mm: Rename folio_test_multi to folio_test_large

This is a better name.  Also add kernel-doc.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

include/linux/page-flags.h

@@ -692,7 +692,13 @@ static inline bool folio_test_single(struct folio *folio)
 	return !folio_test_head(folio);
 }
 
-static inline bool folio_test_multi(struct folio *folio)
+/**
+ * folio_test_large() - Does this folio contain more than one page?
+ * @folio: The folio to test.
+ *
+ * Return: True if the folio is larger than one page.
+ */
+static inline bool folio_test_large(struct folio *folio)
 {
 	return folio_test_head(folio);
 }

mm/memcontrol.c

@@ -5558,7 +5558,7 @@ static int mem_cgroup_move_account(struct page *page,
 
 	VM_BUG_ON(from == to);
 	VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
-	VM_BUG_ON(compound && !folio_test_multi(folio));
+	VM_BUG_ON(compound && !folio_test_large(folio));
 
 	/*
 	 * Prevent mem_cgroup_migrate() from looking at