Subject: RCU lockup issues when CONFIG_SOFTLOCKUP_DETECTOR=n - any one else seeing this?

From: [email-masked] (Paul E. McKenney)
Date: Sun, 30 Jul 2017 09:59:01 -0700

On Sun, Jul 30, 2017 at 09:37:47PM +0800, Boqun Feng wrote:
> On Fri, Jul 28, 2017 at 12:09:56PM -0700, Paul E. McKenney wrote:
> > On Fri, Jul 28, 2017 at 11:41:29AM -0700, Paul E. McKenney wrote:
> > > On Fri, Jul 28, 2017 at 07:55:30AM -0700, Paul E. McKenney wrote:
> > > > On Fri, Jul 28, 2017 at 08:54:16PM +0800, Boqun Feng wrote:
> > 
> > [ . . . ]
> > 
> > > > Even though Jonathan's testing indicates that it didn't fix this
> > > > particular problem:
> > > > 
> > > > Acked-by: Paul E. McKenney <[email-masked]>
> > > 
> > > And while we are at it:
> > > 
> > > Tested-by: Paul E. McKenney <[email-masked]>
> > 
> > Not because it it fixed the TREE01 issue -- it did not.  But as near
> > as I can see, it didn't cause any additional issues.
> > 
> 
> Understood.
> 
> Still work on waketorture for a test case which could trigger this
> problem in a real world. My old plan is to send this out when I could
> use waketorture to show this patch actually resolves some potential
> bugs, but just put it ahead here in case it may help.
> 
> Will send it out with your Tested-by and Acked-by and continue to work
> on waketorture.

Sounds good!

Given that Jonathan's traces didn't show a timer expiration, the problems
might be in timers.

							Thanx, Paul