Hot plug/unplug of pmem memory can cause kernel panic on POWER9

Environment

*Red Hat Enterprise Linux (RHEL) 8.2

Issue

Hot plugging/unplugging of pmem memory on IBM POWER9 systems,
which has a size that is not in multiples of the expected granularity can lead to kernel panics.

On PPC64LE this issue will usually manifest itself as a kernel panic seen bwhen trying to create or destroy namespaces, which sizes are not in multiples of 16MiB.

Resolution

This is a known issue. It is being tracked under Red Hat Private Bugzilla 1808344. Open a service ticket for more information on it through the Red Hat Customer Portal.

To workaround this issue ensure that any namespaces created are in multiples of 16MiB.

Root Cause

The kernel memory hotplug subsystem expects the memory to be added in specific granularities, depending on the architecture.

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