quoted

I've not been able to reproduce it since, but I know others (BCC'ed on
this note) have seen it and might prod them to come forth with details
(and broken .config files)

In my case, disabling CPU_FREQ_PMAC made the failure go away.
After reverting this patch, CPU_FREQ_PMAC is once again operating
successfully, so far.

Hrm.. which cpufreq method is used on both your machines ? If it's the
one involving the PMU, it does involve a full hard reset of the
processor (with appropriate cache flushes etc...), maybe something's
going wrong in that area....

Ben.