Docker commands frozen on an openshift node

Issue

• Docker got frozen on the node. All "docker" commands were waiting forever. -
• Openshift displayed the node as "NotReady" and all pods went to "Unknown state"
• systemctl stop docker was also frozen
• kill on docker processes did nothing
• kill -9 on docker processes kill most of them but we had some processes (mainly "du" commands) which were not possible to kill
• docker command was still frozen after killing the processes