Found it at http://www.linuxquestions.org/questions/suse-novell-60/howto-kill-defunct-processes-574612/
2) Here a great tip from another user (Thxs Bill Dandreta): Sometimes
kill -9 <pid>
will not kill a process. Run
ps -xal
the 4th field is the parent process, kill all of a zombie's parents and the zombie dies!
Example
4 0 18581 31706 17 0 2664 1236 wait S ? 0:00 sh -c /usr/bin/gcc -fomit-frame-pointer -O -mfpmat
4 0 18582 18581 17 0 2064 828 wait S ? 0:00 /usr/i686-pc-linux-gnu/gcc-bin/3.3.6/gcc -fomit-fr
4 0 18583 18582 21 0 6684 3100 - R ? 0:00 /usr/lib/gcc-lib/i686-pc-linux-gnu/3.3.6/cc1 -quie
18581
, 18582
, 18583
are zombies -
kill -9 18581 18582 18583
has no effect.
kill -9 31706
removes the zombies.