[RFE] Who's using a module?

[Konstantin Kharlamov <hi-angel@yandex.ru>]

Once in a while there's a need to remove a module (for example because you rebuilt it, or to reload it with different parameters, or whatever…). And then doing `rmmod modulename` and `modprobe -r modulename` gives:

	rmmod: ERROR: Module modulename is in use

If you're lucky, firing up `lsmod | grep modulename` will get you offenders inside "used by" column. But often there's nothing except the count above zero. It is very easy to reproduce if you check `lsmod` output for your graphics driver. I checked it on `i915` and `amdgpu`: when graphics session is opened you can't remove it and `lsmod` doesn't show who's using it.

There's very popular and old question on SO¹ that at the moment has over 55k views, and the only answer that seem to work for people is insanely big and convoluted; it is using a custom kernel driver and kernel tracing capabilities. I guess this amount of research means: no, currently there's no easy way to get who's using a module.

It would be amazing if kernel has capability to figure out who's using a module.

1: https://stackoverflow.com/questions/448999/is-there-a-way-to-figure-out-what-is-using-a-linux-kernel-module

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