On Wed, Jul 27, 2016 at 05:23:05PM +0200, Thomas Gleixner wrote: > On Wed, 27 Jul 2016, Heiko Carstens wrote: > > [ 3.162961] ([<0000000000176c30>] select_task_rq+0xc0/0x1a8) > > [ 3.162963] ([<0000000000177d64>] try_to_wake_up+0x2e4/0x478) > > [ 3.162968] ([<000000000015d46c>] create_worker+0x174/0x1c0) > > [ 3.162971] ([<0000000000161a98>] alloc_unbound_pwq+0x360/0x438) > > > For some unknown reason select_task_rq() gets called with a task that has > > nr_cpus_allowed == 0. Hence "cpu = cpumask_any(tsk_cpus_allowed(p));" > > within select_task_rq() will set cpu to nr_cpu_ids which in turn causes the > > warning later on. > > > > It only happens with more than one node, otherwise it seems to work fine. > > > > Any idea what could be wrong here? > > create_worker() > tsk = kthread_create_on_node(); > kthread_bind_mask(tsk, pool->attrs->cpumask); > do_set_cpus_allowed(tsk, mask); > set_cpus_allowed_common(tsk, mask); > cpumask_copy(&tsk->cpus_allowed, mask); > tsk->nr_cpus_allowed = cpumask_weight(mask); > wake_up_process(task); > > So this looks like pool->attrs->cpumask is simply empty.....
Just had some time to look into this a bit more. Looks like we initialize the cpu_to_node_masks (way) too late on s390 for fake numa. So Peter's patch just revealed that problem. I'll see if initializing the masks earlier will fix this, but I think it will.
