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

Vince Weaver
2021-02-11T22:15:40Z

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