NMI during irq_interrupt() issue

[Stefan Scheler]

Hello,

I implemented a statistical profiler for fiasco using performance
monitoring counters (nmi handler is attached to handle_slow_trap()). It
works fairly well for "mathematical" workloads but as soon as interrupt
activity gets involved to a greater extent, the system freezes. For
example, keeping a button pressed while sampling will freeze the machine
within a few seconds. The NMI watchdog does not trigger during that
freeze. Higher sampling rates also cause these freezes.

So imho there seems to be a problem when irq_interrupt() or Irq::hit()
is interrupted by an NMI. What do you think? Any hints on how to fix
this or on how to debug this will be greatly appreciated.

Thanks in advance. I will happily provide further information if needed.

-- 
Stefan Scheler

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