contigmalloc() and mmap()

[Christoph Hellwig]

On Mon, Jun 13, 2005 at 12:37:07PM -0600, Scott Long wrote:
> How does linux handle the implications of fork(2) in this scenario?

it's still counted as the same instance.  Similar for dup or passing
descriptors over AF_UNIX sockets. The data is explictly not per-process
but per instance.

There's not a lot of users actually using this feature, only the tty
subsystem and multi-channel sound drivers for the old oss API that
allowed multiple opens of /dev/dsp that way come to mind.

Lot's of driver use file->private to get at per-device data easily,
but that's just a shortcut.