Messages in this thread | | | Date | Tue, 19 Jul 2011 15:17:03 -0700 | Subject | Re: BUG spinlock lockup, rtc related, 3.0-rc7+ | From | john stultz <> |
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On Wed, Jul 13, 2011 at 10:29 AM, Ben Greear <greearb@candelatech.com> wrote: > This is on the same nfs testing machine I've been posting about. This > has some additional nfs patches included, running tests to mount, do io, > unmount > over and over again. Seems that the NFS bugs might be finally fixed, but > system is still un-stable in general when under load. > > This info was printed after several other warnings that I previously posted > to lkml. > > This one appears to lock up the machine pretty badly though...can't ssh into > it anymore, and similar messages keep spewing every few minutes. > > I *think* the BUG at the end of this email is the important part, but > maybe it's just a symptom of something else...
Huh. So does this trigger frequently, or was this just a one time thing? I suspect the latter.
From the looks of it, there's the btserver process (on cpu4) which during exit is caught up spinning trying to get the hrtimer base lock from hrtimer_cancel() in rtc_irq_set_state() when cleaning up from rtc_device_release().
Meanwhile, On cpu0, a rtc periodic timer has fired and we're stuck in rtc_handle_legacy_irq(), likely waiting for the irq_task_lock held by cpu4 in rtc_irq_set_state().
The rest of the cpus are idle, with the exception of the one that detected the stall from the normal timer tick.
Hrmm.. It sounds like a circular lock between the rtc->irq_task_lock and the hrtimer base lock.
rtc_irq_set_state: Grab irq_task_lock -> call hrtimer_cancel -> grab hrtimer_base_lock
IRQ: grab hrtimer_base_lock -> run timers -> rtc_handle_legacy_irq -> grab irq_task_lock
But looking at __run_hrtimer(), the base lock should be released before the timer is run.
So I'm not really sure what would be gumming up things here.
Thomas: Any thoughts? There shouldn't be an issue calling hrtimer_cancel or other hrtimer operations from an hrtimer handler right?
thanks -john -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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