Re: [Xen-devel] irq problem with 3.3-rc3 on guest

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Sun, 2012-02-12 at 21:33 +0000, M A Young wrote:
> I get the backtrace below if I try to boot a PV guest running F17 Alpha 
> TC2 in graphical mode. Is this a known problem?

It came up last year https://lkml.org/lkml/2011/1/6/19 which resulted in
the WARN_ON you saw instead of a kernel crash. I'm not sure if anyone
got to the bottom of the root cause though.

That occasion was a suspend/resume thing so perhaps not really related
but it seems fishily similar.

I've not looked at the code recently but it seems that back then I was
of the opinion that info->update_wanted == 0 must remain true until the
irq etc was all fully setup, that might be relevant now?

Ian.

> 
>       Michael Young
> 
> WARNING: at drivers/xen/events.c:209 evtchn_from_irq+0x41/0x50()
> Invalid irq -1!
> Modules linked in:
> Pid: 17, comm: xenbus Tainted: G        W 
> 3.3.0-0.rc3.git3.1.fc17.x86_64 #1
> Call Trace:
>   <IRQ>  [<ffffffff8106047f>] warn_slowpath_common+0x7f/0xc0
>   [<ffffffff81060576>] warn_slowpath_fmt+0x46/0x50
>   [<ffffffff8100f942>] ? check_events+0x12/0x20
>   [<ffffffff813c5bf1>] evtchn_from_irq+0x41/0x50
>   [<ffffffff813c6302>] notify_remote_via_irq+0x12/0x50
>   [<ffffffff8137e016>] xenfb_event_handler+0x26/0x50
>   [<ffffffff8110b0fc>] handle_irq_event_percpu+0x6c/0x390
>   [<ffffffff8110b468>] handle_irq_event+0x48/0x70
>   [<ffffffff8110e7b7>] handle_edge_irq+0x77/0x110
>   [<ffffffff813c56f3>] __xen_evtchn_do_upcall+0x1c3/0x290
>   [<ffffffff813c782f>] xen_evtchn_do_upcall+0x2f/0x50
>   [<ffffffff816a7a3e>] xen_do_hypervisor_callback+0x1e/0x30
>   <EOI>  [<ffffffff8100140a>] ? hypercall_page+0x40a/0x1000
>   [<ffffffff8100140a>] ? hypercall_page+0x40a/0x1000
>   [<ffffffff813c9ed7>] ? xb_read+0xd7/0x190
>   [<ffffffff811a2359>] ? kmem_cache_alloc_trace+0xd9/0x240
>   [<ffffffff813cb170>] ? unregister_xenbus_watch+0x1d0/0x1d0
>   [<ffffffff813cb1f9>] ? xenbus_thread+0x89/0x2b0
>   [<ffffffff81089ac7>] ? kthread+0xb7/0xc0
>   [<ffffffff810cd02d>] ? trace_hardirqs_on+0xd/0x10
>   [<ffffffff816a78f4>] ? kernel_thread_helper+0x4/0x10
>   [<ffffffff8169dcb4>] ? retint_restore_args+0x13/0x13
>   [<ffffffff816a78f0>] ? gs_change+0x13/0x13
> 
> 
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