It looks like some of these do make the file descriptor accessible to the Python user. The following are from the RST documentation:

oss_audio_device.fileno()
oss_mixer_device.fileno()
epoll.fileno()
kqueue.fileno()
audio device.fileno()

I did not find any documentation for the “linuxaudiodev” module, but it also seems to supply a public fileno() method:

$ sudo modprobe snd-pcm-oss
$ python2
Python 2.7.11 (default, Dec  6 2015, 15:43:46) 
[GCC 5.2.0] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import linuxaudiodev
>>> a = linuxaudiodev.open("w")
>>> a.fileno()
3

Unless there is demand for making these cases non-inheritable, it might be safest to leave them be. However it looks like the mmap file descriptor could be internal (though I’m not an expert on that module to be sure). So you might be okay with the mmap change.