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SubjectRe: 4.4.1 skb_warn_bad_offload+0xc5/0x110
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On 24.02.2016 02:46, Wakko Warner wrote:
> Please keep me in CC.
>
> Wakko Warner wrote:
>>
>> Hannes Frederic Sowa wrote:
>>> [full-quote for netdev]
>>>
>>> Hello,
>>>
>>> On 16.02.2016 01:08, Wakko Warner wrote:
>>>> I've been seeing the following on some of my VMs ran under qemu. The VMs do
>>>> not have internet connectivity. This happened when some files were accessed
>>>> via NFS to another VM (NOTE: Both VMs throw these warnings. Both VMs are
>>>> running the exact same kernel). The host is also throwing these warnings
>>>> and is also 4.4.1, but not the same kernel build.
>>>>
>>>> The issue appears to have gone away if I issue the following on the guests
>>>> and on the host (except br0 instead of eth0 on host)
>>>> ethtool -K eth0 gso off gro off ufo off tso off
>>>>
>>>> On the host, br0 does not have any interfaces enslaved except for the
>>>> interface for the VMs and also does not have an IPv4 address assigned.
>>>>
>>
>>> Can you try the following patch?
>>>
>>> --- a/net/ipv4/ip_output.c
>>> +++ b/net/ipv4/ip_output.c
>>> @@ -1233,6 +1233,9 @@ ssize_t ip_append_page(struct sock *sk,
>>> struct flowi4 *fl4, struct page *page,
>>> if (!skb)
>>> return -EINVAL;
>>>
>>> + if (skb->ip_summed != CHECKSUM_PARTIAL)
>>> + return -EINVAL;
>>> +
>>> cork->length += size;
>>> if ((size + skb->len > mtu) &&
>>> (sk->sk_protocol == IPPROTO_UDP) &&
>>
>> Still received the warning. I saw it on the host and on one of the VMs.
>> The VM in this case was an nfs server. The client did not receive the
>> warning. I should mention that I'm using v3 and udp on the client for the
>> mount options.
>>
>> I'm not sure if this change effected nfsd on one of the VMs, it isn't working
>> at all on it.
>
> I reverted back to the previous kernel for the VM only and the nfsd on the
> one VM started working.
>
> I should note that when I added this change, I only compiled the kernel and
> copied the bzImage file. I did not recompile any modules nor copy the
> system.map over.

Actually, I could reproduce it locally thus I pushed a slightly
different patch already. You have to patch all VMs in terms to not get
the warning in the hypervisor anymore.

Bye,
Hannes

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