mm/mempolicy: return NULL if node is NUMA_NO_NODE in get_task_policy

If node == NUMA_NO_NODE, pol is NULL, we should return NULL instead of
do "if (!pol->mode)" check.

[akpm@linux-foundation.org: reorganise code]
Signed-off-by: Jianguo Wu <wujianguo@huawei.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/mempolicy.c

@@ -123,16 +123,19 @@ static struct mempolicy preferred_node_policy[MAX_NUMNODES];
 static struct mempolicy *get_task_policy(struct task_struct *p)
 {
 	struct mempolicy *pol = p->mempolicy;
-	int node;
 
 	if (!pol) {
-		node = numa_node_id();
-		if (node != NUMA_NO_NODE)
-			pol = &preferred_node_policy[node];
+		int node = numa_node_id();
 
-		/* preferred_node_policy is not initialised early in boot */
-		if (!pol->mode)
-			pol = NULL;
+		if (node != NUMA_NO_NODE) {
+			pol = &preferred_node_policy[node];
+			/*
+			 * preferred_node_policy is not initialised early in
+			 * boot
+			 */
+			if (!pol->mode)
+				pol = NULL;
+		}
 	}
 
 	return pol;