In 1.276 of kern/subr_trap.c I introduced a mechanism for delaying

a process return to userspace if it had pending GEOM events.

We need to have the same check in the exit pass to catch the case
where a GEOM related filedescriptor is not explicitly closed by
the process.

Bumped into by:	people using dd(1) to build releases, nanobsd etc.

sys/kern/kern_exit.c

@@ -237,6 +237,13 @@ exit1(struct thread *td, int rv)
 	fdfree(td);
 	mtx_unlock(&Giant);	
 
+	/*
+	 * If this thread tickled GEOM, we need to wait for the giggling to
+	 * stop before we return to userland
+	 */
+	if (td->td_pflags & TDP_GEOM)
+		g_waitidle();
+
 	/*
 	 * Remove ourself from our leader's peer list and wake our leader.
 	 */