OSError 38 [Errno 38] with multiprocessing

У меня следующая ошибка:

$ sudo chmod a+rwxt /dev/shm/
$ ls -ld /dev/shm/
drwxrwxrwt 2 root root 4096 Feb  4 06:56 /dev/shm/
$ python
Python 2.6.6 (r266:84292, Dec 26 2010, 22:31:48) 
[GCC 4.4.5] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import multiprocessing
>>> mp = multiprocessing.Pool(2)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.6/multiprocessing/__init__.py", line 227, in Pool
    return Pool(processes, initializer, initargs)
  File "/usr/lib/python2.6/multiprocessing/pool.py", line 84, in __init__
    self._setup_queues()
  File "/usr/lib/python2.6/multiprocessing/pool.py", line 131, in _setup_queues
    self._inqueue = SimpleQueue()
  File "/usr/lib/python2.6/multiprocessing/queues.py", line 328, in __init__
    self._rlock = Lock()
  File "/usr/lib/python2.6/multiprocessing/synchronize.py", line 117, in __init__
    SemLock.__init__(self, SEMAPHORE, 1, 1)
  File "/usr/lib/python2.6/multiprocessing/synchronize.py", line 49, in __init__
    sl = self._semlock = _multiprocessing.SemLock(kind, value, maxvalue)
OSError: [Errno 38] Function not implemented

Что еще может быть причиной этой ошибки ( кроме доступа для чтения / записи в / dev / shm)?

Спасибо!