linux-kernel - Re: [perf] perf_fuzzer causes crash in intel_pmu_drain_pebs

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Message-ID: <2a655469-de9d-c80-dd7f-26436d6f03a@maine.edu>
Date:   Thu, 11 Feb 2021 17:14:50 -0500 (EST)
From:   Vince Weaver <vincent.weaver@...ne.edu>
To:     "Liang, Kan" <kan.liang@...ux.intel.com>
cc:     Peter Zijlstra <peterz@...radead.org>,
        Vince Weaver <vincent.weaver@...ne.edu>,
        linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Stephane Eranian <eranian@...gle.com>
Subject: Re: [perf] perf_fuzzer causes crash in intel_pmu_drain_pebs_nhm()

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