On Wed, Jun 26, 2019 at 11:49:16AM -0500, Scott Wood wrote: > On Wed, 2019-06-26 at 11:08 -0400, Steven Rostedt wrote: > > On Fri, 21 Jun 2019 16:59:55 -0700 > > "Paul E. McKenney" <paulmck@xxxxxxxxxxxxx> wrote: > > > > > I have no objection to the outlawing of a number of these sequences in > > > mainline, but am rather pointing out that until they really are outlawed > > > and eliminated, rcutorture must continue to test them in mainline. > > > Of course, an rcutorture running in -rt should avoid testing things that > > > break -rt, including these sequences. > > > > We should update lockdep to complain about these sequences. That would > > "outlaw" them in mainline. That is, after we clean up all the current > > sequences in the code. And we also need to get Linus's approval of this > > as I believe he was against enforcing this in the past. > > Was the opposition to prohibiting some specific sequence? It's only certain > misnesting scenarios that are problematic. The rcu_read_lock/ > local_irq_disable restriction can be dropped with the IPI-to-self added in > Paul's tree. Are there any known instances of the other two (besides > rcutorture)? Given the failure scenario Sebastian Siewior reported today, there apparently are some, at least when running threaded interrupt handlers. Thanx, Paul
