腾讯云服务器启动lightdm遇到“Active: failed (Result: start-limit)”错误解决方法

我在腾讯云服务器上安装图形界面，在启动lightdm时失败了：
[root@VM_0_11_centos gdm]# systemctl start lightdm
[root@VM_0_11_centos gdm]# systemctl status lightdm
● lightdm.service - Light Display Manager
   Loaded: loaded (/usr/lib/systemd/system/lightdm.service; enabled; vendor preset: enabled)
   Active: failed (Result: start-limit) since Sat 2020-04-04 12:02:18 CST; 6s ago
     Docs: man:lightdm(1)
  Process: 8495 ExecStart=/usr/sbin/lightdm (code=exited, status=1/FAILURE)
 Main PID: 8495 (code=exited, status=1/FAILURE)

Apr 04 12:02:17 VM_0_11_centos systemd[1]: Unit lightdm.service entered failed state.
Apr 04 12:02:17 VM_0_11_centos systemd[1]: Triggering OnFailure= dependencies of lightdm.service.
Apr 04 12:02:17 VM_0_11_centos systemd[1]: lightdm.service failed.
Apr 04 12:02:18 VM_0_11_centos systemd[1]: lightdm.service holdoff time over, scheduling restart.
Apr 04 12:02:18 VM_0_11_centos systemd[1]: Stopped Light Display Manager.
Apr 04 12:02:18 VM_0_11_centos systemd[1]: start request repeated too quickly for lightdm.service
Apr 04 12:02:18 VM_0_11_centos systemd[1]: Failed to start Light Display Manager.
Apr 04 12:02:18 VM_0_11_centos systemd[1]: Unit lightdm.service entered failed state.
Apr 04 12:02:18 VM_0_11_centos systemd[1]: Triggering OnFailure= dependencies of lightdm.service.
Apr 04 12:02:18 VM_0_11_centos systemd[1]: lightdm.service failed.

解决方法：
原因是libdrm版本太低了，所以更新就行了。
[root@VM_0_11_centos ~]# yum update libdrm
[root@VM_0_11_centos ~]# systemctl start lightdm
[root@VM_0_11_centos ~]# systemctl status lightdm
● lightdm.service - Light Display Manager
   Loaded: loaded (/usr/lib/systemd/system/lightdm.service; enabled; vendor preset: enabled)
   Active: active (running) since Sat 2020-04-04 22:21:33 CST; 6s ago
   。。。

我的云服务器实例类型是标准型SA1，centos 7.5 64位系统。