Messages in this thread | | | Subject | Re: [PATCH tip/core/rcu 11/15] rcu: Avoid spurious RCU CPU stall warnings | From | Steven Rostedt <> | Date | Fri, 07 Sep 2012 10:42:09 -0400 |
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On Fri, 2012-09-07 at 09:00 +0200, Peter Zijlstra wrote: > On Thu, 2012-09-06 at 15:22 -0700, Paul E. McKenney wrote: > > Ah! > > > > It is perfectly legal to avoid -starting- an RCU grace period for a > > minute, or even longer. If RCU has nothing to do, in other words, if no > > one registers any RCU callbacks, then RCU need not start a grace period. > > > > Of course, this would mean that it would eventually be a full minute > > since the last start of a grace period. This is not a problem, after > > all, Linux went through a full ten years before experiencing its first > > grace period. > > > > But the stall-warning code just checked how long it had been since > > the last start of a grace period, failing to note that this grace > > period had long since completed. So it splatted out a warning. > > This warning was spurious in the sense that there was no bug aside > > from the missing check that the grace period was still in progress. > > > > And this commit fixes that bug in RCU. > > OK, that makes sense.. it just looks like both Steve and me got confused > by the initial changelog.
Right, I think the change log needs to be fixed ;-)
-- Steve
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