linux-kernel - Re: [PATCHv2 1/2] tracing - fix recursive user stack trace

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Date:	Thu, 11 Nov 2010 11:34:15 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Jiri Olsa <jolsa@...hat.com>
Cc:	mingo@...e.hu, rostedt@...dmis.org, andi@...stfloor.org,
	lwoodman@...hat.com, hch@...radead.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCHv2 1/2] tracing - fix recursive user stack trace

On Thu, Nov 11, 2010 at 10:09:08AM +0100, Jiri Olsa wrote:
> The user stack trace can fault when examining the trace. Which
> would call the do_page_fault handler, which would trace again,
> which would do the user stack trace, which would fault and call
> do_page_fault again ...
> 
> Thus this is causing a recursive bug. We need to have a recursion
> detector here.

I suspect this problem is in more trace points: any NMI or MCE 
trace point or any other trace point that can be triggered
from a page. so it seems to be a general bug fix independent
of the other patch.

-Andi
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