On Mon, 14 Aug 2023 11:35:26 +0200 Sebastian Andrzej Siewior wrote:

The RPS code and "deferred skb free" both send IPI/ function call
to a remote CPU in which a softirq is raised. This leads to a warning on
PREEMPT_RT because raising softiqrs from function call led to undesired
behaviour in the past. I had duct tape in RT for the "deferred skb free"
and Wander Lairson Costa reported the RPS case.

Could you find a less invasive solution?
backlog is used by veth == most containerized environments.
This change has a very high risk of regression for a lot of people.