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Subject: Re: [perf] perf_fuzzer causes crash in intel_pmu_drain_pebs_nhm()
To:     Vince Weaver <vincent.weaver@maine.edu>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@redhat.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Stephane Eranian <eranian@google.com>
References: <61a56699-aab4-ef6-ed8d-a22b6bf532d@maine.edu>
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 <YCVE8q4MlbcU4fnV@hirez.programming.kicks-ass.net>
 <d2005608-4214-ec01-d6b1-a7d19fab7bf9@linux.intel.com>
 <2a655469-de9d-c80-dd7f-26436d6f03a@maine.edu>
From:   "Liang, Kan" <kan.liang@linux.intel.com>
Message-ID: <9b3f84e0-e1cc-cebe-43b6-fa062484ad28@linux.intel.com>
Date:   Thu, 25 Feb 2021 15:15:26 -0500
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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