On Monday 09 November 2009, Thomas Gleixner wrote: > On Mon, 9 Nov 2009, Ingo Molnar wrote: > > > > * Rafael J. Wysocki <rjw@xxxxxxx> wrote: > > > > > On Monday 09 November 2009, Ingo Molnar wrote: > > > > > > > > * Rafael J. Wysocki <rjw@xxxxxxx> wrote: > > > > > > > > > [ 2016.865041] BUG: using smp_processor_id() in preemptible [00000000] code: events/1/29920 > > > > > [ 2016.865344] caller is vmstat_update+0x13/0x48 > > > > > [ 2016.865522] Pid: 29920, comm: events/1 Not tainted 2.6.31-tst #158 > > > > > [ 2016.865700] Call Trace: > > > > > [ 2016.865877] [<ffffffff811608e8>] debug_smp_processor_id+0xc4/0xd4 > > > > > [ 2016.866052] [<ffffffff810a9ae1>] vmstat_update+0x13/0x48 > > > > > [ 2016.866232] [<ffffffff81051ee6>] worker_thread+0x18b/0x22a > > > > > [ 2016.866409] [<ffffffff810a9ace>] ? vmstat_update+0x0/0x48 > > > > > [ 2016.866578] [<ffffffff810556a5>] ? autoremove_wake_function+0x0/0x38 > > > > > [ 2016.866749] [<ffffffff81288803>] ? _spin_unlock_irqrestore+0x35/0x37 > > > > > [ 2016.866935] [<ffffffff81051d5b>] ? worker_thread+0x0/0x22a > > > > > [ 2016.867113] [<ffffffff8105547d>] kthread+0x69/0x71 > > > > > [ 2016.867278] [<ffffffff8100c1aa>] child_rip+0xa/0x20 > > > > > [ 2016.867450] [<ffffffff81055414>] ? kthread+0x0/0x71 > > > > > [ 2016.867618] [<ffffffff8100c1a0>] ? child_rip+0x0/0x20 > > > > > > > > a bug producing similar looking messages was fixed by: > > > > > > > > fd21073: sched: Fix affinity logic in select_task_rq_fair() > > > > > > > > but that bug was introduced by: > > > > > > > > a1f84a3: sched: Check for an idle shared cache in select_task_rq_fair() > > > > > > I guess these are tip commits? > > > > yep, tip:sched/core ones. > > > > > > Which is for v2.6.33, not v2.6.32. > > > > > > The one I saw was in the Linus' tree, quite obviously. > > > > ok, then my observation should not apply. > > I think it _IS_ releated because the worker_thread is CPU affine and > the debug_smp_processor_id() check does: > > if (cpumask_equal(¤t->cpus_allowed, cpumask_of(this_cpu))) > > which prevents that usage of smp_processor_id() in ksoftirqd and > keventd in preempt enabled regions is warned on. > > We saw exaclty the same back trace with fd21073 (sched: Fix affinity > logic in select_task_rq_fair()). > > Rafael, can you please add a printk to debug_smp_processor_id() so we > can see on which CPU we are running ? I suspect we are on the wrong > one. Well, I can add the printk(), but I can't guarantee that I will get the call trace once again. So far I've seen it only once after 20-25 consecutive suspend-resume cycles, so ... you get the idea. However, running on a wrong CPU would very nicely explain all of the observed symptoms, so I guess we can try a House M.D.-alike approach and assume that the answer is "yes, we're running on the wrong CPU". What would we do next if that was the case? Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
