"This is mainly for kernel developers and desperate users."

I ran into the CONFIG_MODULES_FORCE_UNLOAD option today, and out of curiosity tried setting it and seeing what would happen.

livecd dev # rmmod -f cls_cgroup
Disabling lock debugging due to kernel taint
livecd dev # ls cgroup/
cgroup.procs net_cls.classid notify_on_release release_agent tasks
livecd dev # cat cgroup/net_cls.classid
cat: cgroup/net_cls.classid: Invalid argument
livecd dev # echo 1 > cgroup/net_cls.classid
bash: echo: write error: Invalid argument
livecd dev # umount cgroup

Modules linked in: [last unloaded: cls_cgroup]
Kernel panic - not syncing: Kernel mode fault at addr 0x0, ip 0x6017b8cc

I was impressed that it didn't die immediately when I tried looking at the file.

livecd / # modprobe cls_cgroup
livecd / # rmmod cls_cgroup
ERROR: Module cls_cgroup is in use
livecd / # rmmod -f cls_cgroup
Disabling lock debugging due to kernel taint
livecd / # cd /dev
livecd dev # mkdir cgroup
livecd dev # mount -t cgroup none -o cls_cgroup cgroup/

Modules linked in: [last unloaded: cls_cgroup]
Kernel panic - not syncing: Kernel mode fault at addr 0x0, ip 0x600fe9aa

Note that this is a case that I'd eventually like to get working with module unloading (without the -f option, of course).