in function find_entry_freq, freqman.c does
Ibalancer *balancer = mm->GetInterface(I_BALANCER, arena);
and then never releases it. This leads to errors when the modules are unloading since freqman can not unregister the interface because the reference count is nonzero.
EDIT: included a patch file to fix it. Run "patch freqman.c < freqman.patch"