On Tue, Oct 20, 2015 at 05:32:28PM -0400, Steven Rostedt wrote:
> On Tue, 20 Oct 2015 13:25:28 -0700
> "Paul E. McKenney" <[email protected]> wrote:
>
> > On Tue, Oct 20, 2015 at 12:10:31PM -0400, Steven Rostedt wrote:
> > >
> > > Paul,
> > >
> > > I've spent a couple of days debugging this, and finally found that my
> > > stack tracer was calling the stack trace code, which calls
> > > __module_address() which asserts the below.
> > >
> > > Is just calling rcu_irq_enter() and rcu_irq_exit() safe to do
> > > everywhere (with interrupts always disabled)? This patch appears to fix
> > > the bug.
> >
> > Yep! Just don't call it from an NMI handler. And don't call it with
> > interrupts enabled. The patch looks to have interrupts always disabled,
> > and the surrounding code doesn't look like NMI-safe code anyway, so
> > should be OK.
> >
> > Thanx, Paul
> >
>
> Hmm, good point about NMI handler. Right now I think the only thing
> protecting this from getting in the critical section while in NMI is
> the check that we are using the task struct stack. But that may not be
> enough in 32 bit.
>
> I should probably add a "if (in_nmi()) return" somewhere.
Please! ;-) ;-) ;-)
Thanx, Paul
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
