mm/hugetlb.c: fix error-path memory leak in nr_hugepages_store_common()

The NODEMASK_ALLOC macro may dynamically allocate memory for its second
argument ('nodes_allowed' in this context).

In nr_hugepages_store_common() we may abort early if strict_strtoul()
fails, but in that case we do not free the memory already allocated to
'nodes_allowed', causing a memory leak.

This patch closes the leak by freeing the memory in the error path.

[akpm@linux-foundation.org: use NODEMASK_FREE, per Minchan Kim]
Signed-off-by: NJesper Juhl <jj@chaosbits.net>
Cc: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/hugetlb.c

@@ -1374,8 +1374,10 @@ static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
 	NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
 
 	err = strict_strtoul(buf, 10, &count);
-	if (err)
+	if (err) {
+		NODEMASK_FREE(nodes_allowed);
 		return 0;
+	}
 
 	h = kobj_to_hstate(kobj, &nid);
 	if (nid == NUMA_NO_NODE) {