Here are two patches from Paolo that have been crafted a couple of
months ago, but needed more validation because they were indirectly
causing instabilities in the sefltests. The root cause has been fixed in
'net' recently in commit 8c09412e584d ("selftests: mptcp: more stable
simult_flows tests").

These patches refactor the receive space and RTT estimator, overall
making DRS more correct while avoiding receive buffer drifting to
tcp_rmem[2], which in turn makes the throughput more stable and less
bursty, especially with high bandwidth and low delay environments.

Note that the first patch addresses a very old issue. 'net-next' is
targeted because the change is quite invasive and based on a recent
backlog refactor. The 'Fixes' tag is then there more as a FYI, because
backporting this patch will quickly be blocked due to large conflicts.

Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
Changes in v2:
- Patch 1: add missing READ_ONCE() and remove unused entry. (AI)
- Link to v1: https://patch.msgid.link/20260309-net-next-mptcp-reduce-rbuf-v1-0-8f471206f9c5@kernel.org

---
Paolo Abeni (2):
      mptcp: better mptcp-level RTT estimator
      mptcp: add receive queue awareness in tcp_rcv_space_adjust()

 include/trace/events/mptcp.h |  2 +-
 net/mptcp/protocol.c         | 71 +++++++++++++++++++++++++-------------------
 net/mptcp/protocol.h         | 37 ++++++++++++++++++++++-
 3 files changed, 77 insertions(+), 33 deletions(-)
---
base-commit: c149d90e260ca1b6b9175468955a15c4d95a9f3b
change-id: 20260306-net-next-mptcp-reduce-rbuf-4166ba6fb763

Best regards,
--  
Matthieu Baerts (NGI0) <matttbe@kernel.org>

Hello:

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

On Tue, 07 Apr 2026 10:45:16 +0200 you wrote:
> Here are two patches from Paolo that have been crafted a couple of
> months ago, but needed more validation because they were indirectly
> causing instabilities in the sefltests. The root cause has been fixed in
> 'net' recently in commit 8c09412e584d ("selftests: mptcp: more stable
> simult_flows tests").
> 
> These patches refactor the receive space and RTT estimator, overall
> making DRS more correct while avoiding receive buffer drifting to
> tcp_rmem[2], which in turn makes the throughput more stable and less
> bursty, especially with high bandwidth and low delay environments.
> 
> [...]

Here is the summary with links:
  - [net-next,v2,1/2] mptcp: better mptcp-level RTT estimator
    https://git.kernel.org/netdev/net-next/c/d2000361e4dd
  - [net-next,v2,2/2] mptcp: add receive queue awareness in tcp_rcv_space_adjust()
    https://git.kernel.org/netdev/net-next/c/7272d8131a9d

You are awesome, thank you!
-- 
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