netdev - Re: 4.4.1 skb_warn_bad

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Date:	Tue, 23 Feb 2016 20:01:38 -0500
From:	Wakko Warner <wakko@...mx.eu.org>
To:	Hannes Frederic Sowa <hannes@...essinduktion.org>
Cc:	linux-kernel@...r.kernel.org,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: 4.4.1 skb_warn_bad_offload+0xc5/0x110

Please keep me in CC.

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.

-- 
 Microsoft has beaten Volkswagen's world record.  Volkswagen only created 22
 million bugs.