On Mon, 8 May 2017 15:43:33 -0500
Josh Poimboeuf <jpoim...@redhat.com> wrote:
> Ok, so just to clarify. Is there a bug in the ftrace stack tracer in
> the following situation?
>
> 1. RCU isn't watching
> 2. An NMI hits
> 3. ist_enter() calls into the ftrace stack tracer, before
> rcu_nmi_enter() is called, so RCU isn't watching yet
No, because in the ftrace stack tracer there's:
if (in_nmi())
return;
At the very beginning.
-- Steve
> 4. The ftrace stack tracer calls rcu_irq_enter(), which has no effect,
> so RCU still isn't watching
> 5. Hilarity ensues in the ftrace stack tracer
>
