Re: [paulmck-rcu:dev.2023.11.08a] [EXP locktorture] 1254a620b4: WARNING:at_kernel/rcu/tree_stall.h:#rcu_stall_chain_notifier_register

From: Oliver Sang
Date: Mon Dec 11 2023 - 21:06:57 EST


hi, Paul,

On Mon, Dec 11, 2023 at 08:59:16AM -0800, Paul E. McKenney wrote:
> On Thu, Dec 07, 2023 at 04:19:56PM +0800, kernel test robot wrote:
> >
> >
> > Hello,
> >
> > kernel test robot noticed "WARNING:at_kernel/rcu/tree_stall.h:#rcu_stall_chain_notifier_register" on:
> >
> > commit: 1254a620b4a3832e65ac01bcef769b99e34515b2 ("EXP locktorture: Add RCU CPU stall-warning notifier stub")
> > https://git.kernel.org/cgit/linux/kernel/git/paulmck/linux-rcu.git dev.2023.11.08a
>
> Thank you for your testing efforts!
>
> This one is expected behavior by explicit request from Linus Torvalds.
> The concern is that people might use this hook without understanding
> the risks of losing RCU CPU stall warnings.
>
> One fix would be to never specify the rcupdate.rcu_cpu_stall_notifiers
> kernel boot parameter. Another would be to forgive this warning when
> that boot parameter was specified. Your choice! ;-)
>
> Thanx, Paul

Thanks a lot for information!

this commit (1254a620b4) is a test for this warning, am I right?
when this warning mechanism goes into upstream, do you want us still report
for similar cases? or we could just ignore them? Thanks!