diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index ee633712bba0..59f1df0cde5a 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -381,6 +381,10 @@ static inline void mapping_set_large_folios(struct address_space *mapping)
  */
 static inline bool mapping_large_folio_support(struct address_space *mapping)
 {
+	/* AS_LARGE_FOLIO_SUPPORT is only reasonable for pagecache folios */
+	VM_WARN_ONCE((unsigned long)mapping & PAGE_MAPPING_ANON,
+			"Anonymous mapping always supports large folio");
+
 	return IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
 		test_bit(AS_LARGE_FOLIO_SUPPORT, &mapping->flags);
 }
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 89932fd0f62e..db7946a0a28c 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3009,30 +3009,36 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
 	if (new_order >= folio_order(folio))
 		return -EINVAL;
 
-	/* Cannot split anonymous THP to order-1 */
-	if (new_order == 1 && folio_test_anon(folio)) {
-		VM_WARN_ONCE(1, "Cannot split to order-1 folio");
-		return -EINVAL;
-	}
-
-	if (new_order) {
-		/* Only swapping a whole PMD-mapped folio is supported */
-		if (folio_test_swapcache(folio))
+	if (folio_test_anon(folio)) {
+		/* order-1 is not supported for anonymous THP. */
+		if (new_order == 1) {
+			VM_WARN_ONCE(1, "Cannot split to order-1 folio");
 			return -EINVAL;
+		}
+	} else if (new_order) {
 		/* Split shmem folio to non-zero order not supported */
 		if (shmem_mapping(folio->mapping)) {
 			VM_WARN_ONCE(1,
 				"Cannot split shmem folio to non-0 order");
 			return -EINVAL;
 		}
-		/* No split if the file system does not support large folio */
-		if (!mapping_large_folio_support(folio->mapping)) {
+		/*
+		 * No split if the file system does not support large folio.
+		 * Note that we might still have THPs in such mappings due to
+		 * CONFIG_READ_ONLY_THP_FOR_FS. But in that case, the mapping
+		 * does not actually support large folios properly.
+		 */
+		if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) &&
+		    !mapping_large_folio_support(folio->mapping)) {
 			VM_WARN_ONCE(1,
 				"Cannot split file folio to non-0 order");
 			return -EINVAL;
 		}
 	}
 
+	/* Only swapping a whole PMD-mapped folio is supported */
+	if (folio_test_swapcache(folio) && new_order)
+		return -EINVAL;
 
 	is_hzp = is_huge_zero_folio(folio);
 	if (is_hzp) {