On Tue, Dec 01, 2020 at 07:15:06PM +0100, Peter Zijlstra wrote: > On Tue, Dec 01, 2020 at 03:55:19PM +0100, Peter Zijlstra wrote: > > On Tue, Dec 01, 2020 at 06:46:44AM -0800, Paul E. McKenney wrote: > > > > > > So after having talked to Sven a bit, the thing that is happening, is > > > > that this is the one place where we take interrupts with RCU being > > > > disabled. Normally RCU is watching and all is well, except during idle. > > > > > > Isn't interrupt entry supposed to invoke rcu_irq_enter() at some point? > > > Or did this fall victim to recent optimizations? > > > > It does, but the problem is that s390 is still using > > I might've been too quick there, I can't actually seem to find where > s390 does rcu_irq_enter()/exit().
Argh, do_IRQ is per arch.. and that does irq_enter() which then does the deed (thanks Sven!).