Re: [BUG] srcu: false-positive WARN in cleanup_srcu_struct() after 78a38cbf6f20

[Sunho Park <shpark061104@gmail.com>]

On 8/27/26 21:40, Zqiang wrote:
> Now, I am trying to rephrase your problem in the following way:
> 
> 1- the step1 call_srcu() trigger SRCU grace period has been end and queue sdp->work.
> 2- the step4 queue srcu callback has been intercepted by step5 srcu_barrier()
>     and start a new SRCU grace period.
> 3- this new SRCU grace period end, and invoke rcu_seq_end(&sup->srcu_gp_seq), queue a timer.
> 4- the sdp->work begin run, and call srcu_segcblist_advance() with current sup->srcu_gp_seq.
>     so the step4's srcu callback and step5's barrier calback both to be run.
>     all callback finished, but the len not yet update.
> 5- the srcu_barrier() return, begin call srcu_clean_up(), and then the srcu_clean_up
>     find the a timer is still pending and the cb_len also not be zero, trigger WARN_ON()
> 
> right?
Exactly. The real callbacks are properly invoked as srcu_barrier() 
guarantees. The WARN is triggered only by the two transient states: a 
pending delay_work timer and a stale cblist len. So I think this is a 
false positive warning.

Sorry if my explanations were too wordy.

Thanks
Sunho Park