mm/vmscan.c: fix typo

Change "optizimation" to "optimization".

Signed-off-by: dylan-meiners <spacct.spacct@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Link: http://lkml.kernel.org/r/20200609185144.10049-1-spacct.spacct@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/vmscan.c b/mm/vmscan.c
index d4d7cd1..dbabf812 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -910,7 +910,7 @@
 		 * order to detect refaults, thus thrashing, later on.
 		 *
 		 * But don't store shadows in an address space that is
-		 * already exiting.  This is not just an optizimation,
+		 * already exiting.  This is not just an optimization,
 		 * inode reclaim needs to empty out the radix tree or
 		 * the nodes are lost.  Don't plant shadows behind its
 		 * back.