Re: [Xen-devel] PV DomU running linux 3.17.3 causing xen-netback fatal error in Dom0

[Anthony Wright <anthony@xxxxxxxxxxxxxxx>]

On 28/11/2014 15:23, Ian Campbell wrote:
> On Fri, 2014-11-28 at 15:19 +0000, Anthony Wright wrote:
>> We have a 64 bit PV DomU that we recently upgraded from linux 3.3.2 to
>> 3.17.3
> Is this a Debian kernel? In which case you might be seeing
It's a stock kernel from kernel.org, we have a custom system with no
relation to Debian.
> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=767261 , this will be
> fixed in the next upload of the kernel, test binaries with the fixes are
> referenced in the bug log.
The error messages we're seeing are different from those reported, both
the Dom0 and DomU continue to run correctly and the vif doesn't degrade
slowly it fails the test in netback.c below which disables the interface:

    /* No crossing a page as the payload mustn't fragment. */
    if (unlikely((txreq.offset + txreq.size) > PAGE_SIZE)) {
        netdev_err(queue->vif->dev,
            "txreq.offset: %x, size: %u, end: %lu\n",
            txreq.offset, txreq.size,
            (txreq.offset&~PAGE_MASK) + txreq.size);
        xenvif_fatal_tx_err(queue->vif);
        break;
    }
> Even if not Debian then you'll probably want the same set of backports.
I'm happy to apply the backports if you think it's likely to fix the
problem despite the different symptoms, but from what I can see it looks
like a different problem.

thanks,

Anthony
> Ian.
>>  running on a 64 bit 3.17.3 Dom0 with Xen 4.4.0.
>>
>> Shortly after the upgrade we started to lose network connectivity to the
>> DomU a few times a day that required a reboot to fix. We see nothing in
>> the xen logs or xl dmesg, but when we looked at the dmesg output we saw
>> the following output for the two incidents we investigated in detail:
>>
>> [69332.026586] vif vif-4-0 vif4.0: txreq.offset: 85e, size: 4002, end: 6144
>> [69332.026607] vif vif-4-0 vif4.0: fatal error; disabling device
>> [69332.031069] br-default: port 2(vif4.0) entered disabled state
>>
>>
>> [824365.530740] vif vif-9-0 vif9.0: txreq.offset: a5e, size: 4002, end: 6656
>> [824365.530748] vif vif-9-0 vif9.0: fatal error; disabling device
>> [824365.531191] br-default: port 2(vif9.0) entered disabled state
>>
>> We have a very similar setup running on another machine with a 3.17.3
>> DomU, 3.17.3 Dom0 and Xen 4.4.0 but we can't reproduce the issue on this
>> machine. This is a test system rather than a production system so has a
>> different workload and fewer CPUs.
>>
>> The piece of code that outputs the error is in
>> drivers/net/xen-netback/netback.c.
>>
>> The DomU has 4000MB of RAM and 8 CPUs.
>>
>> Any ideas?
>>
>> Thanks,
>>
>> Anthony.
>>
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@xxxxxxxxxxxxx
>> http://lists.xen.org/xen-devel


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