Cannot unload some modules

[(no name)]

    Hello all :))

    I have a problem with some modules, specially with 'dummy.o' (the
dummy network device driver) and some USB ones: they aren't unloaded,
even when unused and autocleanable, issuing two or more 'rmmod -a'
commands.

    This leaded me to think that the 'cleanup()' functions of those
modules did hang, but the modules are correctly unloaded if called by
their name in rmmod, but no if 'rmmod -a' is used :((

    I've took a look at 'module.c' and I'm clueless. I've checked the
modules and are loaded with 'modprobe -k', are marked as
autocleanable and marked as unused, too.

    BTW, I've noticed too that the serial module sometimes has a
negative value in its 'use' count :!!

    Can anybody tell me what could be happening?. Thanks a lot.

    Raśl