: syzbot@syzkaller.appspotmail.com Signed-off-by: Lorenzo Stoakes (ARM) --- tools/testing/selftests/mm/merge.c | 104 +++++++++++++++++++++++++++++++++= ++++ 1 file changed, 104 insertions(+) diff --git a/tools/testing/selftests/mm/merge.c b/tools/testing/selftests/m= m/merge.c index cb7cdb6b7ada..19c9bf9eb9ce 100644 --- a/tools/testing/selftests/mm/merge.c +++ b/tools/testing/selftests/mm/merge.c @@ -1362,6 +1362,110 @@ TEST_F(merge, anon_and_page_offset_mismatch_memfd) ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr + 5 * page_size); } =20 +TEST_F(merge, merge_map_private_dev_zero_unfaulted) +{ + struct procmap_fd *procmap =3D &self->procmap; + unsigned int page_size =3D self->page_size; + char *carveout =3D self->carveout; + char *ptr, *ptr2; + int fd_zero; + + if (access("/dev/zero", F_OK)) + SKIP(return, "No /dev/zero."); + fd_zero =3D open("/dev/zero", O_RDWR); + ASSERT_NE(fd_zero, -1); + + /* + * Map two MAP_PRIVATE-/dev/zero VMAs next to one another with offset 0 + * each. + * + * With these being made truly anonymous upon mapping, they will + * merge. If they were file-backed VMAs the page offsets would prevent + * merge: + * + * |-----||------| |-------------| + * | ptr || ptr2 | -> | ptr | + * |-----||------| |-------------| + */ + ptr =3D mmap(carveout, 5 * page_size, PROT_READ | PROT_WRITE, + MAP_FIXED | MAP_PRIVATE, fd_zero, 0); + if (ptr =3D=3D MAP_FAILED) { + close(fd_zero); + ASSERT_TRUE(false); + } + ptr2 =3D mmap(&carveout[5 * page_size], 5 * page_size, + PROT_READ | PROT_WRITE, MAP_FIXED | MAP_PRIVATE, fd_zero, 0); + if (ptr2 =3D=3D MAP_FAILED) { + close(fd_zero); + ASSERT_TRUE(false); + } + close(fd_zero); + + /* Assert that they merged. */ + ASSERT_TRUE(find_vma_procmap(procmap, ptr)); + ASSERT_EQ(procmap->query.vma_start, (unsigned long)ptr); + ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr + 10 * page_size); +} + +TEST_F(merge, merge_map_private_dev_zero_faulted_unfaulted) +{ + struct procmap_fd *procmap =3D &self->procmap; + unsigned int page_size =3D self->page_size; + char *carveout =3D self->carveout; + char *ptr, *ptr2; + int fd_zero; + + if (access("/dev/zero", F_OK)) + SKIP(return, "No /dev/zero."); + fd_zero =3D open("/dev/zero", O_RDWR); + ASSERT_NE(fd_zero, -1); + + /* + * Map a MAP_PRIVATE mapping of /dev/zero with page offset 0, then fault + * it in: + * + * |-------------------------------| + * | faulted | + * |-------------------------------| + */ + ptr =3D mmap(carveout, 15 * page_size, PROT_READ | PROT_WRITE, + MAP_FIXED | MAP_PRIVATE, fd_zero, 0); + if (ptr =3D=3D MAP_FAILED) { + close(fd_zero); + ASSERT_TRUE(false); + } + memset(ptr, 'x', 15 * page_size); + + /* + * Unmap the middle: + * + * |---------| |---------| + * | faulted | | faulted | + * |---------| |---------| + */ + ASSERT_EQ(munmap(&ptr[5 * page_size], 5 * page_size), 0); + + /* + * Map in a new unfaulted mapping in the middle with page offset 0 - + * this should merge and would not if it were treated as a file rather + * than pure anon: + * + * |---------|-----------|---------| + * | faulted | unfaulted | faulted | + * |---------|-----------|---------| + */ + ptr2 =3D mmap(&carveout[5 * page_size], 5 * page_size, + PROT_READ | PROT_WRITE, MAP_FIXED | MAP_PRIVATE, + fd_zero, 0); + close(fd_zero); + ASSERT_NE(ptr2, MAP_FAILED); + + /* Assert that they merged. */ + ASSERT_TRUE(find_vma_procmap(procmap, ptr)); + ASSERT_EQ(procmap->query.vma_start, (unsigned long)ptr); + ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr + 15 * page_size); +} + TEST_F(merge_with_fork, mremap_faulted_to_unfaulted_prev) { struct procmap_fd *procmap =3D &self->procmap; --=20 2.55.0