Messages in this thread | ![/](/images/icornerl.gif) | | Date | Mon, 11 Feb 2008 10:37:33 -0500 | From | Steven Rostedt <> | Subject | Re: preempt rcu bug on s390 |
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Heiko Carstens wrote:
>> Does s390 start out in nohz mode? The reason I ask is that it feels like >> an off-by-one error for the dynticks_progress_counter. > > Actually I forgot to add a few ifdefs to make the code do something :) > That just reveals that we have a conflict with the dynticks implementation > and s390's nohz that shows up in what rcu_irq_enter/exit assume. > I didn't patch s390 and common code so it will work, but I think the > patch you mentionened will fix the problem I reported. > So I guess we should either convert s390 to use the generic dynticks > implementation or disable preemptible rcu on s390 until we converted > our code. > > Thanks for helping debugging this!
Heiko, thanks for reporting this.
This patch still didn't make it into -rc1, and it really should. Because without this patch, PREEMPT_RCU and NO_HZ together is broken, on all boxes.
The patch is in Ingo's sched-devel git tree, as 9460545f81ea48b07dbb20456a8ede776d8ebc1b (last I checked) and titled:
rcu: add support for dynamic ticks and preempt rcu
-- Steve
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