Re: regression ioatdma 3.3

[Jonathan Nieder <jrnieder@gmail.com>]

forwarded 660554 http://thread.gmane.org/gmane.comp.emulators.xen.devel/121604
quit
(cc-ing Thomas, since he ran into the same bug)
Hi,

Konrad Rzeszutek Wilk wrote:
> On Fri, Jan 27, 2012 at 02:31:55PM +0100, William Dauchy wrote:

>> I have some troubles loading the IOATDMA module under xen4.1.2 and a
>> linux dom0 3.3
>
> So you are using the rc1 version? What exact git commit are you using?

Broken:

 v3.2.6 + Debian patches (zigo)
 v3.3-rc2~22 (William)

Not broken:

 v3.1.8 + Debian patches, presumably (zigo)
 v3.1.5 (William)

[...]
>> Here is the call trace when loading the module in dom0:
>
> Is the problem present with baremetal (same exact kernel?)

No.

> Do you see this if you run a 64-bit dom0?

I'm guessing not, just based on the crazy coincidence that both
reports were with 32-bit kernels.  But who knows. ;-)

[...]
>> kernel BUG at /linux-3.3/drivers/dma/ioat/dma_v2.c:163!
>> invalid opcode: 0000 [#1] SMP
>> Modules linked in: ioatdma(+) dca ebt_ip6 ebt_dnat ebt_ip
>> ebtable_broute ebt_snat ebtable_nat ebtable_filter ebtables bridge stp
>> llc ipv6 iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi scsi_mod
>> button
>> 
>> Pid: 0, comm: swapper/0 Not tainted 3.3.0-dom0-6357-i386+ #24 Dell   C6100           /0D61XP

This is

	active = ioat2_ring_active(ioat);
	for (i = 0; i < active && !seen_current; i++) {
		...
		if (tx->phys == phys_complete)
			seen_current = true;
	}
	...
	BUG_ON(active && !seen_current); /* no active descs have written a completion? */

Any hints for tracking it down?

Thanks,
Jonathan