Subject: Re: [Bugme-new] [Bug 16529] New: xennet driver crashes when using with pseudowire aka l2tpv3

From: Andrew Morton <[email-masked]>
Date: Wed, 25 Aug 2010 15:31:07 -0700

(switched to email.  Please respond via emailed reply-to-all, not via the
bugzilla web interface).

On Fri, 6 Aug 2010 12:46:18 GMT
[email-masked] wrote:

> https://bugzilla.kernel.org/show_bug.cgi?id=16529
> 
>            Summary: xennet driver crashes when using with pseudowire aka
>                     l2tpv3
>            Product: Networking
>            Version: 2.5
>     Kernel Version: 2.6.35
>           Platform: All
>         OS/Version: Linux
>               Tree: Mainline
>             Status: NEW
>           Severity: normal
>           Priority: P1
>          Component: Other
>         AssignedTo: [email-masked]
>         ReportedBy: [email-masked]
>         Regression: No
> 
> 
> I tried to use use the new l2tpv3 implementation on two xen domU's but one of
> them is crashing when the first l2tpv3 packet is received.
> 
> As a great man mentioned: 
> --
> guessing that eth_type_trans() has tried to pull an ethernet header from
> the skb and has run off the end, which suggests an issue with the skb
> that was passed up. Does the ethernet driver do proper alignment of data
> in its skbs? Perhaps it doesn't allocate as much headroom as other
> drivers? Perhaps the L2TP code assumes things about the skb that aren't
> valid..
> --
> Here is a link for the setup
> http://www.pastebin.org/445975
> and here a link with more details about the crash http://pastebin.org/449221
> 
> According the the hints from James Chapmann we tried generic x86 with a
> different nic driver like e1000 and this works without any problem. 
> 
> Iam using OpenWrt to create the system images. To speed up the process i would
> prepare Xen images, make them available or whatever is wished because
> pseudowire is already ready in OpenWrt Trunk so that every man also with "price
> sensitivy" hardware can use it.
> 

Seems to be a problem with xennet afacit?