linux-kernel - Re: netconsole: HARDIRQ-safe -> HARDIRQ-unsafe lock order warning

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Message-ID: <20250814172326.18cf2d72@kernel.org>
Date: Thu, 14 Aug 2025 17:23:26 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Breno Leitao <leitao@...ian.org>
Cc: Mike Galbraith <efault@....de>, paulmck@...nel.org,
 asml.silence@...il.com, LKML <linux-kernel@...r.kernel.org>,
 netdev@...r.kernel.org, boqun.feng@...il.com
Subject: Re: netconsole:  HARDIRQ-safe -> HARDIRQ-unsafe lock order warning

On Thu, 14 Aug 2025 03:16:11 -0700 Breno Leitao wrote:
>  2.2) netpoll 				// net poll will call the network subsystem to send the packet
>  2.3) lock(&fq->lock);			// Try to get the lock while the lock was already held

Where does netpoll take fq->lock ?

We started hitting this a lot in the CI as well, lockdep must have
gotten more sensitive in 6.17. Last I checked lockdep didn't understand
that we manually test for nesting with netif_local_xmit_active().