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Date: Wed, 24 Aug 2016 19:44:17 -0400
From: "Emilio G. Cota" <cota@braap.org>
Message-ID: <20160824234417.GA16295@flamenco>
References: <CAFEAcA8KkT0rm4mMvrXrx_Gqqv8EXa4TDs=CT5XdOG0-FAyhcQ@mail.gmail.com>
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Subject: Re: [Qemu-devel] transient failure in the test-qht tests
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: QEMU Developers <qemu-devel@nongnu.org>

On Wed, Aug 24, 2016 at 21:39:01 +0100, Peter Maydell wrote:
> So I encountered this test failure running 'make check' on
> 32-bit ARM:
> 
> MALLOC_PERTURB_=${MALLOC_PERTURB_:-$((RANDOM % 255 + 1))} gtester -k
> --verbose -m=quick tests/test-qht
> TEST: tests/test-qht... (pid=15763)
>   /qht/mode/default:                                                   OK
>   /qht/mode/resize:                                                    FAIL
> GTester: last random seed: R02S08efd89fe4d862dd0191c13d5ce4d76e
> (pid=16462)
> FAIL: tests/test-qht
> 
> The test suite passed on a rerun.
> 
> Any ideas?

I wonder whether malloc perturb had to do with the failure, because
-ENOMEM is unlikely (I only see a few MB of peak mem usage for qht-test)

However, I just ran qht-test under valgrind on an i686 machine, and it comes
clean.

I also brute-forced this to see if a particular perturb value would
make it fail:
  for i in $(seq 0 255); do \
    echo $i && \
    MALLOC_PERTURB_=$i gtester -k --verbose -m=quick tests/test-qht \
    --seed=R02S08efd89fe4d862dd0191c13d5ce4d76e || break; \
  done

I get no failures on both i686 and x86_64, with and without that --seed flag.

Is there any chance of getting a core dump for the failure you encountered?

Thanks,

		Emilio