netem is broken in 6.18

---------- Forwarded message ---------
From: <[email protected]>
Date: Fri, Nov 21, 2025 at 3:39 PM
Subject: [Bug 220774] netem is broken in 6.18
To: <[email protected]>

https://bugzilla.kernel.org/show_bug.cgi?id=220774

Gerlinde ([email protected]) changed:

What |Removed |Added
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CC| |[email protected]

--- Comment #2 from Gerlinde ([email protected]) ---
You know, in our HA and ECMP setup we sometimes get this strange thing: packets are not lost, but some flows get duplicated for a few hundert milliseconds. Not all flows, only the unlucky ones that get hashed through the broken path. And this makes debugging really a pain, because all metrics say “no loss”, but the application still behave stupid.

So we use netem duplicate on a single mq-queue to copy exactly this situation.

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Hi [email protected] (sorry, no name on that email!),

I may be misunderstanding: You seem to be using a single mq-queue with netem and your requirement seems to be replicating the packet on that single mq-queue? You mention "flow" - how do you map these to the queues?
BTW, you may be aware of this, but you should also be able to mirror arbitrary flows of choice without resorting to using netem. Can you share your config?

cheers,
jamal