System error when I start a container by "--net=host"

Deal All:

I start a container by follow command:
docker run -v /root/install:/mnt --net=host --name=softtest -it --privileged=true 50df194e281b /bin/bash

but I get errors when I create a new user by follow command in above container:
useradd -d /home/softtest -m softtest
only error info:System error

if I use “–net=bridge” to create container, there is no error.

HOST OS:
Ubuntu 12.04.5 LTS

IMAGE OS:
SUSE Linux Enterprise Server 11 SP3 (x86_64)

Docker:
Client:
Version: 1.11.1
API version: 1.23
Go version: go1.5.4
Git commit: 5604cbe
Built: Tue Apr 26 23:24:27 2016
OS/Arch: linux/amd64

Server:
Version: 1.11.1
API version: 1.23
Go version: go1.5.4
Git commit: 5604cbe
Built: Tue Apr 26 23:24:27 2016
OS/Arch: linux/amd64

Thanks

The Ubuntu version may not be supported. Is the version one of the following?
Ubuntu Xenial 16.04 (LTS)
Ubuntu Wily 15.10
Ubuntu Trusty 14.04 (LTS)
Ubuntu Precise 12.04 (LTS)
https://docs.docker.com/engine/installation/linux/ubuntulinux/

version is supported.

Ubuntu version:
Distributor ID: Ubuntu
Description: Ubuntu 12.04.5 LTS
Release: 12.04
Codename: precise
root@jya-SBCR:/# cat /etc/issue
Ubuntu 12.04.5 LTS \n \l

Kenerl vserion:
3.13.0-86-generic