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 9A22D135A53 for ; Tue, 15 Sep 2026 01:10:08 +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=1789434613; cv=none; b=d4J3hOS/O5HLySCkA1JLAJtjYPqbgBSFCgTjER5B69iVewg7KHu/OeXp7hS4x/6GudwNcLSNHMyC1uDlOU5V89qH8jWwkiKvelS6Ye9KXTyWXIlMgKFyYV02aIQNeQpiiC6aPQnH+HRplEjsj+0jMa9a+QzD9QisnK11QcljveY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789434613; c=relaxed/simple; bh=/rZdeAxmqg0wavHZ2y6fzTZzTOnV7ErlCLD2C57rAJU=; h=Date:To:From:Subject:Message-Id; b=eZ8O3eeYYjMkMfd1Kz4BTHN1K9mURVe/sKwPl0PalAGcuDcGWYLmCI31wgsveeyjZiqYl/tV0zzhv0DN62xM/V6blRO7wlbJ4ZFpIG3PkZ70HiLltY+amvLsV8Tuj4IO7GeqaM+pm+0pdEXE281ss1LEWZUEl6GBZiXff0Iyld8= 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=SMdBmNxt; 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="SMdBmNxt" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DCF521F00893; Tue, 15 Sep 2026 01:10:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1789434608; bh=+/7mStU9ecsS8+O8FuzP4kjn9Sn6nNTYYQyhf2ubg2g=; h=Date:To:From:Subject; b=SMdBmNxtPq+6i8E12XaXNK1kbbgwDNET2f5mIlFJjtk96wiWybKD9GThfDIn05583 urelcwF+EsQoOYZb+mWzCMegQQ/RSODoS6eHlbZ7B1rWJQbtn374pzcDSYGx23hc+K fI9ZDVybEbddBuxF7Cjm/IQt8qOl88tp0lMIefQw= Date: Mon, 14 Sep 2026 18:10:07 -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-new branch Message-Id: <20260915011007.DCF521F00893@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-new 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-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new. The mm-new branch of mm.git is not included in linux-next If a few days of testing in mm-new is successful, the patch will me moved into mm.git's mm-unstable branch, which is included in linux-next 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: Mon, 14 Sep 2026 15:57:53 +0100 Make it clear what we're blocking in MADV_DOFORK. Previously we simply disallowed VM_SPECIAL i.e. kernel-owned mappings, fixed mappings and VMA_IO_BIT. Now the invariant is established that only kernel-owned mappings can set VMA_IO_BIT, the VMA_IO_BIT check is redundant. The rest is equivalent to testing for a kernel-owned or fixed 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/20260914-b4-mmap-prepare-vma-flag-sanify-v2-33-7d9781ed5361@kernel.org Signed-off-by: Lorenzo Stoakes (ARM) Signed-off-by: Andrew Morton --- 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 @@ -1565,7 +1565,7 @@ 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-vmpressure-remove-window-size-todo.patch tools-testing-selftests-mm-add-missing-gitignore-entries.patch mm-move-drivers-char-memc-to-mm-char-memc.patch mm-implement-file_is_dev_zero-to-uniquely-identify-dev-zero.patch mm-vma-only-permit-map_private-dev-zero-to-be-mapped-anonymous.patch mm-vma-make-map_private-mapped-dev-zero-mappings-truly-anonymous.patch tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon.patch tools-testing-selftests-mm-add-map_private-dev-zero-merge-tests.patch mm-madvise-swap-in-cowd-map_private-file-mappings-on-madv_willneed.patch mm-huge_memory-zap-deposited-page-tables-after-an-rcu-grace-period.patch mm-enable-mmu_gather_rcu_table_free-for-most-2-level-architectures.patch mm-enable-mmu_gather_rcu_table_free-for-mmu-riscv.patch mm-enable-mmu_gather_rcu_table_free-for-mmu-arm.patch mm-enable-mmu_gather_rcu_table_free-for-arc-microblaze-xtensa.patch mm-enable-mmu_gather_rcu_table_free-for-sparc64.patch mm-enable-mmu_gather_rcu_table_free-for-m68k-coldfire.patch mm-enable-mmu_gather_rcu_table_free-for-sh-x2.patch mm-enable-mmu_gather_rcu_table_free-for-m68k-motorola.patch mm-enable-mmu_gather_rcu_table_free-for-sparc32.patch mm-make-userland-page-table-freeing-rcu-safe.patch mm-change-the-contract-for-free_pgtables-update-docs.patch mm-vma-fix-mmap_prepare-file-handling-remove-file_doesnt_need_get.patch mm-vma-predicate-setting-mmap_prepare-vma-fields-on-new-vma-alloc.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_kernel_owned-predicates.patch mm-vma-only-allow-mmap-to-clear-vma_maywrite_bit-if-kernel-owned.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-only-kernel-owned-mappings-may-set-vma_io_bit.patch mm-remove-vma_io_bit-check-in-vma_is_kernel_owned.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_persistent.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-introduce-and-use-vma_can_gup.patch