page_isolation: Fix a comment typo in test_pages_isolated()

pageblock_nr_page should be pageblock_nr_pages, and fist is
a typo of first.

Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index 383bdbb9..0cee10f 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -226,9 +226,9 @@
 	int ret;
 
 	/*
-	 * Note: pageblock_nr_page != MAX_ORDER. Then, chunks of free page
-	 * is not aligned to pageblock_nr_pages.
-	 * Then we just check pagetype fist.
+	 * Note: pageblock_nr_pages != MAX_ORDER. Then, chunks of free pages
+	 * are not aligned to pageblock_nr_pages.
+	 * Then we just check migratetype first.
 	 */
 	for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
 		page = __first_valid_page(pfn, pageblock_nr_pages);
@@ -238,7 +238,7 @@
 	page = __first_valid_page(start_pfn, end_pfn - start_pfn);
 	if ((pfn < end_pfn) || !page)
 		return -EBUSY;
-	/* Check all pages are free or Marked as ISOLATED */
+	/* Check all pages are free or marked as ISOLATED */
 	zone = page_zone(page);
 	spin_lock_irqsave(&zone->lock, flags);
 	ret = __test_page_isolated_in_pageblock(start_pfn, end_pfn,