title: CUDARuntimeError with Chainer
body: <pre><code>chainer.cuda.available
  </code></pre>
  
  <p>and</p>
  
  <pre><code>chainer.cuda.cudnn_enabled
  </code></pre>
  
  <p>both return 'True'.</p>
  
  <p>But when I try</p>
  
  <pre><code>    cuda.to_gpu(data, 1)
  </code></pre>
  
  <p>it gives the following error -</p>
  
  <pre><code>CUDARuntimeError                          Traceback (most recent call last)
  &lt;ipython-input-3-87cf96844cac&gt; in &lt;module&gt;()
  ----&gt; 1 cuda.to_gpu(data, 1)
  
  /home/shreez/anaconda3/lib/python3.5/site-packages/chainer/cuda.py in to_gpu(array, device, stream)
  192     check_cuda_available()
  193     assert stream is None  # TODO(beam2d): FIX IT
  --&gt; 194     with get_device(device):
  195         dev_id = int(get_device(array))
  196         if dev_id != -1 and dev_id != cupy.cuda.device.get_device_id():
  
  cupy/cuda/device.pyx in cupy.cuda.device.Device.__enter__ (cupy/cuda/device.cpp:1503)()
  
  cupy/cuda/device.pyx in cupy.cuda.device.Device.use (cupy/cuda/device.cpp:1753)()
  
  cupy/cuda/runtime.pyx in cupy.cuda.runtime.setDevice (cupy/cuda/runtime.cpp:2428)()
  
  cupy/cuda/runtime.pyx in cupy.cuda.runtime.check_status (cupy/cuda/runtime.cpp:1821)()
  
  CUDARuntimeError: cudaErrorInvalidDevice: invalid device ordinal
  </code></pre>
  
  <p>System information:</p>
  
  <p>I am using nvidia driver version 364.19 with Ubuntu 14.04. Chainer is installed with Anaconda 3, chainer version = 1.8.2</p>
  
  <p>nvcc --version returns the following:</p>
  
  <pre><code>nvcc: NVIDIA (R) Cuda compiler driver
  Copyright (c) 2005-2015 NVIDIA Corporation
  Built on Tue_Aug_11_14:27:32_CDT_2015
  Cuda compilation tools, release 7.5, V7.5.17
  </code></pre>