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Date: Tue, 29 Apr 2014 15:26:37 -0400
From: Steven Rostedt <rostedt@goodmis.org>
To: Vince Weaver <vincent.weaver@maine.edu>
Cc: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@kernel.org>,
        linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [perf] more perf_fuzzer memory corruption
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On Tue, 29 Apr 2014 14:21:56 -0400 (EDT)
Vince Weaver <vincent.weaver@maine.edu> wrote:
 
> Also trace-cmd is a pain to use.  Any suggested events I should trace 
> beyond the obvious?
> 
> Part of the problem is that despite what the documentation says it doesn't 
> look like you can combine the "-P pid" and "-c" children option, which 
> makes debugging a forking problem like this a lot harder to trace.

Yeah, I need kernel assistance to fix some of that.

> 
> It's sort of possible to get around that with a really complicated -F ""
> command line that does sudo back to me (don't want to fuzz as root) and 
> such, but still awkward.

I'll try to write up a patch that lets you use -P with -c. But due to
the (crappy) implementation with ptrace, trace-cmd needs to be a parent
of task.

In the mean time, you could run this as root:

 trace-cmd record -p function -F -c su non-root-user fuzz


-- Steve