Messages in this thread | | | Date | Thu, 30 Jun 2016 10:52:16 -0700 | From | "Paul E. McKenney" <> | Subject | Re: rcu_preempt self-detected stall on CPU from 4.5-rc3, since 3.17 |
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On Sat, May 07, 2016 at 08:25:01AM -0700, Paul E. McKenney wrote: > On Fri, May 06, 2016 at 04:25:16PM +1000, Ross Green wrote: > > On Sun, Apr 3, 2016 at 6:18 PM, Paul E. McKenney > > <paulmck@linux.vnet.ibm.com> wrote:
[ . . . ]
> > Thought i would update a few runs with the linux-4.6-rc kernels. > > > > I have attached log outputs through dmesg showing rcu_preempt stall warnings. > > > > > > Thought it might be interesting for someone else to look at. > > > > Currently running linux-4.6-rc6 in testing. > > Thank you for sending these, I will look them over! > > Still working to reproduce this quickly enough to do real debug... :-/
And Peter Zijlstra's patch looks to have hugely reduced the rate of occurrence of this bug in my testing:
lkml.kernel.org/r/20160523091907.GD15728@worktop.ger.corp.intel.com
Almost all of the issues I am seeing now are transient, do not trigger RCU CPU stall warnings, and would not have been visible to me before I upgraded my testing scripts and in-kernel code. In all the tests I have run with Peter's fix, I have seen only one run with RCU CPU stall warnings, and all the stalls in that run were transient, unlike those that I was seeing before his fix.
I will of course be tracking this stuff down, but the low reproduction rates will make it slow going.
I am guessing that you no longer see this issue?
Thanx, Paul
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