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 A4E6B37F73A for ; Sat, 10 Oct 2026 22:03:09 +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=1791669792; cv=none; b=pBSmzif4d+MjNNjU0z8i75tpcSN7GFn3fUJL7xg/6FcfiOAncmRx1Zv+y0wWWRB5yV55CYPxWpEb5v34ZP3FDEE1MOHpWjjFwFRgRnBTQ54hYMHNuNd0fVqyTVWTUMGj4GOFhBCoARTxsu1vh1F2m2KcoCErsrYT3wLH6dch8fU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791669792; c=relaxed/simple; bh=vSXfI/U8R+T94PbqXRL7N7G90d4Z6fG1WYivkOQy9gM=; h=Date:To:From:Subject:Message-Id; b=nAWEgdEzov4K4dW3/4TlckoUHhl8hwPebmtBbi5k6KSmsRgvNTzolE+G2yh1VaiM7l066e3iczCTLLdgd/G4y3DJ8BtkjTzDt1pBlKJsQDC1yk8CBawTykv+lDGsjeteP8D5gVWqs73+ogRzOCLLo2WPop1Bq4TdaaCsDPF6TJQ= 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=K0BgIx4t; 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="K0BgIx4t" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6EC481F000FF; Sat, 10 Oct 2026 22:03:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1791669789; bh=zeCoVvG+3INFtM9flaTsH5Cso9yBGYnUDSKy1Kx4vQQ=; h=Date:To:From:Subject; b=K0BgIx4tBqHfoY4GamSumKrsGfhQT6oO2KlDhWVIwL60eBdG0qHDptnoEyKODR9AL yB/lknFu/YZpUFQF/YEof+A6C2WyLfvkXU+pkobPeId03gSn6jQ1DNMuvBP1TfZaDb l7K2HUU0wqHdqy14fEGjaEjmvfSuufstnQrxKHe4= Date: Sat, 10 Oct 2026 15:03:09 -0700 To: mm-commits@vger.kernel.org,ljs@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-madvise-use-predicates-for-madvise-madv_dofork.patch added to mm-unstable branch Message-Id: <20261010220309.6EC481F000FF@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm/madvise: use predicates for madvise(..., MADV_DOFORK) has been added to the -mm mm-unstable branch. Its filename is mm-madvise-use-predicates-for-madvise-madv_dofork.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-madvise-use-predicates-for-madvise-madv_dofork.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/madvise: use predicates for madvise(..., MADV_DOFORK) Date: Fri, 09 Oct 2026 19:04:26 +0100 Make it clear what we're blocking in MADV_DOFORK. Previously we simply disallowed VM_SPECIAL i.e. mappings not managed by core mm, fixed mappings and VMA_IO_BIT. Now the invariant is established that mm-managed mappings may not set VMA_IO_BIT, the VMA_IO_BIT check is redundant. The rest is equivalent to testing for a fixed or non-mm-managed mapping, i.e. exactly the same check as whether the VMA is permitted to be merged. This was established by commit 0b2758f48f22 ("Require (reasonably) normal mappings for MADV_DOFORK") containing my hands-down favourite call out of all time. Express the same thing differently - if we wouldn't be allowed to merge it, then we aren't allowed to manipulate CoW behaviour on fork. No functional change intended. Link: https://lore.kernel.org/20261009-b4-mmap-prepare-vma-flag-sanify-v5-32-923b70125b1e@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 --- mm/madvise.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/madvise.c~mm-madvise-use-predicates-for-madvise-madv_dofork +++ a/mm/madvise.c @@ -1402,7 +1402,7 @@ static int madvise_vma_behavior(struct m new_flags |= VM_DONTCOPY; break; case MADV_DOFORK: - if (new_flags & VM_SPECIAL) + if (!vma_can_merge(vma)) return -EINVAL; new_flags &= ~VM_DONTCOPY; 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