linux-kernel - perf: overflow signal survives an exec call starting in 3.0

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Message-ID: <alpine.DEB.2.00.1108231127380.30837@cl320.eecs.utk.edu>
Date:	Tue, 23 Aug 2011 11:36:10 -0400
From:	Vince Weaver <vweaver1@...s.utk.edu>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
CC:	<linux-kernel@...r.kernel.org>, <mingo@...e.hu>,
	<paulus@...ba.org>, <acme@...stprotocols.net>,
	Stephane Eranian <eranian@...il.com>, <krentel@...rice.edu>
Subject: perf: overflow signal survives an exec call starting in 3.0

Hello

Mark Krentel noticed that starting with Linux 3.0 perf_event signals
survive a call to exec().  

This means that if you exec() from within a perf-monitored process
and don't immediately start a signal handler, your process will
quickly be killed with a SIGIO signal.

I'm guessing this was an unintended change, although what to do in
this situation is a bit vague.

I tediously bisected this to the following commit:

commit f506b3dc0ec454a16d40cab9ee5d75435b39dc50
Author: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Date:   Thu May 26 17:02:53 2011 +0200

    perf: Fix SIGIO handling

Attached is an example program that exhibits the problem.

Vince

View attachment "signal_after_exec.c" of type "text/x-csrc" (3036 bytes)