mm-madvise-skip-device-private-pmds-in-cold-and-pageout-walks.patch removed from -mm tree

The quilt patch titled
Subject: mm/madvise: skip device-private PMDs in cold and pageout walks
has been removed from the -mm tree. Its filename was
mm-madvise-skip-device-private-pmds-in-cold-and-pageout-walks.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: Usama Arif <[email protected]>
Subject: mm/madvise: skip device-private PMDs in cold and pageout walks
Date: Fri, 10 Jul 2026 03:55:22 -0700

madvise_cold_or_pageout_pte_range() takes pmd_trans_huge_lock(), whose pmd_is_huge() check returns true for a device-private PMD. The subsequent !pmd_present() branch has a VM_BUG_ON() asserting migration is the only allowed non-present case; a device-private PMD trips it.

Skip device-private PMDs in that non-present branch and continue to huge_unlock before calling pmd_folio(). Downgrade the check to VM_WARN_ON_ONCE() so an unexpected PMD softleaf logs a warning rather than panicking. Drop the thp_migration_supported() guard: it expands to IS_ENABLED(CONFIG_ARCH_SUPPORTS_PMD_SOFTLEAF), and both pmd_is_migration_entry() and pmd_is_device_private_entry() already return false when that config is not selected, so the guard suppresses only the case where the warning would already be silent.

Potential trigger: an HMM-based GPU driver races with madvise(MADV_COLD)/MADV_PAGEOUT: pmd_trans_huge(*pmd) reads true, then migrate_vma_pages() flips the PMD to a device-private entry before the PMD lock is acquired.

---

 mm/madvise.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

@@ -388,8 +388,8 @@ static int madvise_cold_or_pageout_pte_r
 			goto huge_unlock;
 
 		if (unlikely(!pmd_present(orig_pmd))) {
-			VM_BUG_ON(thp_migration_supported() &&
-					!pmd_is_migration_entry(orig_pmd));
+			VM_WARN_ON_ONCE(!pmd_is_migration_entry(orig_pmd) &&
+					!pmd_is_device_private_entry(orig_pmd));
 			goto huge_unlock;
 		}
 

_

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

mm-vmstat-mm-memcontrol-add-_monotonic-vmstat-readers.patch mm-vmscan-add-pgrotate_anon-and-pgrotate_file-vmstat-counters.patch mm-vmscan-reduce-lru_lock-contention-via-vmstat-derived-scan-balance-cost.patch