mm: fix some typos in mm directory

No functional change.

Link: http://lkml.kernel.org/r/20190118235123.27843-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 9be9a22..ec25045 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -7551,7 +7551,7 @@ static void __setup_per_zone_wmarks(void)
 			 * value here.
 			 *
 			 * The WMARK_HIGH-WMARK_LOW and (WMARK_LOW-WMARK_MIN)
-			 * deltas control asynch page reclaim, and so should
+			 * deltas control async page reclaim, and so should
 			 * not be capped for highmem.
 			 */
 			unsigned long min_pages;
@@ -8028,7 +8028,7 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
 
 		/*
 		 * Hugepages are not in LRU lists, but they're movable.
-		 * We need not scan over tail pages bacause we don't
+		 * We need not scan over tail pages because we don't
 		 * handle each tail page individually in migration.
 		 */
 		if (PageHuge(page)) {