Re: [PATCH net v2 1/2] net: advertise TCP MSS from the configured MTU, not the learned PMTU

From: patchwork-bot+netdevbpf

Date: Thu Aug 20 2026 - 15:35:13 EST


Hello:

This series was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@xxxxxxxxxx>:

On Sat, 15 Aug 2026 15:03:36 +0800 you wrote:
> The MSS a host puts in its SYN tells the peer how big a segment it may
> send us. Right now we can shrink it with a PMTU we learned on our own
> send path, which is the wrong direction entirely.
>
> On asymmetric paths this bites - think DSR load balancers, where the
> request side goes through a smaller-MTU overlay. We learn a small PMTU
> going out, then advertise a small MSS, and the peer stays capped for the
> whole connection even though its path back to us is wide. MSS only shows
> up in the SYN and never grows back.
>
> [...]

Here is the summary with links:
- [net,v2,1/2] net: advertise TCP MSS from the configured MTU, not the learned PMTU
https://git.kernel.org/netdev/net/c/2640e6419594
- [net,v2,2/2] selftests: net: packetdrill: add tests for advertised MSS with PMTU exceptions
https://git.kernel.org/netdev/net/c/e5c8e301b497

You are awesome, thank you!
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