From mboxrd@z Thu Jan 1 00:00:00 1970 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 1EC9C37BE89 for ; Sat, 10 Oct 2026 22:03:05 +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=1791669786; cv=none; b=WMMiqZChcZw3aJU1G6FAuLlvMIQENAVjJfF307zmjk07P9OMXtefKfa/l9gyHyz9+zrkGs0BpBVAt8yOtcwSc/IogNpe7Pb8qz0QLOZdObkOnIaWL0JydnDk8y1aHH1ot2E0nsNBUnG3RWRHdCY4zi5biN5bIqoXpRL5BPyUgok= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791669786; c=relaxed/simple; bh=rElbMAvGKJPrcm0lR7i32ikL7wHmt4XECeOwiWjGwFQ=; h=Date:To:From:Subject:Message-Id; b=aBZQoVEqdMeLgTuLDaqLrDHPP8bBwXVuTaFawLhxgjRSAkBH9iiNArJNrrsNqF3yO86bQd2lb04s4XSOwKxKs3r0HfToU8mmg7rEFgADtQVk9atTvxMf3T/v/67dReFRuX5kg1aHLMiQU9qyS0WmaJSbc5OXVpWeZ0zSNk2BHLc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=Gy+1wI5U; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="Gy+1wI5U" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E67501F000FF; Sat, 10 Oct 2026 22:03:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1791669785; bh=nVMuxc4Gp4RCXv/AIPTlZnKnkd80UJWlfpIexJ3uviY=; h=Date:To:From:Subject; b=Gy+1wI5UQqpe4T6LMUYf2WRjIxhxMe0aXPEwpuv5F9J+RFsF9Wz9rSMrc2RVuMlSf BR9G+5UsGCQi+vxlDpv+ZVJvhS+SjOBnFd8QkxVUncVRX+cRXZ+5ILaRXS/SG1WvT8 itAXCE92VRbxyJrD1qYALkeKFGQC3SjaHWdz2KNc= Date: Sat, 10 Oct 2026 15:03:04 -0700 To: mm-commits@vger.kernel.org,ljs@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-vma-introduce-vma_is_mm_backed.patch added to mm-unstable branch Message-Id: <20261010220304.E67501F000FF@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm/vma: introduce vma[_flags]_is_mm_backed() has been added to the -mm mm-unstable branch. Its filename is mm-vma-introduce-vma_is_mm_backed.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-vma-introduce-vma_is_mm_backed.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: "Lorenzo Stoakes (ARM)" Subject: mm/vma: introduce vma[_flags]_is_mm_backed() Date: Fri, 09 Oct 2026 19:04:24 +0100 Introduce vma[_flags]_is_mm_backed() for the purposes of identifying mappings which are mm-managed and whose contents were placed there by core mm's own fault path - rather than a custom ->fault handler - and which core mm has not reserved the right to discard. Mappings not managed by core mm do not fall into this category, as they are populated by their owner, and nor of course does memory-mapped I/O. We exclude fixed mappings as these have a layout core mm cannot assume ordinary fault semantics over. hugetlb mappings are fixed mappings, but core mm owns them entirely, so they are explicitly carved out as mm-backed, as the MADV_DODUMP check already does. Droppable mappings are excluded as core mm has promised it may discard them at any time. Use this functionality to update the madvise MADV_DODUMP check to test for this rather than open-coding it. This replaces the VM_SPECIAL check which means it no longer checks for VMA_IO_BIT, however this is safe as we have established the invariant that mm-managed mappings may not set VMA_IO_BIT, so we implicitly include these. No functional change intended. Link: https://lore.kernel.org/20261009-b4-mmap-prepare-vma-flag-sanify-v5-30-923b70125b1e@kernel.org Signed-off-by: Lorenzo Stoakes (ARM) Signed-off-by: Andrew Morton Acked-by: Zi Yan Cc: Liam R. Howlett Cc: Vlastimil Babka Cc: Jann Horn Cc: Pedro Falcato Cc: David Hildenbrand Cc: Mike Rapoport Cc: Suren Baghdasaryan Cc: Michal Hocko Cc: Jonathan Corbet Cc: Greg Kroah-Hartman Cc: Dennis Dalessandro Cc: Jason Gunthorpe Cc: Leon Romanovsky Cc: Paul Moore Cc: Stephen Smalley Cc: Jaroslav Kysela Cc: Takashi Iwai Cc: Alexei Starovoitov Cc: Daniel Borkmann Cc: Andrii Nakryiko Cc: Eduard Zingerman Cc: Kumar Kartikeya Dwivedi Cc: Baolin Wang Cc: Nico Pache Cc: Ryan Roberts Cc: Dev Jain Cc: Barry Song Cc: Lance Yang Cc: Usama Arif Cc: Kiryl Shutsemau Cc: Doug Gilbert Cc: James Bottomley Cc: Martin K. Petersen Cc: Simona Vetter Cc: Helge Deller Cc: Sebastian Reichel Cc: John Hubbard Cc: Peter Xu Cc: Masami Hiramatsu Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: Arnaldo Carvalho de Melo Cc: Namhyung Kim Cc: Mark Rutland Cc: Rik van Riel Cc: Harry Yoo Cc: Juri Lelli Cc: Vincent Guittot Cc: Maarten Lankhorst Cc: Maxime Ripard Cc: Thomas Zimmermann Cc: David Airlie Cc: Will Deacon Cc: Aneesh Kumar K.V Cc: Nicholas Piggin Cc: Arnd Bergmann Cc: Muchun Song Cc: Oscar Salvador Cc: Matthew Wilcox (Oracle) Cc: Jan Kara Cc: Marc Zyngier Cc: Oliver Upton Cc: Catalin Marinas Cc: Madhavan Srinivasan Cc: Anup Patel Cc: Paul Walmsley Cc: Palmer Dabbelt Cc: Albert Ou Cc: Christian Borntraeger Cc: Janosch Frank Cc: Claudio Imbrenda Cc: Alexander Gordeev Cc: Gerald Schaefer Cc: Heiko Carstens Cc: Vasily Gorbik Cc: David S. Miller Cc: Andreas Larsson Cc: Al Viro Cc: Christian Brauner Cc: Matthew Brost Cc: Joshua Hahn Cc: Rakie Kim Cc: Byungchul Park Cc: Gregory Price Cc: Ying Huang Cc: Alistair Popple Cc: Chris Li Cc: Kairui Song Cc: Kemeng Shi Cc: Nhat Pham Cc: Baoquan He Cc: Youngjun Park Cc: Johannes Weiner Cc: Qi Zheng Cc: Shakeel Butt Cc: Axel Rasmussen Cc: Yuanchu Xie Cc: Wei Xu Cc: Chengming Zhou Cc: Michal Hocko Cc: Miklos Szeredi Cc: Xu Xin Cc: Ihor Solodrai Cc: Bert Karwatzki --- include/linux/mm.h | 50 +++++++++++++++++++++++++++++++++++++++++++ mm/madvise.c | 4 +-- 2 files changed, 52 insertions(+), 2 deletions(-) --- a/include/linux/mm.h~mm-vma-introduce-vma_is_mm_backed +++ a/include/linux/mm.h @@ -1740,6 +1740,56 @@ static inline bool vma_can_merge(const s } /** + * vma_flags_is_mm_backed() - Do the specified VMA flags imply the mapping is + * backed by core mm? + * @flags: The VMA flags to test. + * + * An mm-backed mapping is one managed by core mm (see + * vma_flags_is_mm_managed()) for which two further things are true: + * + * 1. Everything mapped was placed there by core mm's fault path (no custom + * ->fault). + * 2. What is mapped stays there until it is zapped or unmapped by the user. + * + * These mappings are the only ones which can be sensibly locked, merged, dumped + * or be subject to uffd faulting, as all of these assume core mm and core mm + * alone manages these, and that the mappings will remain there. + * + * Returns: true if the flags imply an mm-backed mapping, otherwise false. + */ +static inline bool vma_flags_is_mm_backed(const vma_flags_t *flags) +{ + /* hugetlb is a fixed mapping, but core mm owns it entirely. */ + if (vma_flags_is_hugetlb(flags)) + return true; + /* + * Mappings not managed by core mm are populated by their owner. + * + * Fixed mappings may be mm-managed, but their contents are established + * by a custom ->fault handler, so core mm cannot assume ordinary fault + * semantics over them. + */ + if (!vma_flags_is_mm_managed(flags) || + vma_flags_is_fixed_mapping(flags)) + return false; + /* Core mm may discard droppable memory at any time. */ + return !vma_flags_test_single_mask(flags, VMA_DROPPABLE); +} + +/** + * vma_is_mm_backed() - Is @vma backed by core mm? + * @vma: The VMA to test. + * + * See vma_flags_is_mm_backed() for details. + * + * Returns: true if the VMA is mm-backed, otherwise false. + */ +static inline bool vma_is_mm_backed(const struct vm_area_struct *vma) +{ + return vma_flags_is_mm_backed(&vma->flags); +} + +/** * vma_kernel_pagesize - Default page size granularity for this VMA. * @vma: The user mapping. * --- a/mm/madvise.c~mm-vma-introduce-vma_is_mm_backed +++ a/mm/madvise.c @@ -1421,8 +1421,8 @@ static int madvise_vma_behavior(struct m new_flags |= VM_DONTDUMP; break; case MADV_DODUMP: - if ((!vma_is_hugetlb(vma) && (new_flags & VM_SPECIAL)) || - (new_flags & VM_DROPPABLE)) + /* Only mm-backed memory can be meaningfully dumped. */ + if (!vma_is_mm_backed(vma)) return -EINVAL; new_flags &= ~VM_DONTDUMP; break; _ Patches currently in -mm which might be from ljs@kernel.org are mm-vma-fix-mmap_prepare-file-handling-remove-file_doesnt_need_get.patch mm-vma-introduce-and-use-vma_can_merge.patch mm-consistently-validate-vma-state-after-mmap-hooks.patch mm-vma-ensure-mmap_prepare-doesnt-set-actions-on-a-mergeable-vma.patch mm-make-map_kernel_pages_-internal-and-unexported.patch mm-vma-tidy-up-map-kernel-pages-enum-values.patch mm-add-mmap-action-for-discontiguous-kernel-page-mapping.patch docs-filesystems-update-mmap_prepare-docs-for-discontig-kernel-pgs.patch drivers-usb-mon-update-to-use-mmap_prepare-map-kernel-pages.patch infiniband-update-hfi1-to-use-remap_vmalloc_range.patch selinux-reject-writable-opens-of-policy-file-drop-mmap-shared-write-check.patch alsa-pcm-use-vm_insert_page-to-map-pcm-status-page.patch bpf-arena-mark-arena_map_mmap-mappings-vm_mixedmap.patch mm-vma-add-vma_is_mm_managed-predicates.patch mm-vma-only-allow-mmap-to-clear-vma_maywrite_bit-if-not-mm-managed.patch mm-vma-add-and-use-vma__is_fixed_mapping.patch scsi-sg-convert-mmap-hook-to-mmap_prepare-and-rework.patch fbdev-defio-assert-fbinfo_virtfb-drop-vm_io-add-vm_mixedmap.patch hsi-cmt_speech-convert-mmap-hook-to-mmap_prepare-refactor.patch mm-gup-error-out-early-on-vma_mayread_bit-vmas.patch uprobes-remove-vm_io-set-vm_mixedmap-for-mapped-kernel-pages.patch mm-mlock-clear-vma_locked_mask-over-mmap-callback.patch mm-mlock-eliminate-weird-vma_io_bit-abuse-and-simplify.patch mm-vma-enforce-that-mm-managed-mappings-may-not-set-vma_io_bit.patch mm-remove-vma_io_bit-check-in-vma_is_mm_managed.patch mm-remove-hugetlb_inlineh.patch mm-rename-is_vm_hugetlb_page-to-vma_is_hugetlb.patch mm-drop-some-redundant-checks-around-hugetlb-vmas.patch mm-madvise-update-is_valid_guard_vma-to-use-vma_can_merge.patch mm-vma-introduce-vma_is_mm_backed.patch mm-uffd-use-predicates-for-userfaultfd-checks.patch mm-madvise-use-predicates-for-madvise-madv_dofork.patch mm-eliminate-vma_special_flags-usage-when-hugetlb-explicitly-tested.patch mm-eliminate-vma_special_flags-check-in-lru_gen_look_around.patch mm-avoid-use-of-vma_special_flags-in-migrate_vma_setup.patch mm-eliminate-vm_special-vma_special_flags.patch fuse-dax-do-not-set-vm_mixedmap.patch mm-huge_memory-remove-vma_is_special_huge.patch mm-vma-const-ify-vma_assert_stabilised-and-associated-functions.patch mm-implement-and-use-vma_has_anon_rmap-silence-kcsan.patch mm-update-comments-to-refer-to-anon-rmap-rather-than-anon_vma.patch mm-vma-dont-remove-vma-from-rmap-if-pgoff-unchanged.patch