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Message-ID: <alpine.DEB.2.10.1310241422460.6573@vincent-weaver-1.um.maine.edu>
Date: Thu, 24 Oct 2013 14:25:06 -0400 (EDT)
From: Vince Weaver <vincent.weaver@...ne.edu>
To: linux-kernel@...r.kernel.org
cc: Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
Dave Jones <davej@...hat.com>,
Steven Rostedt <rostedt@...dmis.org>,
Frederic Weisbecker <fweisbec@...il.com>
Subject: Re: perf/ftrace lockup on 3.12-rc6 with trigger code
On Thu, 24 Oct 2013, Vince Weaver wrote:
> after a month of trying I finally got a small test-case out of my
> perf_fuzzer suite that triggers a system lockup with just one syscall.
>
> Attached is the code that triggers it.
And it turns out you can only trigger this specific problem if advanced
ftrace options are enabled.
CONFIG_KPROBES_ON_FTRACE=y
CONFIG_FUNCTION_TRACER=y
CONFIG_FUNCTION_GRAPH_TRACER=y
CONFIG_STACK_TRACER=y
CONFIG_DYNAMIC_FTRACE=y
CONFIG_DYNAMIC_FTRACE_WITH_REGS=y
CONFIG_FUNCTION_PROFILER=y
CONFIG_FTRACE_MCOUNT_RECORD=y
Urgh, I had turned those on to try to debug something and forgot to
disable. I feel like I saw this problem before I had those enabled so I
guess I have to start from scratch fuzzing to see if I can get a more
generally reproducible trace.
Vince
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