[issue174] Unloading md module causes a panic

[Nicolas Thery]

2009/2/1 Nicolas Thery <nthery at gmail.com>:
> 2009/1/22 Antonio Huete Jimenez (via DragonFly issue tracker)
> <sinknull at crater.dragonflybsd.org>:
>>
>> Antonio Huete Jimenez <tuxillo at quantumachine.net> added the comment:
>>
>> Still happening on 2.0.1
>> See attached image.
>
> I can reproduce it if and only if md is already compiled in the kernel.
>
> What happens is that when kldloading md, the kernel tries to register
> the debug.mddebug sysctl a second time (as md is already in the
> kernel).  It complains (the "can't re-use a leaf" msg) and stops the
> registration but carries on loading the module.
>
> When kldunloading, the kernel tries to unregister the module instance
> of debug.mddebug and panics because it was not registered in the first
> place.
>
> Is there a way to detect during kldload that the module is already
> part of the kernel?
>
> I propose to close this bug as it is caused by incorrect user manipulation.

Well, actually as Simon mentioned earlier, md has not been updated to
work as a module and it leaks memory when unloaded.  I'm looking into
it.