NetworkPlugin cni failed to set up after rebooting host

Issue

• After rebooting hosts, some pods become CrashLoopBackOff with following event logs:

Events:
  Type     Reason                  Age                From                                                                     Message
  ----     ------                  ----               ----                                                                     -------
  Warning  FailedCreatePodSandBox  25m                kubelet, xxxx        Failed create pod sandbox: rpc error: code = Unknown desc = failed to set up sandbox container "4d71d3d2b47f493df9914f4e50618c6720c9a9ab29538d01184f4060cc8e871b" network for pod "logging-fluentd-7z82p": NetworkPlugin cni failed to set up pod "logging-fluentd-7z82p_openshift-logging" network: OpenShift SDN network process is not (yet?) available
  Warning  NetworkFailed           25m                openshift-sdn, xxxx  The pod's network interface has been lost and the pod will be stopped.
  Warning  FailedCreatePodSandBox  25m                kubelet, xxxx        Failed create pod sandbox: rpc error: code = Unknown desc = failed to set up sandbox container "9ee7eef850bcfa1fd4eb85e3ca16221ed2db255f5edfb249fbc4a129078c174d" network for pod "logging-fluentd-7z82p": NetworkPlugin cni failed to set up pod "logging-fluentd-7z82p_openshift-logging" network: failed to Statfs "/proc/12548/ns/net": no such file or directory

• How to fix it?