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Subject: Re: AW: AW: AW: PROBLEM: Kernel Oops in UDP stack
To:     Marcel Hellwig <mhellwig@mut-group.com>,
        'Eric Dumazet' <eric.dumazet@gmail.com>,
        Paolo Abeni <pabeni@redhat.com>,
        "'davem@davemloft.net'" <davem@davemloft.net>,
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        "'yoshfuji@linux-ipv6.org'" <yoshfuji@linux-ipv6.org>,
        "'andrew@lunn.ch'" <andrew@lunn.ch>
Cc:     "'netdev@vger.kernel.org'" <netdev@vger.kernel.org>,
        "'linux-kernel@vger.kernel.org'" <linux-kernel@vger.kernel.org>,
        Matthias Wystrik <mwystrik@mut-group.com>
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From:   Eric Dumazet <eric.dumazet@gmail.com>
Message-ID: <e26dbc04-d524-d3b2-7596-1428122f2cd5@gmail.com>
Date:   Thu, 2 Aug 2018 06:05:36 -0700
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On 08/02/2018 04:02 AM, Marcel Hellwig wrote:
> Hi everyone,
> 
> I did three things that evening.
> * I created a small dts file, so I could boot a 3.5.7 kernel.
> * Ported the pskb_expand_head from 3.5.7 to 3.4.113
> * Ported the whole skbuf.{c,h} file from 3.5.7 to 3.4.113

That seems bold :0)

Sorry, we only backport one fix at a time.

You can not simply copy whole files from one version to another.

> 
> Sadly enough the second and third one panicked as well, but interestingly not the first one (3.5.7 with a simple dts file). Now the question is: Is something changed outside of the skbuf (maybe in udp.{c,h}?) or is it because the dts uses a different approach of talking to the MAC of the lpc3250?
> 
> I may try a more recent kernel with a dts file (maybe a 4.x.x one), but I think that will be impossible to backport a patch for our 2.6 kernel :(
> 
> If anybody has any more ideas about why the dts kernel does not panic, you're very welcome.
> 
> Mit freundlichen Grüßen / With kind regards
> 
> Marcel Hellwig
> B. Sc. Informatik
> Entwickler
> 
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