+ mm-hugetlb-tolerate-uffd_wp-markers-outside-uffd-wp-vmas.patch added to mm-hotfixes-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm/hugetlb: tolerate UFFD_WP markers outside uffd-wp VMAs
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-hugetlb-tolerate-uffd_wp-markers-outside-uffd-wp-vmas.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-hugetlb-tolerate-uffd_wp-markers-outside-uffd-wp-vmas.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: "David Hildenbrand (Arm)" <david@kernel.org>
Subject: mm/hugetlb: tolerate UFFD_WP markers outside uffd-wp VMAs
Date: Thu, 15 Oct 2026 18:07:14 +0200

UFFD PTE bit handling is a bit like swiss cheese, in particular with
recently added RWP mode. Having uffd-wp markers outside uffd-wp VMAs
already confused this code in the past and resulted in uffd-pte bits
confusing other code later.

Let's play safe and just ignore these markers in hugetlb_no_page(), not
silently propagating the uffd-wp PTE bit.

Link: https://lore.kernel.org/20261015-urgent_fixes-v1-8-42796911043b@kernel.org
Fixes: 2d427bb01639 ("mm/userfaultfd: add RWP fault delivery and expose UFFDIO_REGISTER_MODE_RWP")
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Adam Litke <agl@us.ibm.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Rik van Riel <riel@surriel.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Kiryl Shutsemau <kas@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: <stable@vger.kernel.org>
---

 mm/hugetlb.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/mm/hugetlb.c~mm-hugetlb-tolerate-uffd_wp-markers-outside-uffd-wp-vmas
+++ a/mm/hugetlb.c
@@ -5950,8 +5950,11 @@ static vm_fault_t hugetlb_no_page(struct
 	/*
 	 * If this pte was previously wr-protected, keep it wr-protected even
 	 * if populated.
+	 *
+	 * TODO: fix all cases where uffd-wp markers remain in VMAs that are no
+	 * longer registered with uffd.
 	 */
-	if (unlikely(pte_is_uffd_wp_marker(vmf->orig_pte)))
+	if (unlikely(userfaultfd_wp(vma) && pte_is_uffd_wp_marker(vmf->orig_pte)))
 		new_pte = huge_pte_mkuffd(new_pte);
 	set_huge_pte_at(mm, vmf->address, vmf->pte, new_pte, huge_page_size(h));
 
_

Patches currently in -mm which might be from david@kernel.org are

mm-fix-address-wraparound-when-scanning-large-folio-ptes.patch
mm-hugetlb-fix-use-after-free-in-hugetlb_mfill_atomic_pte.patch
mm-hugetlb-tolerate-uffd-bits-set-without-uffd-for-prot_none-ptes.patch
mm-hugetlb-tolerate-uffd_wp-markers-outside-uffd-wp-vmas.patch
mm-mremap-fix-calling-fixup_hugetlb_reservations-on-the-wrong-vma.patch
arm64-mm-move-__check_safe_pte_update-fix.patch
mm-sparse-move-mem_section-init-to-sparse_extreme_init.patch
mm-sparse-refactor-sparse_sections_init.patch
mm-sparse-move-initialization-of-section-metadata-to-sparse_metadata_init.patch
mm-sparse-rename-and-cleanup-sparse_init_nid.patch
mm-sparse-cleanup-sparse_init_one_section.patch
mm-sparse-rename-__highest_present_section_nr-to-__highest_used_section_nr.patch
mm-sparse-remove-pfn_in_present_section.patch
mm-sparse-move-__highest_used_section_nr-handling.patch
scripts-gdb-mmpy-remove-fallbacks-for-section_has_mem_map-and-section_is_early.patch
mm-sparse-remove-section_marked_present.patch
mm-sparse-remove-flags-parameter-from-sparse_init_one_section.patch
fs-proc-page-clarify-comment-in-get_max_dump_pfn.patch
mm-memory_hotplug-drop-config_have_arch_pfn_valid-handling-from-pfn_to_online_page.patch
vmcoreinfo-export-section_has_mem_map.patch
mm-disallow-ioremaping-ordinary-ram-in-generic_access_phys.patch
mm-userfaultfd-only-allocate-anon_vma-in-cow-mappings.patch