can't execute nvidia runtime on docker

i'm trying to get nvidia-docker to run on my centos7 system:

$ cat /etc/systemd/system/docker.service.d/override.conf
[Service]
ExecStart=
ExecStart=/usr/bin/dockerd-current --add-runtime docker-runc=/usr/libexec/docker/docker-runc-current --add-runtime=nvidia=/usr/bin/nvidia-container-runtime --default-runtime=docker-runc --exec-opt native.cgroupdriver=systemd --userland-proxy-path=/usr/libexec/docker/docker-proxy-current --seccomp-profile=/etc/docker/seccomp.json $OPTIONS $DOCKER_STORAGE_OPTIONS $DOCKER_NETWORK_OPTIONS $ADD_REGISTRY $BLOCK_REGISTRY $INSECURE_REGISTRY $REGISTRIES

$ cat /etc/docker/daemon.json
{
}

$ docker --version
Docker version 1.13.1, build 774336d/1.13.1

$ sudo systemctl daemon-reload
$ sudo systemctl restart docker

so far so good:

    $ sudo docker run hello-world

Hello from Docker!
This message shows that your installation appears to be working correctly.

To generate this message, Docker took the following steps:
 1. The Docker client contacted the Docker daemon.
 2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
    (amd64)
 3. The Docker daemon created a new container from that image which runs the
    executable that produces the output you are currently reading.
 4. The Docker daemon streamed that output to the Docker client, which sent it
    to your terminal.

To try something more ambitious, you can run an Ubuntu container with:
 $ docker run -it ubuntu bash

Share images, automate workflows, and more with a free Docker ID:
 https://hub.docker.com/

For more examples and ideas, visit:
 https://docs.docker.com/engine/userguide/

now, lets try with the nvidia runtime:

$ sudo docker run --runtime=nvidia --rm nvidia/cuda nvidia-smi
standard_init_linux.go:178: exec user process caused "permission denied"

but strangely...

$ sudo docker run --runtime=nvidia --rm nvidia/cuda sh -c nvidia-smi
Wed May 16 06:41:17 2018
+-----------------------------------------------------------------------------+
| NVIDIA-SMI 390.42                 Driver Version: 390.42                    |
|-------------------------------+----------------------+----------------------+
| GPU  Name        Persistence-M| Bus-Id        Disp.A | Volatile Uncorr. ECC |
| Fan  Temp  Perf  Pwr:Usage/Cap|         Memory-Usage | GPU-Util  Compute M. |
|===============================+======================+======================|
|   0  Tesla K80           Off  | 00000000:06:00.0 Off |                    0 |
| N/A   28C    P8    26W / 149W |      0MiB / 11441MiB |      0%      Default |
+-------------------------------+----------------------+----------------------+

so... in the end i completely disabled selinux and rebooted and that fixed it.