rhel7: fencing via IPMI does not work, only results in "kernel:Uhhuh. NMI received for unknown reason 3d on CPU 0."

Issue

When fencing with fence_ipmilan -i <BMC-IPaddr> -l <login> -p <pass> -o diag or directly with ipmitools then the target host does not reboot but instead only logs this:

Message from syslogd@host at Jun 18 16:44:06 ...
 kernel:Uhhuh. NMI received for unknown reason 3d on CPU 0.

Message from syslogd@host at Jun 18 16:44:06 ...
 kernel:Do you have a strange power saving mode enabled?

Message from syslogd@host at Jun 18 16:44:06 ...
 kernel:Dazed and confused, but trying to continue

This worked until (including) RHEL7RC1, but after that not.