On Thu, Jul 10, 2008 at 01:41:57PM -0700, Paul E. McKenney wrote: > On Thu, Jul 10, 2008 at 08:06:20PM +0200, Ingo Molnar wrote: > > > > * Ingo Molnar <mingo@xxxxxxx> wrote: > > > > > cool! :) > > > > > > (hm, could anyone please resend Nick's original mail? The original one > > > is not in my lkml folder nor on lkml.org - only the quoted one.) > > > > ok, got the mail now now: > > > > | | Annoyed this wasn't a crazy obscure error in the algorithm I could > > | | fix :) [...] > > > > Paul recently ran a formal proof against all sorts of RCU details (and > > found and fixed a few obscure races that way that no-one ever > > triggered), so i'd be quite surprised if we found anything in the core > > algorithm :-) Yeah, it was instead the simple stuff that I messed up... :-/ > > | | [...] I spent all day debugging it and had to make a special test > > | | case (rcutorture didn't seem to trigger it), and a big RCU state > > | | logging infrastructure to log millions of RCU state transitions and > > | | events. Oh well. > > > > nice debugging! > > Indeed!!! > > > Acked-by: Ingo Molnar <mingo@xxxxxxx> > > > > i'm wondering why rcutorture didnt trigger it. I do run !HOTPLUG + > > RCU_PREEMPT kernels and never saw this. Nor did Paul. That aspect is > > weird. > > Turns out that my environment was silently re-enabling HOTPLUG_CPU, so I > only -thought- I was testing !CPU_HOTPLUG. Once I forced it to really > disable HOTPLUG_CPU (by manually also specifying CONFIG_SUSPEND=n and > CONFIG_HIBERNATION=n), then rcutorture complained within 10 seconds. > > Sigh!!! And Nick's patch gets rid of the rcutorture failures for me as well, now that I can reproduce them. ;-) Thanx, Paul -- To unsubscribe from this list: send the line "unsubscribe kernel-testers" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
