问题描述：
有一台使用中的docker突然发生了故障，然后重启失败。最后将这台机器的docker卸载后重装，但是docker还是起不来，启动docker报“Error starting daemon: SELinux is not supported with the overlay2 graph driver on this kernel.”的错误。具体的报错信息如下：
[root@registry lib]# systemctl start docker
Job for docker.service failed because the control process exited with error code. See "systemctl status docker.service" and "journalctl -xe" for details.
[root@registry lib]# systemctl status docker.service
● docker.service - Docker Application Container Engine
Loaded: loaded (/usr/lib/systemd/system/docker.service; disabled; vendor preset: disabled)
Active: failed (Result: exit-code) since Fri 2018-06-22 15:22:45 CST; 10s ago
Docs: http://docs.docker.com
Process: 6374 ExecStart=/usr/bin/dockerd-current --add-runtime docker-runc=/usr/libexec/docker/docker-runc-current --default-runtime=docker-runc --exec-opt native.cgroupdriver=systemd --userland-proxy-path=/usr/libexec/docker/docker-proxy-current --init-path=/usr/libexec/docker/docker-init-current --seccomp-profile=/etc/docker/seccomp.json $OPTIONS $DOCKER_STORAGE_OPTIONS $DOCKER_NETWORK_OPTIONS $ADD_REGISTRY $BLOCK_REGISTRY $INSECURE_REGISTRY $REGISTRIES (code=exited, status=1/FAILURE)
Main PID: 6374 (code=exited, status=1/FAILURE)
Jun 22 15:22:42 registry.sefon.com systemd[1]: Starting Docker Application Container Engine...
Jun 22 15:22:42 registry.sefon.com dockerd-current[6374]: time="2018-06-22T15:22:42.987932115+08:00" level=info msg="libcontainerd: new containerd process, pid: 6381"
Jun 22 15:22:45 registry.sefon.com dockerd-current[6374]: Error starting daemon: SELinux is not supported with the overlay2 graph driver on this kernel. Either boot into a newer kernel or disabl...nabled=false) #关键报错信息
Jun 22 15:22:45 registry.sefon.com systemd[1]: docker.service: main process exited, code=exited, status=1/FAILURE
Jun 22 15:22:45 registry.sefon.com systemd[1]: Failed to start Docker Application Container Engine.
Jun 22 15:22:45 registry.sefon.com systemd[1]: Unit docker.service entered failed state.
Jun 22 15:22:45 registry.sefon.com systemd[1]: docker.service failed.
Hint: Some lines were ellipsized, use -l to show in full.原因分析：
根据报错信息“Error starting daemon: SELinux is not supported with the overlay2 graph driver on this kernel. Either boot into a newer kernel or disabl...nabled=false)”的提示，这台机器的linux的内核中的SELinux不支持 overlay2 graph driver 。
解决方法有两个，要么启动一个新内核，要么就在docker配置文件里面里禁用selinux，--selinux-enabled=false
解决方法：
没有启动新的内核，修改的docker配置文件。将配置文件的“--selinux-enabled”改成“--selinux-enabled=false”，然后再重启docker。
[root@registry lib]# cat /etc/sysconfig/docker
# /etc/sysconfig/docker
# Modify these options if you want to change the way the docker daemon runs
#OPTIONS='--selinux-enabled --log-driver=journald --signature-verification=false'
OPTIONS='--selinux-enabled=false --log-driver=journald --signature-verification=false --registry-mirror=https://fzhifedh.mirror.aliyuncs.com --insecure-registry=registry.sese.com' #修改这里的"--selinux-enabled"，改成"--selinux-enabled=false"
if [ -z "${DOCKER_CERT_PATH}" ]; then
DOCKER_CERT_PATH=/etc/docker
fi
...... #配置文件后面的内容省略
[root@registry lib]# 然后重新启动docker，就正常启动了：
[root@registry lib]# systemctl start docker
[root@registry lib]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAME
[root@registry lib]#