On Tue, 9 Nov 2021 16:12:33 +0200 Leon Romanovsky wrote:

quoted

You'd need to tell me more about what the notifier is used for (I see
RoCE in the call trace). I don't understand why you need to re-register 
a global (i.e. not per netns) notifier when devlink is switching name
spaces.  

RDMA subsystem supports two net namespace aware scenarios.

We need global netdev_notifier for shared mode. This is legacy mode where
we listen to all namespaces. We must support this mode otherwise we break
whole RDMA world.

See commit below:
de641d74fb00 ("Revert "RDMA/mlx5: Fix devlink deadlock on net namespace deletion"")

But why re-reg? To take advantage of clean event replay?

IIUC the problem is that the un-reg is called from the reload_down path.