Peek __mach_task_self_ value before proc_dostop call to work around kernel paging bug.

sysdeps/mach/hurd/fork.c

@@ -121,6 +121,8 @@ __fork (void)
 	__spin_lock (&_hurd_ports[i].lock);
       ports_locked = 1;
 
+      *(volatile task_t *) &__mach_task_self_; /* XXX work around kernel bug */
+
       /* Stop all other threads while copying the address space,
 	 so nothing changes.  */
       err = __proc_dostop (_hurd_ports[INIT_PORT_PROC].port, ss->thread);