Well, radeon_uvd_free_handles is only called if an application crashed or
didn't cleaned up the VDPAU driver correctly. (e.g. the kernel needs to
manually tell the hardware that a decoder isn't needed any more because the
application failed to do so).

So it's definately some kind of userspace problem involved here.

But neverless there is also something wrong with the kernel function, otherwise
you won't get -22 (-EINVAL) in your dmesg.