I've done backup in sys/netproto/smb to the version before
'cvs commit: src/sys/netproto/smb smb_iod.c smb_subr.c smb_subr.h' at Thu, 6 Jan 2005 14:31:16 -0800 (PST),
rebuild smbfs and the problem is gone: no zombies and no system crash after `kldunload smbfs; ps`.
It seems that the problem in this commit.
--
Sergey Gluschenko