Comment 15 for bug 1502946

Here is a bit more of that code for context:

static int __init numa_register_memblks(struct numa_meminfo *mi)
{
 unsigned long uninitialized_var(pfn_align);
 int i, nid;

 /* Account for nodes with cpus and no memory */
 node_possible_map = numa_nodes_parsed;
 numa_nodemask_from_meminfo(&node_possible_map, mi);
 if (WARN_ON(nodes_empty(node_possible_map)))
  return -EINVAL;