From mboxrd@z Thu Jan  1 00:00:00 1970
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: Re: 4.8.6-rt5 ftrace function_graph hangs
Date: Tue, 6 Dec 2016 12:07:15 +0100
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Cc: He Zhe <zhe.he@windriver.com>,
        Steven Rostedt <rostedt@goodmis.org>, tglx@linutronix.de,
        linux-rt-users@vger.kernel.org
To: Yang Shi <yang.shi@windriver.com>
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On 2016-12-02 13:42:06 [-0800], Yang Shi wrote:
> Hi Sebastian,
Hi Yang,

> Thanks for following up. I had been distracted by something else. And, I did
> more testing, then I narrowed it down to ARM and PPC only.
okay.

> In addition, I narrowed it down to CONFIG_DEBUG_PREEMPT. function_graph
> tracer works well with it disabled on ARM and PPC. But, I haven't got time
> to figure out why.

It could be a warning that comes with CONFIG_DEBUG_PREEMPT triggers once
function_graph gets enabled. This warning in turn could cause another
warning or go for another reason recursive.

> Yang
> 
Sebastian