pfect_lru_node
sizeof(struct pfect_lru_node *),
lru->free_nodes = malloc(lru_size * sizeof(struct pfect_lru_node));
struct pfect_lru_node *node = NULL;
struct pfect_lru_node *null_node = NULL;
struct pfect_lru_node,
struct pfect_lru_node *free_nodes;