Child process exited with code 1 during RHOCP cluster upgrade

Customers running OpenShift may have installed OpenShift 4 Machine Config for Gremlin Chaos Engineering Platform  (gremlin-ocp4-mc)

This machine operator was necessary for older versions of OpenShift (4.1 - 4.6)

The Gremlin machine operator is no longer required and should be removed from all nodes within the cluster.

$ oc get mc/96-worker-gremlin-semodule > /tmp/96-worker-gremlin-semodule_backup.yaml. --->  it will create backup of mc in /tmp directory

$ oc delete mc/96-worker-gremlin-semodule

    For OpenShift, whenever hostPID=true, custom SELinux policies are ignored in favor of using the spc_t process label. In short, when hostPID=true, Gremlin does not need any custom SELinux policies.

    Earlier versions of Gremlin allowed for some functionality to work when hostPID=false, and we even would install with this set to false by default in favor of using the least amount of privileges possible. Over time, the need for always setting hostPID=true became obvious for us to accomplish all of the container targeting features reliably (especially with the removal of runc). 

    Today, we consider hostPID=true a requirement for container attacks on any platform and as a result no longer have a need for custom SELinux profiles on OpenShift.

RedHat has a KB article about this as well. Gremlin customers should just remove this machine operator before upgrading their RHOCP clusters