Known bugs to be fixed
----------------------

* The non-owned processes sometimes show up with INT_MAX as their owner,
  instead of opt_anon_uid. This is likely to be a libps problem.

Improvements and new features
-----------------------------

* There is a lot of dynamic memory allocation going on and it comes with a
  cost in performance. We could try to limit such allocation, as long as it
  keeps the inner interface simple and preserves the read/readdir semantics
  (performance is probably not critical for a proc filesystem.)
  One way would be to add an (optional) "needed_length" field to
  procfs_node_ops, and arrange to pass a sufficient buffer in (*contents,
  *contents_len) when get_contents is called. Then the user-provided buffer
  might be used directly under some circumstances.

* Add thread directories as [pid]/task/[n]. This shouldn't be too hard if we
  use "process" nodes for threads, and provide an "exists" hook for the "task"
  entry itself so that it's disabled in thread nodes. It might prove necessary
  to have "optional" libps flags for some content generators, though, since
  some of them might be missing for threads.

