Re: [PATCH] sched/debug: avoid executing show_state and causing rcu stall warning

[Ingo Molnar]

* Paul E. McKenney <paulmck@xxxxxxxxxx> wrote:

> There is an rcu_sysrq_start() and rcu_sysrq_end() to suppress this.  
> These are invoked by __handle_sysrq().  The value of 
> rcu_cpu_stall_suppress should be non-zero during the sysrq execution, and 
> this should prevent RCU CPU stall warnings from being printed.
> 
> That said, the code currently does not support overlapping calls to the 
> various functions that suppress RCU CPU stall warnings.  Except that the 
> only other use in current mainline is rcu_panic(), which never 
> unsuppresses.
> 
> So could you please check the value of rcu_cpu_stall_suppress? Just in 
> case some other form of suppression was added somewhere that I missed?

So instead of supressing the (justified!) RCU stall messages, I'd much 
rather we apply only the minimal locking necessary for this debug printout.

That should also solve the stall warnings as a side effect.

Thanks,

	Ingo