//shm/incr_map_anon.c
int
main(int argc, char **argv)
{
	int		i, nloop;
	int		*ptr;
	sem_t	*mutex;

	if (argc != 2)
		err_quit("usage: incr_map_anon <#loops>");
	nloop = atoi(argv[1]);

		/*    */
	ptr = Mmap(NULL, sizeof(int), PROT_READ | PROT_WRITE,
			   MAP_SHARED | MAP_ANON, -1, 0);
