Bug#1108860: linux-image-6.1.0-34-amd64: Wireguard fragmentation fails with VXLAN since kernel 6.1.0-34, causing network timeouts
control: tags -1 + moreinfo
Hi Charles,
On Sun, Jul 06, 2025 at 08:59:46PM +0200, Salvatore Bonaccorso wrote:
> Hi Charles,
>
> On Sun, Jul 06, 2025 at 07:43:35PM +0200, rough.rock3059@datachamp.fr wrote:
> > Hi,
> >
> > Thank you for the quick reply.
> >
> > We tried kernel versions 6.12.35-1 from unstable and 6.15.4-1 from
> > experimental and the issue still appears on both versions.
>
> Ack, thanks for confirming that, I just updated the bug metadata to
> reflect that.
>
> > We are currently bisecting the changes to identify the commit. This
> > will take several days as the server is used in production and we
> > need to minimize downtime during working hours. I will get back to
> > this issue as soon as the commit is identified.
>
> Yes that is fully understandable. Would be ideal if that can be
> reproduced under lab conditions, but then this takes just the time it
> needs.
>
> Ping us back once you have identified the breaking commit.
>
> Thanks for your debugging.
I'm not sure where you are right now at the bisect. But yesterday in
our weekly kernel-team meeting we talked about your issue. And Ben
pointed out that he saw recently a PMTU related change.
And in fact htere is 8930424777e4 ("tunnels: Accept PACKET_HOST in
skb_tunnel_check_pmtu().") which is from 6.15-rc1. And it got
backported to various stable series, for your report of interest is
that it was backported to 6.1.134, which falls exactly in the range
you noticed of breaking.
Thus: are you able to test first at all 6.1.y and a revert of the
given commit on top and see if that fixes your issue?
Regards,
Salvatore
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