PROBLEM alert - Host fas03 is DOWN

[Jon Masters]

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.

Jon.