linux-kernel - Re: [PATCH net-next] net: veth: Disable netpoll support

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20251204173421.23841106@kernel.org>
Date: Thu, 4 Dec 2025 17:34:21 -0800
From: Jakub Kicinski <kuba@...nel.org>
To: Fabian Grünbichler <f.gruenbichler@...xmox.com>
Cc: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
 <edumazet@...gle.com>, Breno Leitao <leitao@...ian.org>, Paolo Abeni
 <pabeni@...hat.com>, leit@...a.com, open list
 <linux-kernel@...r.kernel.org>, "open list:NETWORKING DRIVERS"
 <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next] net: veth: Disable netpoll support

On Thu, 04 Dec 2025 10:20:06 +0100 Fabian Grünbichler wrote:
> On August 5, 2024 11:40 am, Breno Leitao wrote:
> > The current implementation of netpoll in veth devices leads to
> > suboptimal behavior, as it triggers warnings due to the invocation of
> > __netif_rx() within a softirq context. This is not compliant with
> > expected practices, as __netif_rx() has the following statement:
> > 
> > 	lockdep_assert_once(hardirq_count() | softirq_count());
> > 
> > Given that veth devices typically do not benefit from the
> > functionalities provided by netpoll, Disable netpoll for veth
> > interfaces.  
> 
> this patch seems to have broken combining netconsole and bridges with
> veth ports:
> 
> https://bugzilla.proxmox.com/show_bug.cgi?id=6873
> 
> any chance this is solvable?

What's the reason to set up netcons over veth?
Note that unlike normal IP traffic netcons just blindly pipes out fully
baked skbs, it doesn't use the IP stack. So unlike normal IP traffic
I think you can still point it at the physical netdev, even if that
physical netdev is under a bridge.