netdev - Re: Regression for ip6-in-ip4 IPsec tunnel in 4.14.16

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Date:   Thu, 08 Feb 2018 13:40:24 +0100
From:   Yves-Alexis Perez <corsac@...ian.org>
To:     Mike Maloney <maloneykernel@...il.com>
Cc:     Mike Maloney <maloney@...gle.com>,
        "David S. Miller" <davem@...emloft.net>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        netdev <netdev@...r.kernel.org>, linux-kernel@...r.kernel.org,
        Eric Dumazet <edumazet@...gle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, debian-kernel@...ts.debian.org,
        Tobias Brunner <tobias@...ongswan.org>
Subject: Re: Regression for ip6-in-ip4 IPsec tunnel in 4.14.16

On Wed, 2018-02-07 at 20:46 +0100, Yves-Alexis Perez wrote:
> Maybe. I tried with removing the MTU setting, and I get (on ping again)
> 
> févr. 07 20:44:01 scapa kernel: mtu: 1266
> 
> which means I would get -EINVAL on standards kernels, which is not really good
> either.

Actually after rebooting on the Debian 4.14.17 kernel, with the outter MTU
unset (or set to 1360), I don't get the -EINVAL anymore, so maybe it'd be OK.

Unfortunately I have the feeling that debugging this will be a bit tricky for
other people. MTU tuning for tunnels are always a bit confusing, but having
the kernel return EINVAL on a ping doesn't really help narrowing it down to
that MTU setting. Not sure if some kind of logging could be added to help?

Regards,
-- 
Yves-Alexis
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