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: NTang Chen <tangchen@cn.fujitsu.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

mm/page_isolation.c

@@ -226,9 +226,9 @@ int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn,
 	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 @@ int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn,
 	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,