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userfaultfd-wait-on-source-pmd-during-uffdio_move.patch removed from -mm tree

merged mm-hotfixes-stable Andrew Morton 1 participant 1 message Jul 21 Stable branch

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The quilt patch titled
Subject: userfaultfd: wait on source PMD during UFFDIO_MOVE
has been removed from the -mm tree. Its filename was
userfaultfd-wait-on-source-pmd-during-uffdio_move.patch

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

------------------------------------------------------
From: Usama Arif <[email protected]>
Subject: userfaultfd: wait on source PMD during UFFDIO_MOVE
Date: Sun, 5 Jul 2026 06:12:31 -0700

move_pages_huge_pmd() snapshots src_pmdval under src_ptl, drops the lock, and, for migration entries, waits with pmd_migration_entry_wait().

Passing &src_pmdval is wrong. pmd_migration_entry_wait() must lock and re-read the real page-table PMD; on split-PMD-lock kernels, a stack address also resolves to the wrong lock. softleaf_entry_wait_on_locked() then waits without a folio reference, which is safe only while serialized against migration-entry removal by the real PT lock.

Pass src_pmd, matching __handle_mm_fault() and hmm_vma_walk_pmd().

Link https://lore.kernel.org/[email protected] open here
Fixes adef440691ba ("userfaultfd: UFFDIO_MOVE uABI")
Reported-by sashiko-bot <[email protected]>
Link https://sashiko.dev/#/patchset/20260703173903.3789516-1-usama.arif%40linux.dev?part=8
Signed-off-by Usama Arif <[email protected]>
Reviewed-by Rik van Riel <[email protected]>
Reviewed-by Baolin Wang <[email protected]>
Reviewed-by Lance Yang <[email protected]>
Acked-by David Hildenbrand (Arm) <[email protected]>
Reviewed-by Lance Yang <[email protected]>
Reviewed-by Lorenzo Stoakes <[email protected]>
Cc Andrea Arcangeli <[email protected]>
Cc Barry Song <[email protected]>
Cc Dev Jain <[email protected]>
Cc Johannes Weiner <[email protected]>
Cc Liam R. Howlett <[email protected]>
Cc Nico Pache <[email protected]>
Cc Ryan Roberts <[email protected]>
Cc Shakeel Butt <[email protected]>
Cc Zi Yan <[email protected]>
Cc <[email protected]>
Signed-off-by Andrew Morton <[email protected]>

---

 mm/huge_memory.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
mm/huge_memory.c renamed from mm/huge_memory.c~userfaultfd-wait-on-source-pmd-during-uffdio_move +1 -1
@@ -2774,7 +2774,7 @@ int move_pages_huge_pmd(struct mm_struct
 	if (!pmd_trans_huge(src_pmdval)) {
 		spin_unlock(src_ptl);
 		if (pmd_is_migration_entry(src_pmdval)) {
-			pmd_migration_entry_wait(mm, &src_pmdval);
+			pmd_migration_entry_wait(mm, src_pmd);
 			return -EAGAIN;
 		}
 		return -ENOENT;

_

Patches currently in -mm which might be from [email protected] are

mm-swap_state-remove-unnecessary-lru_add_drain-from-readahead.patch mm-add-softleaf_to_pmd-and-convert-existing-callers.patch mm-extract-mm_prepare_for_swap_entries-helper.patch fs-proc-use-softleaf_has_pfn-in-pagemap-pmd-walker.patch mm-huge_memory-move-softleaf_to_folio-inside-migration-branch.patch mm-migrate_device-move-softleaf_to_folio-inside-device-private-branch.patch mm-rename-arch_enable_thp_migration-to-arch_has_pmd_softleaves.patch mm-vmpressure-skip-tree=true-accounting-on-cgroup-v2.patch mm-vmpressure-skip-tree=true-accounting-on-cgroup-v2-fix.patch mm-vmpressure-move-v1-userspace-eventfd-code-into-memcontrol-v1c.patch mm-migrate_device-pin-large-folios-before-splitting.patch mm-migrate_device-pin-large-folios-before-splitting-fix.patch mm-mempolicy-skip-non-present-pmds-when-queueing-folios.patch mm-madvise-skip-device-private-pmds-in-cold-and-pageout-walks.patch mm-huge_memory-skip-device-private-pmds-in-madvise_free_huge_pmd.patch