Re: [PATCH v3] tracing: Fix rcu splat from idle CPU on boot.

From: Sebastian Andrzej Siewior
Date: Tue Dec 22 2015 - 09:47:01 EST


On 2015-12-14 11:07:09 [-0800], Philipp Schrader wrote:
> With PREEMPT_RT and most of the lockdep-related options enabled I
> encountered this splat when booting our DRA7 evaluation module:
>
> [ 0.055073]
> [ 0.055076] ===============================
> [ 0.055079] [ INFO: suspicious RCU usage. ]
> [ 0.055084] 4.1.6+ #2 Not tainted
> [ 0.055086] -------------------------------
> [ 0.055090] include/trace/events/hist.h:31 suspicious
> rcu_dereference_check() usage!
â
> As per Steve Rotstedt's suggestion I changed the trace_* calls to
> trace_*_rcuidle calls. He pointed out that the trace points were getting
> triggered when rcu wasn't watching.
>
> Signed-off-by: Philipp Schrader <philipp@xxxxxxxxxxxxxxxx>
> Acked-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>

I'm taking this for -RT. Is my assumption correct, that this goes into
the v4.5 merge window once everybody is back from holidays?

Sebastian
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