[merged mm-hotfixes-stable] mm-migrate_device-fix-pte_pfn-pte_dirty-called-on-non-present-pte.patch removed from -mm tree

The quilt patch titled
     Subject: mm: migrate_device: fix pte_pfn/pte_dirty called on non-present PTE
has been removed from the -mm tree.  Its filename was
     mm-migrate_device-fix-pte_pfn-pte_dirty-called-on-non-present-pte.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: Kefeng Wang <[email protected]>
Subject: mm: migrate_device: fix pte_pfn/pte_dirty called on non-present PTE
Date: Mon, 6 Jul 2026 19:19:58 +0800

pte_pfn() and pte_dirty() have undefined behaviour when called on a
non-present PTE. In migrate_vma_collect_pmd(), these functions may be
invoked on non-present entries (e.g., device-private entries), leading
to potential crashes from pte_pfn() or incorrect dirty folio accounting
from pte_dirty(). Fix both by guarding with pte_present() checks.

Link: https://lore.kernel.org/[email protected]
Link: https://lore.kernel.org/[email protected]
Fixes: fd35ca3d12cc ("mm/migrate_device.c: copy pte dirty bit to page")
Fixes: 6c287605fd56 ("mm: remember exclusively mapped anonymous pages with PG_anon_exclusive")
Signed-off-by: Kefeng Wang <[email protected]>
Reviewed-by: Balbir Singh <[email protected]>
Acked-by: Zi Yan <[email protected]>
Cc: Alistair Popple <[email protected]>
Cc: Byungchul Park <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Gregory Price <[email protected]>
Cc: "Huang, Ying" <[email protected]>
Cc: Joshua Hahn <[email protected]>
Cc: Matthew Brost <[email protected]>
Cc: Rakie Kim <[email protected]>
Cc: Ying Huang <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---

 mm/migrate_device.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/mm/migrate_device.c~mm-migrate_device-fix-pte_pfn-pte_dirty-called-on-non-present-pte
+++ a/mm/migrate_device.c
@@ -401,7 +401,8 @@ again:
 			bool anon_exclusive;
 			pte_t swp_pte;
 
-			flush_cache_page(vma, addr, pte_pfn(pte));
+			if (pte_present(pte))
+				flush_cache_page(vma, addr, pte_pfn(pte));
 			anon_exclusive = folio_test_anon(folio) &&
 					  PageAnonExclusive(page);
 			if (anon_exclusive) {
@@ -422,7 +423,7 @@ again:
 			migrate->cpages++;
 
 			/* Set the dirty flag on the folio now the pte is gone. */
-			if (pte_dirty(pte))
+			if (pte_present(pte) && pte_dirty(pte))
 				folio_mark_dirty(folio);
 
 			/* Setup special migration page table entry */
_

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

mm-remove-pagetranscompound.patch
mm-mincore-use-walk_page_range_vma-in-do_mincore.patch
mm-mprotect-use-walk_page_range_vma-in-mprotect_fixup.patch
mm-mlock-use-walk_page_range_vma-in-mlock_vma_pages_range.patch
mm-migrate_device-use-walk_page_range_vma-in-migrate_vma_collect.patch
mm-introduce-pud_is_huge-helper.patch
mm-mincore-remove-special-handling-for-vm_pfnmap.patch
mm-mincore-remove-special-handling-for-vm_pfnmap-fix.patch
mm-mincore-replace-__get_free_page-with-kmalloc.patch
mm-mincore-remove-xa_is_value-in-mincore_swap.patch
mm-mincore-improve-mincore_hugetlb.patch
mm-mincore-improve-mincore_hugetlb-fix.patch
mm-mincore-refactor-mincore_page.patch