From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 2874A266576 for ; Thu, 19 Mar 2026 22:17:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773958622; cv=none; b=hboYyf7ViYZV/GjcH0zy2chi8yt2FiwwX8jN42IG+u+Z/4+ZDRrowA249YPuVrNaUToOph/WtnBuj8cZo+E5wJcxqmL6uj+r0oe4lx0W3Oo7+WRDXVCCZ6ND0kK2nrpwgxbIC2Bhr0Q2IWk3wur4SVj/Zm2ywGr/nd/3T3nq2mY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773958622; c=relaxed/simple; bh=gPD8pVAnB0LJq93J9eefSn5nPY0L2SjN/mvD4ajlHCQ=; h=Date:To:From:Subject:Message-Id; b=VVcjG777CbwFcniKXtZsnoD1NMfggF8YNGDqIXWkZU5WDh3giiVZX8NoN6P6jm/qbEtdOXVUIjPEgcrcD1VQHS7lP/65+i/kSKs5SB6u3NwG7GjFuztssyTCV4hdprzesyrhv3/Os+po0/OOqQ9sh/f+10lW75W/qJxzmRjgDfo= 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=lX8Mvntv; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="lX8Mvntv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B2660C19424; Thu, 19 Mar 2026 22:17:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1773958621; bh=gPD8pVAnB0LJq93J9eefSn5nPY0L2SjN/mvD4ajlHCQ=; h=Date:To:From:Subject:From; b=lX8MvntvoO7EhZh8vPhxU4Ptm7LB+o4pTgniO5Pm8KVXSz7iWSKbrA4KS8DpvXkNl JoHaYahAQnS25bE96pfUBrHQLb7CT1hjhrnM8EApqBoPur7qPZLmbKikgwy6xMOZx8 3crV4MTtm9gNL7tihzsMfiUHnFEdby68CZyrgRqI= Date: Thu, 19 Mar 2026 15:17:01 -0700 To: mm-commits@vger.kernel.org,ziy@nvidia.com,zhengqi.arch@bytedance.com,surenb@google.com,ryan.roberts@arm.com,rppt@kernel.org,npache@redhat.com,mhocko@suse.com,liam.howlett@oracle.com,lance.yang@linux.dev,kirill@shutemov.name,dev.jain@arm.com,david@kernel.org,baolin.wang@linux.alibaba.com,baohua@kernel.org,ljs@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-huge_memory-handle-buggy-pmd-entry-in-zap_huge_pmd.patch added to mm-new branch Message-Id: <20260319221701.B2660C19424@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm/huge_memory: handle buggy PMD entry in zap_huge_pmd() has been added to the -mm mm-new branch. Its filename is mm-huge_memory-handle-buggy-pmd-entry-in-zap_huge_pmd.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-huge_memory-handle-buggy-pmd-entry-in-zap_huge_pmd.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 (Oracle)" Subject: mm/huge_memory: handle buggy PMD entry in zap_huge_pmd() Date: Thu, 19 Mar 2026 13:00:10 +0000 A recent bug I analysed [0] managed to, through a bug in the userfaultfd implementation, reach an invalid point in the zap_huge_pmd() code where the PMD was none of: - A non-DAX, PFN or mixed map. - The huge zero folio - A present PMD entry - A softleaf entry The code at this point calls folio_test_anon() on a known-NULL folio. Having logic like this explicitly NULL dereference in the code is hard to understand, and makes debugging potentially more difficult. Add an else branch to handle this case and WARN(). Link: https://lkml.kernel.org/r/1ec18767b106a1ee1ed6e33e332c3ad5531dc636.1773924928.git.ljs@kernel.org Link: https://lore.kernel.org/all/6b3d7ad7-49e1-407a-903d-3103704160d8@lucifer.local/ [1] Signed-off-by: Lorenzo Stoakes (Oracle) Cc: Baolin Wang Cc: Barry Song Cc: David Hildenbrand (ARM) Cc: Dev Jain Cc: Lance Yang Cc: Liam Howlett Cc: Michal Hocko Cc: Mike Rapoport Cc: Nico Pache Cc: Qi Zheng Cc: Ryan Roberts Cc: Suren Baghdasaryan Cc: Zi Yan Cc: Kiryl Shutsemau Signed-off-by: Andrew Morton --- mm/huge_memory.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/mm/huge_memory.c~mm-huge_memory-handle-buggy-pmd-entry-in-zap_huge_pmd +++ a/mm/huge_memory.c @@ -2385,6 +2385,10 @@ bool zap_huge_pmd(struct mmu_gather *tlb if (!thp_migration_supported()) WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); + } else { + WARN_ON_ONCE(true); + spin_unlock(ptl); + return true; } if (folio_test_anon(folio)) { _ Patches currently in -mm which might be from ljs@kernel.org are mm-zswap-add-missing-kunmap_local.patch mm-rmap-clear-vma-anon_vma-on-error.patch mm-rename-vma-flag-helpers-to-be-more-readable.patch mm-add-vma_desc_test_all-and-use-it.patch mm-always-inline-__mk_vma_flags-and-invoked-functions.patch mm-reintroduce-vma_flags_test-as-a-singular-flag-test.patch mm-reintroduce-vma_desc_test-as-a-singular-flag-test.patch tools-testing-vma-add-test-for-vma_flags_test-vma_desc_test.patch tools-testing-vma-add-test-for-vma_flags_test-vma_desc_test-fix.patch mm-mremap-correct-invalid-map-count-check.patch mm-abstract-reading-sysctl_max_map_count-and-read_once.patch mm-mremap-check-map-count-under-mmap-write-lock-and-abstract.patch mm-vma-add-vma_flags_empty-vma_flags_and-vma_flags_diff_pair.patch tools-testing-vma-add-unit-tests-flag-empty-diff_pair-and.patch mm-vma-add-further-vma_flags_t-unions.patch tools-testing-vma-convert-bulk-of-test-code-to-vma_flags_t.patch mm-vma-use-new-vma-flags-for-sticky-flags-logic.patch tools-testing-vma-fix-vma-flag-tests.patch mm-vma-add-append_vma_flags-helper.patch tools-testing-vma-add-simple-test-for-append_vma_flags.patch mm-unexport-vm_brk_flags-and-eliminate-vm_flags-parameter.patch mm-vma-introduce-vma_flags_same.patch mm-vma-introduce-_to_-helpers.patch tools-testing-vma-test-that-legacy-flag-helpers-work-correctly.patch mm-vma-introduce-vma_test-and-make-inlining-consistent.patch tools-testing-vma-update-vma-flag-tests-to-test-vma_test.patch mm-introduce-vma_flags_count-and-vma_test_single_mask.patch tools-testing-vma-test-vma_flags_countvma_test_single_mask.patch mm-convert-do_brk_flags-to-use-vma_flags_t.patch mm-update-vma_supports_mlock-to-use-new-vma-flags.patch mm-vma-introduce-vma_clear_flags.patch tools-testing-vma-update-vma-tests-to-test-vma_clear_flags.patch mm-vma-convert-as-much-as-we-can-in-mm-vmac-to-vma_flags_t.patch mm-vma-convert-vma_modify_flags-to-use-vma_flags_t.patch mm-vma-convert-__mmap_region-to-use-vma_flags_t.patch mm-various-small-mmap_prepare-cleanups.patch mm-add-documentation-for-the-mmap_prepare-file-operation-callback.patch mm-document-vm_operations_struct-open-the-same-as-close.patch mm-add-vm_ops-mapped-hook.patch fs-afs-correctly-drop-reference-count-on-mapping-failure.patch mm-add-mmap_action_simple_ioremap.patch misc-open-dice-replace-deprecated-mmap-hook-with-mmap_prepare.patch hpet-replace-deprecated-mmap-hook-with-mmap_prepare.patch mtdchar-replace-deprecated-mmap-hook-with-mmap_prepare-clean-up.patch stm-replace-deprecated-mmap-hook-with-mmap_prepare.patch staging-vme_user-replace-deprecated-mmap-hook-with-mmap_prepare.patch mm-allow-handling-of-stacked-mmap_prepare-hooks-in-more-drivers.patch drivers-hv-vmbus-replace-deprecated-mmap-hook-with-mmap_prepare.patch uio-replace-deprecated-mmap-hook-with-mmap_prepare-in-uio_info.patch mm-add-mmap_action_map_kernel_pages.patch mm-on-remap-assert-that-input-range-within-the-proposed-vma.patch mm-huge_memory-simplify-vma_is_specal_huge.patch mm-huge-avoid-big-else-branch-in-zap_huge_pmd.patch mm-huge_memory-have-zap_huge_pmd-return-a-boolean-add-kdoc.patch mm-huge_memory-handle-buggy-pmd-entry-in-zap_huge_pmd.patch mm-huge_memory-add-a-common-exit-path-to-zap_huge_pmd.patch mm-huge_memory-remove-unnecessary-vm_bug_on_page.patch mm-huge_memory-deduplicate-zap-deposited-table-call.patch mm-huge_memory-deduplicate-zap_huge_pmd-further-by-tracking-state.patch mm-huge_memory-have-zap_huge_pmd-use-vm_normal_folio_pmd.patch