Re: [PATCH net] netpoll: run NAPI poll in softirq context to avoid rq->lock self-deadlock

[Jakub Kicinski]

On Tue, 16 Jun 2026 19:02:57 +0200 Peter Zijlstra wrote:
> > So this is not an issue since commit 7eab73b18630e ("netconsole: convert
> > to NBCON console infrastructure"). Because from here now on writes are
> > deferred to the nbcon thread. So this purely about -stable in this case.  
> 
> Hmm, I thought netconsole had some reserved skbs and could to writes
> 'atomic' like? That said, it was 2.6 era the last time I looked at
> netconsole.

Yes, that part is fine. The problem is that netconsole tries
to reap Tx completions if the Tx queue is full. We can't call
skb destructor in irq context so we put the completed skbs on
a queue and try to arm softirq to get to them later.
Arming softirq causes a ksoftirq wake up.

We already skip the completion polling if we detect getting called
from the same networking driver. It's best effort, anyway.
Networking-side fix would be to toss another OR condition into
the skip. But we don't have one that'd work cleanly :S