Date: Mon, 16 Feb 2015 13:34:47 -0500
From: Steven Rostedt <rostedt@goodmis.org>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>, Huang Ying <ying.huang@intel.com>,
        Ingo Molnar <mingo@kernel.org>, LKML <linux-kernel@vger.kernel.org>,
        LKP ML <lkp@01.org>
Subject: Re: [LKP] [sched] BUG: kernel boot hang
Message-ID: <20150216133447.50135132@gandalf.local.home>
In-Reply-To: <20150216182235.GA20614@lerouge>
References: <1423986208.5538.5.camel@intel.com>
	<20150215154620.GC8838@lerouge>
	<20150215131807.30c1808c@grimm.local.home>
	<20150216150733.GD5029@twins.programming.kicks-ass.net>
	<20150216182235.GA20614@lerouge>
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On Mon, 16 Feb 2015 19:22:38 +0100
Frederic Weisbecker <fweisbec@gmail.com> wrote:
 
> Huang Ying hasn't yet reported a Tested-by but I could reproduce (with both function and function_graph tracers btw)
> and the patch fixed it.

Ah right, it's not the recursion from the function tracer that kills
us, it's the recursion from the preempt_enable_notrace() that does...

preempt_schedule_common()
  --> traced
     preempt_disable_notrace();
     preempt_enable_notrace();
     (see's NEED_RESCHED set)
	preempt_schedule_context();
	    preempt_schedule_common();
		--> traced

etc, etc till boom.

-- Steve

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