PROBLEM alert - Host fas03 is DOWN

Jon Masters jonathan at jonmasters.org
Sat Sep 11 07:41:32 UTC 2010


On Sat, 2010-09-11 at 02:51 -0400, Jon Masters wrote:
> On Fri, 2010-09-10 at 19:24 -0600, Stephen John Smoogen wrote:
> 
> > Sep 11 01:10:23 fas03 kernel: WARNING: at block/blk-core.c:338
> 
> > Sep 11 01:10:23 fas03 kernel: [<c044fc97>] ? warn_slowpath_common+0x77/0xb0
> > Sep 11 01:10:23 fas03 kernel: [<c05ca5dc>] ? blk_start_queue+0x6c/0x70
> > Sep 11 01:10:23 fas03 kernel: [<c044fce3>] ? warn_slowpath_null+0x13/0x20
> > Sep 11 01:10:23 fas03 kernel: [<c05ca5dc>] ? blk_start_queue+0x6c/0x70
> > Sep 11 01:10:23 fas03 kernel: [<ed63896b>] ?
> > kick_pending_request_queues+0x1b/0x30 [xen_blkfront]
> > Sep 11 01:10:23 fas03 kernel: [<ed638b80>] ?
> > blkif_interrupt+0x200/0x220 [xen_blkfront]
> > Sep 11 01:10:23 fas03 kernel: [<c04ad7c5>] ? handle_IRQ_event+0x45/0x140
> 
> The code in block/blk-core:338 contains an explicit check to ensure that
> interrupts have been disabled, but this not true since blkif_interrupt
> is not registered with IRQF_DISABLED set at the time of the setup in
> bind_evtchn_to_irqhandler. Thus it might be that interrupts are still on
> when we get to kick_pending_request_queues. Does this always happen?
> 
> This perhaps happened because upstream removed IRQF_DISABLED and now
> runs with interrupts disabled in handle_IRQ_event, so Xen won't see
> this. But on 2.6.32 this change had not yet happened. It's also 2:50am
> and I might be reading this wrong, but I at least suggest you open a
> RHEL6 bug and try a more recent kernel build.

Ah, of course I shouldn't email before bed. There's an obvious giant
spin_lock_irqsave/restore there, but as noted on xen-devel (when they
were mulling over moving all of the blkif_interrupt bits into a tasklet
jut a couple of weeks ago): "It looks like __blk_end_request_all...is
returning with interrupts enabled sometimes". I pinged some folks.

Jon.




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