Re: Lockup in tracepoint unregister in sched switch ftrace plugin

[Ingo Molnar]

* Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:

> [ Paul, Thomas, wake up ]
> 
> On Mon, 20 Oct 2008, Steven Rostedt wrote:
> > 
> >   which calls unregister_trace_sched_switch define as macro to:
> > 
> > kernel/tracepoint.c: tracepoint_probe_unregister
> >    " "  : remove_tracepoint
> > kernel/rcupdate.c: rcu_barrier_sched
> >    " "  : _rcu_barrier
> > 
> > where it gets stuck at that "wait_for_completion".
> > 
> > I'm not sure if, because this is a scheduler trace point that we are 
> > hitting some kind of race that is preventing the wait_for_completion to 
> > finish, or what.
> 
> Note, I just booted this kernel with CONFIG_NOHZ=n and it booted fine. 
> This looks like a bug somewhere in tracepoints/RCU/dynamic-ticks

does it work with fb02fbc14 reverted? (see the reverter patch below or 
try tip/master)

	Ingo

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