[merged mm-stable] userfaultfd-ensure-mremap_userfaultfd_fail-releases-mmap_changing.patch removed from -mm tree

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

The quilt patch titled
     Subject: userfaultfd: ensure mremap_userfaultfd_fail() releases mmap_changing
has been removed from the -mm tree.  Its filename was
     userfaultfd-ensure-mremap_userfaultfd_fail-releases-mmap_changing.patch

This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
Subject: userfaultfd: ensure mremap_userfaultfd_fail() releases mmap_changing
Date: Wed, 13 May 2026 11:14:16 +0300

Sashiko says:

  mremap_userfaultfd_prep() increments ctx->mmap_changing to stall
  concurrent operations, but mremap_userfaultfd_fail() does not
  decrement it before dropping the context reference.

If an mremap operation fails, ctx->mmap_changing remains elevated. This
will causes subsequent userfaultfd operations like a UFFDIO_COPY to fail
with -EAGAIN.

Decrement ctx->mmap_changing in mremap_userfaultfd_fail().

Link: https://sashiko.dev/#/patchset/20260430113512.115938-1-rppt@kernel.org
Link: https://lore.kernel.org/20260513081416.495963-1-rppt@kernel.org
Fixes: df2cc96e7701 ("userfaultfd: prevent non-cooperative events vs mcopy_atomic races")
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Peter Xu <peterx@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/userfaultfd.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/fs/userfaultfd.c~userfaultfd-ensure-mremap_userfaultfd_fail-releases-mmap_changing
+++ a/fs/userfaultfd.c
@@ -786,6 +786,8 @@ void mremap_userfaultfd_fail(struct vm_u
 	if (!ctx)
 		return;
 
+	atomic_dec(&ctx->mmap_changing);
+	VM_WARN_ON_ONCE(atomic_read(&ctx->mmap_changing) < 0);
 	userfaultfd_ctx_put(ctx);
 }
 
_

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

selftests-mm-hugetlb-read-hwpoison-add-sigbus-handler.patch
selftests-mm-migration-dont-assume-huge-page-is-twomeg.patch
selftests-mm-migration-make-nthreads-represent-number-of-working-threads.patch
selftests-mm-migration-properly-cleanup-forked-processes.patch
selftests-mm-run_vmtestssh-dont-gate-thp-and-ksm-tests-on-have_hugepages.patch
selftests-mm-merge-map_hugetlb-into-hugepage-mmap.patch
selftests-mm-rename-hugepage-tests-to-hugetlb.patch
selftests-mm-hugetlb-shm-use-kselftest-framework.patch
selftests-mm-hugetlb-vmemmap-use-kselftest-framework.patch
selftests-mm-hugetlb-madvise-use-kselftest-framework.patch
selftests-mm-hugetlb_madv_vs_map-use-kselftest-framework.patch
selftests-mm-hugetlb-read-hwpoison-use-kselftest-framework.patch
selftests-mm-khugepaged-group-tests-in-an-array.patch
selftests-mm-khugepaged-use-ksefltest-framework.patch
selftests-mm-khugepaged-use-ksefltest-framework-fix.patch
selftests-mm-ksm_tests-use-kselftest-framework.patch
selftests-mm-protection_keys-use-descriptive-test-names-in-the-output.patch
selftests-mm-protection_keys-use-kselftest-framework.patch
selftests-mm-uffd-common-use-kselftest-framework.patch
selftests-mm-uffd-stress-use-kselftest-framework.patch
selftests-mm-uffd-unit-tests-use-kselftest-framework.patch
selftests-mm-va_high_addr_switch-use-kselftest-framework.patch
selftests-mm-add-atexit-and-signal-handlers-to-thp_settings.patch
selftests-mm-rename-thp_settings-to-hugepage_settings.patch
selftests-mm-move-hugetlb-helpers-to-hugepage_settings.patch
selftests-mm-hugepage_settings-use-unsigned-long-in-detect_hugetlb_page_size.patch
selftests-mm-hugepage_settings-add-apis-to-get-and-set-nr_hugepages.patch
selftests-mm-hugepage_settings-rename-and-rework-get_free_hugepages.patch
selftests-mm-hugepage_settings-add-apis-for-hugetlb-setup-and-teardown.patch
selftests-mm-move-read_file-read_num-and-write_num-to-vm_util.patch
selftests-mm-vm_util-add-helpers-to-set-and-restore-shm-limits.patch
selftests-mm-compaction_test-use-hugetlb-helpers.patch
selftests-mm-cow-add-setup-of-hugetlb-pages.patch
selftests-mm-gup_longterm-add-setup-of-hugetlb-pages.patch
selftests-mm-gup_test-add-setup-of-hugetlb-pages.patch
selftests-mm-hmm-tests-add-setup-of-hugetlb-pages.patch
selftests-mm-hugepage_dio-add-setup-of-hugetlb-pages.patch
selftests-mm-hugetlb_fault_after_madv-add-setup-of-hugetlb-pages.patch
selftests-mm-hugetlb-madvise-add-setup-of-hugetlb-pages.patch
selftests-mm-hugetlb_madv_vs_map-add-setup-of-hugetlb-pages.patch
selftests-mm-hugetlb-mmap-add-setup-of-hugetlb-pages.patch
selftests-mm-hugetlb-mremap-add-setup-of-hugetlb-pages.patch
selftests-mm-hugetlb-shm-add-setup-of-hugetlb-pages.patch
selftests-mm-hugetlb-soft-offline-add-setup-of-hugetlb-pages.patch
selftests-mm-hugetlb-vmemmap-add-setup-of-hugetlb-pages.patch
selftests-mm-migration-add-setup-of-hugetlb-pages.patch
selftests-mm-pagemap_ioctl-add-setup-of-hugetlb-pages.patch
selftests-mm-protection_keys-use-library-code-for-hugetlb-setup.patch
selftests-mm-thuge-gen-add-setup-of-hugetlb-pages.patch
selftests-mm-uffd-stress-use-hugetlb_save-and-alloc-huge-pages.patch
selftests-mm-uffd-unit-tests-add-setup-of-hugetlb-pages.patch
selftests-mm-uffd-wp-mremap-add-setup-of-hugetlb-pages.patch
selftests-mm-va_high_addr_switch-add-setup-of-hugetlb-pages.patch
selftests-mm-va_high_addr_switchsh-drop-huge-pages-setup.patch
selftests-mm-run_vmtestssh-free-memory-if-available-memory-is-low.patch
selftests-mm-run_vmtestssh-drop-detection-and-setup-of-hugetlb.patch
xor-use-kmalloc-in-calibrate_xor_blocks.patch
raid6-use-kmalloc-in-raid6_select_algo.patch