Re: [PATCH 7/7] sparc64: Add function graph tracer support.

[Frederic Weisbecker <fweisbec@gmail.com>]

On Sat, Apr 17, 2010 at 02:38:37PM -0700, David Miller wrote:
> From: Frederic Weisbecker <fweisbec@gmail.com>
> Date: Sat, 17 Apr 2010 23:34:15 +0200
> 
> > I haven't started the watchdog nor perf, I guess NMI don't trigger
> > in other cases, right?
> 
> They do, for the NMI watchdog, every few seconds.
> 
> > For now, the only reentrancy I could find was irqs that interrupt
> > the tracing path. Which means no good clue there. That said I
> > have only logged recursivity on trace entry path, not yet
> > on return.
> > 
> > I'm disabling the protections on entry, just to narrow down
> > the recursivity place, in case it only happens on return.
> 
> No need to do so much work, when you hit this case simply
> disable tracing and dump_stack().  That way you'll see it
> clearly.



This is what I'm doing. But I needed to know where the tracing
recursion happens: on tracing entry or return.

And obviously it looks like that only happens on return. And
now I'm trying the dumps on return