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Re: perf: fuzzer crashes immediately on AMD system

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On Fri, 19 Aug 2016, Peter Zijlstra wrote:

> On Thu, Aug 18, 2016 at 10:46:31AM -0400, Vince Weaver wrote:
> > On Thu, 18 Aug 2016, Vince Weaver wrote:
> > 
> > > Tried the perf_fuzzer on my A10 fam15h/model13h system with 4.8-rc2 and it
> > > falls over more or less immediately.
> > > 
> > > This maps to variable_test_bit()
> > > 	called by ctx = find_get_context(pmu, task, event);
> > > 		in kernel/events/core.c:9467
> > > 
> > > It happens quickly enough I can probably track down the exact event that 
> > > causes this, if needed.
> > 
> > I have a one line reproducer:
> > 
> > 	perf stat -a -e amd_nb/config=0x37,config1=0x20/ /bin/ls
> 
> OK, cannot reproduce on my fam15h/model1h. I'll go dig through the
> various manuals to see if I can spot the fail.
> 
> Huang could you either prod someone at AMD or do yourself, audit the AMD
> perf code for all the various new models?


OK, this is weird.  I rebooted (didn't patch the kernel, just rebooted) 
and I can't reproduce the original problem at all.

It was perfectly repeatable before I rebooted, dumped an OOPS message 
every time.

Sadly I don't have the fuzzer logs that originally triggered the bug (need 
more serial/USB cables.  Actually no, I need more null-modem adapters).

Let me look into this a bit more.

Vince

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Re: perf: fuzzer crashes immediately on AMD system Vince Weaver <vincent.weaver@maine.edu> - 2016-08-18 16:50 +0200
  Re: perf: fuzzer crashes immediately on AMD system Peter Zijlstra <peterz@infradead.org> - 2016-08-19 12:10 +0200
    Re: perf: fuzzer crashes immediately on AMD system Peter Zijlstra <peterz@infradead.org> - 2016-08-19 13:00 +0200
    Re: perf: fuzzer crashes immediately on AMD system Vince Weaver <vincent.weaver@maine.edu> - 2016-08-19 17:10 +0200
      Re: perf: fuzzer crashes immediately on AMD system Vince Weaver <vincent.weaver@maine.edu> - 2016-08-19 18:40 +0200
    Re: perf: fuzzer crashes immediately on AMD system Vince Weaver <vincent.weaver@maine.edu> - 2016-08-20 06:50 +0200
    Re: perf: fuzzer crashes immediately on AMD system Vince Weaver <vincent.weaver@maine.edu> - 2016-08-23 03:20 +0200
      Re: perf: fuzzer crashes immediately on AMD system Vince Weaver <vincent.weaver@maine.edu> - 2016-08-23 05:00 +0200
        Re: perf: fuzzer crashes immediately on AMD system Peter Zijlstra <peterz@infradead.org> - 2016-08-23 10:50 +0200
          Re: perf: fuzzer crashes immediately on AMD system Vince Weaver <vincent.weaver@maine.edu> - 2016-08-23 14:10 +0200
            Re: perf: fuzzer crashes immediately on AMD system Ingo Molnar <mingo@kernel.org> - 2016-08-24 11:30 +0200
              Re: perf: fuzzer crashes immediately on AMD system Vince Weaver <vincent.weaver@maine.edu> - 2016-08-24 15:30 +0200

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