Subject: Re: [PATCH] net/ipv4/ip_gre.c net/ipv6/ip6_gre.c: ip and gre header are recorded twice

From: Jakub Kicinski <[email-masked]>
Date: Fri, 1 Jul 2022 18:42:22 -0700

On Fri, 1 Jul 2022 18:31:51 -0700 Jakub Kicinski wrote:
> On Tue, 28 Jun 2022 18:18:27 +0300 Aleksey Shumnik wrote:
> > pre-up ip tunnel add mgre0 mode ip6gre local 4444::1111 key 1 ttl 64 tos inherit  
> 
> I can't get GRE6 tunnels to work as NBMA net at all.
> AFAICT ip6gre_tunnel_xmit() takes the endpoint addresses straight 
> from the netdev, only ip6tnl seems to be doing a lookup.
> Am I doing it wrong?

If it's just v4 could perhaps be commit fdafed459998 ("ip_gre: set
dev->hard_header_len and dev->needed_headroom properly"). Would you 
be able to try some kernel older than 5.8?