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mm-huge_memory-move-softleaf_to_folio-inside-migration-branch.patch removed from -mm tree

merged mm-stable Andrew Morton 1 participant 1 message Jul 31

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The quilt patch titled
Subject: mm/huge_memory: move softleaf_to_folio() inside migration branch
has been removed from the -mm tree. Its filename was
mm-huge_memory-move-softleaf_to_folio-inside-migration-branch.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/huge_memory: move softleaf_to_folio() inside migration branch
Date: Mon, 6 Jul 2026 04:42:06 -0700

change_non_present_huge_pmd() calls softleaf_to_folio() unconditionally at the top of the function. softleaf_to_folio() extracts a PFN from the entry and converts it to a folio pointer, which is only meaningful for migration and device_private entries that encode a real PFN.

A swap entry encodes a swap offset instead, so softleaf_to_folio() would produce a bogus pointer and crash on mprotect() when a PMD swap entry is present.

Move the call into the migration_write branch where the folio is actually used, so the function is safe for any non-present PMD type.

Link https://lore.kernel.org/[email protected] open here
Signed-off-by Usama Arif <[email protected]>
Acked-by David Hildenbrand (Arm) <[email protected]>
Reviewed-by Dev Jain <[email protected]>
Reviewed-by Zi Yan <[email protected]>
Cc Alexandre Ghiti <[email protected]>
Cc Baolin Wang <[email protected]>
Cc Baoquan He <[email protected]>
Cc Barry Song <[email protected]>
Cc Chris Li <[email protected]>
Cc "Huang, Ying" <[email protected]>
Cc Johannes Weiner <[email protected]>
Cc Kairui Song <[email protected]>
Cc Kemeng Shi <[email protected]>
Cc Kiryl Shutsemau <[email protected]>
Cc Lance Yang <[email protected]>
Cc Liam R. Howlett <[email protected]>
Cc Lorenzo Stoakes <[email protected]>
Cc Matthew Wilcox (Oracle) <[email protected]>
Cc Nhat Pham <[email protected]>
Cc Nico Pache <[email protected]>
Cc Rik van Riel <[email protected]>
Cc Ryan Roberts <[email protected]>
Cc Shakeel Butt <[email protected]>
Cc Vlastimil Babka <[email protected]>
Signed-off-by Andrew Morton <[email protected]>

---

 mm/huge_memory.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
mm/huge_memory.c renamed from mm/huge_memory.c~mm-huge_memory-move-softleaf_to_folio-inside-migration-branch +2 -1
@@ -2557,11 +2557,12 @@ static void change_non_present_huge_pmd(
 		bool uffd_wp_resolve)
 {
 	softleaf_t entry = softleaf_from_pmd(*pmd);
-	const struct folio *folio = softleaf_to_folio(entry);
 	pmd_t newpmd;
 
 	VM_WARN_ON(!pmd_is_valid_softleaf(*pmd));
 	if (softleaf_is_migration_write(entry)) {
+		const struct folio *folio = softleaf_to_folio(entry);
+
 		/*
 		 * A protection check is difficult so
 		 * just be safe and disable write

_

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

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