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Date: Wed, 5 Aug 2026 16:58:17 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: Pavel Begunkov <asml.silence@gmail.com>
Cc: syzbot <syzbot+a78926bdac2adb52dc0e@syzkaller.appspotmail.com>,
 davem@davemloft.net, edumazet@google.com, horms@kernel.org,
 linux-kernel@vger.kernel.org, netdev@vger.kernel.org, pabeni@redhat.com,
 syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [net?] WARNING in netdev_queue_get_dma_dev
Message-ID: <20260805165817.7e1fc367@kernel.org>
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On Wed, 5 Aug 2026 09:51:10 +0100 Pavel Begunkov wrote:
> On 8/4/26 22:00, Jakub Kicinski wrote:
> > Hi Pavel, could you TAL?  
> 
> It complains on not holding rtnl, so the netdev should be not
> qops-enabled, and we acquire it with netdev_get_by_index_lock().
> It's going to be rejected later, but not sure whether netdev->lock
> protects its device and leasing logic well in this case.

Hm, I see.
 
> As a quick fix, let's fail it early in zcrx if there is no qops.

I think we can switch the lockdep check in netdev_queue_get_dma_dev()
to netdev_assert_locked(dev)?  Nothing should be calling that function
under rtnl_lock so the _compat() is a brainfart.