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 A279E346AFB for ; Mon, 20 Jul 2026 19:49:04 +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=1784576946; cv=none; b=kq/vdE9P3ejIRV6up/BoE5ZS9exzwZM6KRTOsXR0vt01FWjKMKlYEOeV3yC8NUPDkvM0fzfKKvwxeEgf91OQM2ogiPCbqFEugVR+3pDmUhPrYt5erFzwsSPZS+Deeay7Tg8tYtmQTcNT+8fQQ/FtJziBTbk2oaBKS3XfgMayN7o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784576946; c=relaxed/simple; bh=1ZhICaPEjr/Ya0qjK+tBDhmXQYa00lmeveHKCRGQc+I=; h=Date:To:From:Subject:Message-Id; b=gcMW8TAIDFHzvzoBzZ9KgV/0/+BQas31ENukdECzdfrTdi/HZe2V20bCrmtTIxnprMqzgCTFqgu+2k0g1dSdixQWqYR/NxwwPw1x1T+vc4gdWfyHrELaM8HS7RqntqqkNVjWDi791kUyAJlYBjhYMy0ZtlDeEpfx4y/CyFqw7dU= 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=qA9A1yLM; 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="qA9A1yLM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7847E1F000E9; Mon, 20 Jul 2026 19:49:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1784576944; bh=OdljAooITXf5mTFo8qxz94/tCIt4+hx7DikggF8etXY=; h=Date:To:From:Subject; b=qA9A1yLMaf71Pp/SHAutLqgsNhCbQv8sONqdr/dfF/D1dGtFsYqdeQ4qNO/bwnxTi JQhq2mmCIz7EyEYDOY6BrIMLTCfWm4SZyyQgzbU2ejR/c2xY9jf+IxWzMwclZ2k9H9 ry1GZHwBgdWpz48lzuxt71ks6ZLZHpp7wrX5BN9A= Date: Mon, 20 Jul 2026 12:49:04 -0700 To: mm-commits@vger.kernel.org,ljs@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: + tools-testing-selftests-mm-test-virtual-page-offset-merge-behaviour.patch added to mm-new branch Message-Id: <20260720194904.7847E1F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: tools/testing/selftests/mm: test virtual page offset merge behaviour has been added to the -mm mm-new branch. Its filename is tools-testing-selftests-mm-test-virtual-page-offset-merge-behaviour.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/tools-testing-selftests-mm-test-virtual-page-offset-merge-behaviour.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: tools/testing/selftests/mm: test virtual page offset merge behaviour Date: Mon, 20 Jul 2026 15:38:37 +0100 While maintaining virtual 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 virtual 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 virtual page offsets. Link: https://lore.kernel.org/20260720-b4-scalable-cow-virt-pgoff-v2-11-2d549757a76f@kernel.org Signed-off-by: Lorenzo Stoakes (ARM) Cc: Alistair Popple Cc: Arnd Bergmann Cc: Baolin Wang Cc: Barry Song Cc: Byungchul Park Cc: Chengming Zhou Cc: David Hildenbrand Cc: Dev Jain Cc: Greg Kroah-Hartman Cc: Gregory Price Cc: Harry Yoo Cc: "Huang, Ying" Cc: Jan Kara Cc: Jann Horn Cc: Joshua Hahn Cc: Kees Cook Cc: Lance Yang Cc: Liam R. Howlett Cc: Matthew Brost Cc: Matthew Wilcox (Oracle) Cc: Miaohe Lin Cc: Michal Hocko Cc: Mike Rapoport Cc: Naoya Horiguchi Cc: Nico Pache Cc: Pedro Falcato Cc: Peter Xu Cc: Rakie Kim Cc: Rik van Riel Cc: Ryan Roberts Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: xu xin Cc: Zi Yan Signed-off-by: Andrew Morton --- tools/testing/selftests/mm/merge.c | 57 +++++++++++++++++++++++++++ 1 file changed, 57 insertions(+) --- a/tools/testing/selftests/mm/merge.c~tools-testing-selftests-mm-test-virtual-page-offset-merge-behaviour +++ a/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); } +TEST_F(merge, virt_and_page_offset_mismatch_memfd) +{ + struct procmap_fd *procmap = &self->procmap; + unsigned int page_size = self->page_size; + char *carveout = self->carveout; + char *ptr, *ptr2; + int fd; + + /* Create a 10 page memfd descriptor. */ + fd = memfd_create("virt_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 = 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 = 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] = 'x'; + + /* + * Now move it in place: + * + * |----------| + * | | + * v | + * |-----------| |---------| + * | unfaulted | | faulted | + * |-----------| |---------| + * + * Because virtual 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 virtual page + * offset. + */ + ptr2 = 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 = &self->procmap; _ Patches currently in -mm which might be from ljs@kernel.org are mm-vmalloc-acquire-init_mm-lock-on-huge-vmap-to-avoid-ptdump-uaf.patch x86-mm-pat-acquire-init_mm-write-lock-on-collapse-to-avoid-uaf.patch x86-mm-pat-acquire-init_mm-read-lock-on-attribute-change-to-avoid-uaf.patch mm-ptdump-always-stabilise-against-page-table-freeing-using-init_mm.patch arm64-remove-redundant-concurrent-ptdump-uaf-mitigation.patch mm-move-alloc-tag-to-mm.patch mm-move-vma_start_pgoff-into-mmh-and-clean-up.patch mm-add-kdoc-comments-for-vma_start-last_pgoff.patch tools-testing-vma-use-vma_start_pgoff-in-merge-tests.patch mm-introduce-and-use-vma_end_pgoff.patch mm-rmap-update-mm-interval_treec-comments.patch mm-rmap-parameterise-vma_interval_tree_-by-address_space.patch mm-rmap-elide-unnecessary-static-inlines-in-interval_treec.patch mm-rmap-rename-vma_interval_tree_-to-mapping_rmap_tree_.patch mm-rmap-parameterise-anon_vma_interval_tree_-by-anon_vma.patch mm-rmap-rename-anon_vma_interval_tree_-params-and-use-pgoff_t.patch mm-rmap-rename-anon_vma_interval_tree_-to-anon_rmap_tree_.patch maintainers-move-mm-interval_treec-to-rmap-section.patch mm-vma-introduce-and-use-vmg_pages-vmg__pgoff.patch mm-vma-clean-up-anon_vma_compatible.patch mm-vma-refactor-vmg_adjust_set_range-for-clarity.patch mm-vma-minor-cleanup-of-expand_.patch mm-introduce-and-use-linear_page_delta.patch mm-vma-use-vma_start_pgoff-linear_page_index-in-mm-code.patch mm-prefer-vma__pgoff-to-vma-vm_pgoff-in-kernel.patch mm-vma-remove-duplicative-vma_pgoff_offset-helper.patch mm-use-linear_page_-consistently.patch mm-vma-introduce-vma_assert_can_modify.patch mm-vma-add-and-use-vma__pgoff.patch mm-vma-move-__install_special_mapping-to-vmac.patch mm-vma-make-vma_set_range-static-drop-insert_vm_struct-decl.patch mm-vma-update-vma_shrink-to-not-pass-start-pgoff-parameters.patch mm-vma-update-vmg_adjust_set_range-to-offset-pgoff-instead.patch mm-vma-slightly-rework-the-anonymous-check-in-__mmap_new_vma.patch mm-vma-introduce-and-use-vma_set_pgoff.patch mm-vma-correct-incorrect-vmah-inclusion.patch mm-vma-use-guard-clauses-in-can_vma_merge_.patch tools-testing-vma-default-vma-mm-flag-bits-to-64-bit.patch tools-testing-vma-output-compared-expression-on-assert_.patch mm-introduce-vma_flags_can_grow-and-vma_can_grow.patch mm-vma-update-do_mmap-to-use-vma_flags_t.patch mm-convert-__get_unmapped_area-to-use-vma_flags_t.patch mm-update-generic_get_unmapped_area-to-use-vma_flags_t.patch mm-prefer-mm-def_vma_flags-in-mm-logic.patch mm-vma-convert-vm_pgprot_modify-to-use-vma_flags_t-and-rename.patch mm-vma-rename-vma_get_page_prot-to-vma_flags_to_page_prot.patch mm-introduce-vma_get_page_prot-and-use-it.patch mm-vma-update-create_init_stack_vma-to-use-vma_flags_t.patch mm-vma-convert-miscellaneous-uses-of-vma-flags-in-core-mm.patch mm-mlock-convert-mlock-code-to-use-vma_flags_t.patch mm-mprotect-convert-mprotect-code-to-use-vma_flags_t.patch mm-mremap-convert-mremap-code-to-use-vma_flags_t.patch mm-mseal-remove-superfluous-comments-fix-confusion-around-mm.patch mm-mseal-limit-scope-of-mseal-address-zero-to-address-zero.patch mm-mseal-remove-further-superfluous-comments-do_mseal.patch mm-vma-introduce-vma-virtual-page-offset-field-and-add-helpers.patch mm-introduce-linear_virt_page_index.patch mm-abstract-vma_address-and-introduce-vma_anon_address.patch mm-update-print_bad_page_map-to-show-virtual-page-index.patch mm-introduce-and-use-vma_filebacked_address.patch mm-propagate-vma-virtual-page-offset-on-map-remap-split-merge.patch mm-rmap-track-whether-the-page-vma-mapped-walk-is-anonymous.patch mm-introduce-and-use-linear_folio_page_index.patch mm-rmap-use-virt-pgoff-for-map_private-file-backed-anon-folios.patch tools-testing-vma-expand-vma-merge-tests-to-assert-virt-pgoff.patch tools-testing-selftests-mm-test-virtual-page-offset-merge-behaviour.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