On Fri, Sep 13, 2024 at 11:00:39AM -0700, Paul E. McKenney wrote: > On Fri, Sep 13, 2024 at 06:55:34PM +0200, Valentin Schneider wrote: > > On 13/09/24 07:08, Paul E. McKenney wrote: > > > On Sun, Sep 08, 2024 at 09:32:18AM -0700, Paul E. McKenney wrote: > > >> > > >> Just following up... > > >> > > >> For whatever it is worth, on last night's run of next-20240906, I got > > >> nine failures out of 100 6-hour runs of rcutorture’s TREE03 scenario. > > >> These failures were often, but not always, shortly followed by a hard hang. > > >> > > >> The warning at line 1995 is the WARN_ON_ONCE(on_dl_rq(dl_se)) > > >> in enqueue_dl_entity() and the warning at line 1971 is the > > >> WARN_ON_ONCE(!RB_EMPTY_NODE(&dl_se->rb_node)) in __enqueue_dl_entity(). > > >> > > >> The pair of splats is shown below, in case it helps. > > > > > > Again following up... > > > > > > I am still seeing this on next-20240912, with six failures out of 100 > > > 6-hour runs of rcutorture’s TREE03 scenario. Statistics suggests that > > > we not read much into the change in frequency. > > > > > > Please let me know if there are any diagnostic patches or options that > > > I should apply. > > > > Hey, sorry I haven't forgotten about this, I've just spread myself a bit > > too thin and also apparently I'm supposed to prepare some slides for next > > week, I'll get back to this soonish. > > I know that feeling! Just didn't want it to get lost. And Peter asked that I send along a reproducer, which I am finally getting around to doing: tools/testing/selftests/rcutorture/bin/kvm.sh --allcpus --duration 12h --configs "100*TREE03" --trust-make Note that this run will consume 19,200 CPU hours, or almost two CPU years. Therefore, this is best done across a largish number of systems. The kvm-remote.sh script can be helpful for this sort of thing, and you give it a quoted list of systems before the rest of the arguments shown above. Doing this on a -next from last week got me 15 failures similar to the following: [41212.683966] WARNING: CPU: 14 PID: 126 at kernel/sched/deadline.c:1995 enqueue_dl_entity+0x511/0x5d0 [41212.712453] WARNING: CPU: 14 PID: 126 at kernel/sched/deadline.c:1971 enqueue_dl_entity+0x54f/0x5d0 Thanx, Paul
