Re: [perf] perf_fuzzer causes crash in intel_pmu_drain_pebs_nhm()

[Vince Weaver]

On Thu, 11 Feb 2021, Liang, Kan wrote:

> > On Thu, Jan 28, 2021 at 02:49:47PM -0500, Vince Weaver wrote:
> I'd like to reproduce it on my machine.
> Is this issue only found in a Haswell client machine?
> 
> To reproduce the issue, can I use ./perf_fuzzer under perf_event_tests/fuzzer?
> Do I need to apply any parameters with ./perf_fuzzer?
> 
> Usually how long does it take to reproduce the issue?

On my machine if I run the commands
		echo 1 > /proc/sys/kernel/nmi_watchdog
                echo 0 > /proc/sys/kernel/perf_event_paranoid
                echo 1000 > /proc/sys/kernel/perf_event_max_sample_rate
                ./perf_fuzzer -s 30000 -r 1611784483

it is repeatable within a minute, but because of the nature of the fuzzer 
it probably won't work for you because the random events will diverge 
based on the different configs of the system.

I can try to generate a simple reproducer, I've just been extremely busy 
here at work and haven't had the chance.

If you want to try to reproduce it the hard way, run the
	./fast_repro99.sh
script in the perf_fuzzer directory.  It will start fuzzing.  My machine 
turned up the issue within a day or so.

Vince