NR_NODE_STATES
BUILD_BUG_ON(ARRAY_SIZE(node_state_attr) != NR_NODE_STATES);
BUILD_BUG_ON(ARRAY_SIZE(node_state_attrs)-1 != NR_NODE_STATES);
extern nodemask_t node_states[NR_NODE_STATES];
if (state >= NR_NODE_STATES)
nodemask_t node_states[NR_NODE_STATES] __read_mostly = {