psutil.virtual_memory() crashes on FreeBSD

[syohex]

psutil.virtual_memory() raises exception from psutil 3.4.1. There is no exception with 3.3.0.

3.4.1

% python2.7
Python 2.7.11 (default, Jan 19 2016, 15:10:11)
[GCC 4.2.1 Compatible FreeBSD Clang 3.4.1 (tags/RELEASE_34/dot1-final 208032)] on freebsd10
Type "help", "copyright", "credits" or "license" for more information.
>>> import psutil
>>> psutil.__version__
'3.4.1'
>>> psutil.virtual_memory()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python2.7/site-packages/psutil/__init__.py", line 1676, in virtual_memory
    ret = _psplatform.virtual_memory()
  File "/usr/local/lib/python2.7/site-packages/psutil/_psbsd.py", line 119, in virtual_memory
    mem = cext.virtual_mem()
OSError: [Errno 12] Cannot allocate memory

3.3.0

% python2.7
Python 2.7.11 (default, Jan 19 2016, 15:10:11)
[GCC 4.2.1 Compatible FreeBSD Clang 3.4.1 (tags/RELEASE_34/dot1-final 208032)] on freebsd10
Type "help", "copyright", "credits" or "license" for more information.
>>> import psutil
>>> psutil.__version__
'3.3.0'

>>> psutil.virtual_memory()
svmem(total=1020645376L, available=819802112L, percent=19.7, used=212234240L, free=52613120L, active=35495936L, inactive=755793920L, buffers=110297088L, cached=11395072L, shared=39469056L, wired=165343232L)

My environment

• FreeBSD 10.2-RELEASE r286666 amd64
• Python 2.7.11

This is related to nicolargo/glances#781