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

Liang, Kan
2021-02-25T20:17:45Z

On 2/11/2021 5:14 PM, Vince Weaver wrote:
> 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.
>
Sorry for the late response. Just want to let you know I'm still trying
to reproduce the issue.

I only have a Haswell server on hand. I run the ./fast_repro99.sh on the
machine for 3 days, but I didn't observe any crash.
Now, I'm looking for a HSW client in my lab. I will check if I can
reproduce it on a client machine.

If you have a simple reproducer, please let me know.

Thanks,
Kan