Hello, On 03/18/2016, 09:52 PM, Tejun Heo wrote: > On Thu, Mar 17, 2016 at 01:00:13PM +0100, Jiri Slaby wrote: >>>> I have not done that yet, but today, I see: >>>> destroy_workqueue: name='req_hci0' pwq=ffff88002f590300 >>>> wq->dfl_pwq=ffff88002f591e00 pwq->refcnt=2 pwq->nr_active=0 delayed_works: >>>> pwq 12: cpus=0-1 node=0 flags=0x4 nice=-20 active=0/1 >>>> in-flight: 18568:wq_barrier_func >>> >>> So, this means that there's flush_work() racing against workqueue >>> destruction, which can't be safe. :( >> >> But I cannot trigger the WARN_ONs in the attached patch, so I am >> confused how this can happen :(. (While I am still seeing the destroy >> WARNINGs.) > > So, no operations should be in progress when destroy_workqueue() is > called. If somebody was flushing a work item, the flush call must > have returned before destroy_workqueue() was invoked, which doesn't > seem to be the case here. Can you trigger BUG_ON() or sysrq-t when > the above triggers? There must be a task which is flushing a work > item there and it shouldn't be difficult to pinpoint what's going on > from it. The output of sysrq-t is here (> 200k), but I cannot see anything suspicious in it: http://www.fi.muni.cz/~xslaby/sklad/panics/jctl.txt This is what the code does now: + if ((pwq != wq->dfl_pwq) && (pwq->refcnt > 1)) { + pr_info("%s: name='%s' pwq=%p wq->dfl_pwq=%p pwq->refcnt=%d pwq->nr_active=%d delayed_works:", + __func__, wq->name, pwq, wq->dfl_pwq, + pwq->refcnt, pwq->nr_active); + + show_pwq(pwq); + + mutex_unlock(&wq->mutex); + show_state(); + show_workqueue_state(); + WARN_ON(1); + return; + } thanks, -- js suse labs -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
