netdev - Re: IPv6 path MTU discovery broken

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Message-ID: <20130928203318.GC23654@order.stressinduktion.org>
Date:	Sat, 28 Sep 2013 22:33:18 +0200
From:	Hannes Frederic Sowa <hannes@...essinduktion.org>
To:	"Steinar H. Gunderson" <sgunderson@...foot.com>
Cc:	netdev@...r.kernel.org, edumazet@...gle.com
Subject: Re: IPv6 path MTU discovery broken

Hello!

On Fri, Sep 27, 2013 at 10:14:20PM +0200, Steinar H. Gunderson wrote:
> So the “packet too big” packets really look like they're being ignored.
> However, they _do_ reach the kernel somehow, since Icmp6InPktTooBigs
> seems to increase.
> 
> Could this be related somehow to the packets coming from 2001:67c:29f4::31,
> while the default route is to a link-local address? (An RPF issue?) This used
> to work (although it was often flaky for me) in 3.10 and before. I can't
> easily bisect, though, as I don't boot this machine too often.

This looks like a bug and should definitely get fixed. There should be
no RPF issue. May I have a look at your /proc/net/ipv6_route?

Thanks,

  Hannes

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