Hello, Boqun, I have run overnight tests on your earlier branches here: ccb986e8b69f ("MAINTAINERS: Update Joel's email address") These passed other than a KCSAN complaint involving rcu_preempt_deferred_qs_handler() and rcu_read_unlock_special(). This looks like the plain C-language writes to ->defer_qs_iw_pending. My guess is that this is low probability, despite having happened twice, and that it happens when rcu_read_unlock_special() is interrupted, resulting in rcu_preempt_deferred_qs_handler() being invoked as an IRQ-work handler. Keeping in mind that RCU runs KCSAN so as to locate data races between task and handler on the same CPU. Thoughts? Thanx, Paul