--- x/mm/rmap.c
+++ y/mm/rmap.c
@@ -1466,6 +1466,7 @@ static __always_inline void __folio_add_
 void folio_add_file_rmap_ptes(struct folio *folio, struct page *page,
 		int nr_pages, struct vm_area_struct *vma)
 {
+	BUG_ON(!folio_test_locked(folio));
 	__folio_add_file_rmap(folio, page, nr_pages, vma, RMAP_LEVEL_PTE);
 }