[MemoryHandle.buffer()](https://github.com/viennacl/pyviennacl-dev/blob/master/pyviennacl/backend.py#L177) tries to use cl.MemoryObject.from_int_ptr which doesn't exist. Instead cl.Buffer.from_int_ptr should be used (see [here](https://github.com/pyopencl/pyopencl/issues/133)).