Re: Lockup in tracepoint unregister in sched switch ftrace plugin
From: Paul E. McKenney
Date: Tue Oct 21 2008 - 12:18:41 EST
On Tue, Oct 21, 2008 at 12:14:03AM -0400, Steven Rostedt wrote:
> [ Paul, Thomas, wake up ]
I am awake, but fortunately for me, Ingo woke up before I did. ;-)
(Sorry, couldn't resist...)
> 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
> -- Steve
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