[PATCH] Fix sysrq-t free stack output

It seems that we're attempting to work out the free stack size using two
unrelated pointers for the lowest address of the stack.  Fix this to use
the correct pointer.

kernel/sched.c

@@ -2465,7 +2465,7 @@ static void show_task(task_t * p)
 		unsigned long * n = (unsigned long *) (p->thread_info+1);
 		while (!*n)
 			n++;
-		free = (unsigned long) n - (unsigned long)(p+1);
+		free = (unsigned long) n - (unsigned long)(p->thread_info+1);
 	}
 	printk("%5lu %5d %6d ", free, p->pid, p->parent->pid);
 	if ((relative = eldest_child(p)))