mempolicy: remove redundant code

1.  In funtion is_valid_nodemask(), varibable k will be inited to 0 in
   the following loop, needn't init to policy_zone anymore.

2. (MPOL_F_STATIC_NODES | MPOL_F_RELATIVE_NODES) has already defined
   to MPOL_MODE_FLAGS in mempolicy.h.

Signed-off-by: Bob Liu <lliubbo@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/mempolicy.c

@@ -127,9 +127,6 @@ static int is_valid_nodemask(const nodemask_t *nodemask)
 {
 	int nd, k;
 
-	/* Check that there is something useful in this mask */
-	k = policy_zone;
-
 	for_each_node_mask(nd, *nodemask) {
 		struct zone *z;
 
@@ -145,7 +142,7 @@ static int is_valid_nodemask(const nodemask_t *nodemask)
 
 static inline int mpol_store_user_nodemask(const struct mempolicy *pol)
 {
-	return pol->flags & (MPOL_F_STATIC_NODES | MPOL_F_RELATIVE_NODES);
+	return pol->flags & MPOL_MODE_FLAGS;
 }
 
 static void mpol_relative_nodemask(nodemask_t *ret, const nodemask_t *orig,