Re: [BUG?] INFO: rcu_sched detected expedited stalls on CPUs/tasks: { 0-.... } 3 jiffies s: 309 root: 0x1/.

[Paul E. McKenney]

On Thu, Apr 13, 2023 at 04:32:32PM +0100, Rui Salvaterra wrote:
> Hi, Paul,
> 
> On Thu, 13 Apr 2023 at 15:43, Paul E. McKenney <paulmck@xxxxxxxxxx> wrote:
> >
> > My guess would be that you have CONFIG_RCU_EXP_CPU_STALL_TIMEOUT set to
> > some small non-zero number, for example, you might have set up a recent
> > Android .config or some such.  The default of zero would give you about
> > 21 seconds rather than the three jiffies that you are seeing.
> >
> > Could you please check your .config?
> 
> Well, this is embarrassing. I can't fathom why/how, but I had it set
> to 20, on this machine. That is, 20 millisseconds. I guess its a
> miracle I haven't seen *more* expedited RCU traces. Sorry for the
> noise, everyone.

Been there, done that!

And actually, it is kind of reassuring that the Linux kernel avoids
tens-of-milliseocnds latency blows in the common case on your system.

						Thanx, Paul