mm/swap.c: __pagevec_lru_add_fn: typo fix

There is no function named munlock_vma_pages().  Correct it to
munlock_vma_page().

Link: http://lkml.kernel.org/r/20190402095609.27181-1-peng.fan@nxp.com
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Mukesh Ojha <mojha@codeaurora.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/swap.c

@@ -867,7 +867,7 @@ static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec,
 	SetPageLRU(page);
 	/*
 	 * Page becomes evictable in two ways:
-	 * 1) Within LRU lock [munlock_vma_pages() and __munlock_pagevec()].
+	 * 1) Within LRU lock [munlock_vma_page() and __munlock_pagevec()].
 	 * 2) Before acquiring LRU lock to put the page to correct LRU and then
 	 *   a) do PageLRU check with lock [check_move_unevictable_pages]
 	 *   b) do PageLRU check before lock [clear_page_mlock]