From: Jakub Kicinski <kuba@kernel.org>
To: Eric Dumazet <edumazet@google.com>, Ankit Garg <nktgrg@google.com>
Cc: Joshua Washington <joshwash@google.com>,
netdev@vger.kernel.org,
Harshitha Ramamurthy <hramamurthy@google.com>,
Andrew Lunn <andrew+netdev@lunn.ch>,
"David S. Miller" <davem@davemloft.net>,
Paolo Abeni <pabeni@redhat.com>,
Willem de Bruijn <willemb@google.com>,
Praveen Kaligineedi <pkaligineedi@google.com>,
Catherine Sullivan <csully@google.com>,
Luigi Rizzo <lrizzo@google.com>, Jon Olson <jonolson@google.com>,
Sagi Shahar <sagis@google.com>, Bailey Forrest <bcf@google.com>,
linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH net 0/2] gve: fix crashes on invalid TX queue indices
Date: Fri, 30 Jan 2026 16:38:25 -0800 [thread overview]
Message-ID: <20260130163825.3b63222a@kernel.org> (raw)
In-Reply-To: <CANn89iJ=Gfjves4qN6hu_VRPSedVRosJsvEQC_irFnEJU_eMLg@mail.gmail.com>
On Fri, 30 Jan 2026 21:56:07 +0100 Eric Dumazet wrote:
> Jakub, the issue is that before 4.20, calling synchronize_rcu()
> instead of synchronize_rcu_bh()
> was probably a bug. I suspect we had more issues like that.
>
> __dev_queue_xmit takes a rcu_read_lock_bh(), while the code (that you
> added in 2018 [1])
> to update the queue netif_set_real_num_tx_queues does synchronize_net()
> (aka synchronize_rcu()) and in earlier times, it would mean that this
> would maybe return too soon (say on preemptible kernels)
>
> [...]
>
> So perhaps a fix for pre 4.20 kernel would be: (I kept the
> synchronize_net() to be really cautious and because I really do not
> want to test)
Sounds entirely plausible, FWIW. Ankit, this would mean that you have
to convince RHEL / Rocky to take Eric's patch. Oldest kernel we can
patch upstream is 5.10, AFAIK.
prev parent reply other threads:[~2026-01-31 0:38 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-05 23:25 [PATCH net 0/2] gve: fix crashes on invalid TX queue indices Joshua Washington
2026-01-05 23:25 ` [PATCH net 1/2] gve: drop packets on invalid queue indices in GQI TX path Joshua Washington
2026-01-05 23:25 ` [PATCH net 2/2] gve: drop packets on invalid queue indices in DQO " Joshua Washington
2026-01-07 2:22 ` [PATCH net 0/2] gve: fix crashes on invalid TX queue indices Jakub Kicinski
2026-01-08 15:35 ` Ankit Garg
2026-01-08 16:31 ` Jakub Kicinski
2026-01-08 16:37 ` Eric Dumazet
2026-01-08 20:53 ` Ankit Garg
2026-01-30 20:56 ` Eric Dumazet
2026-01-31 0:38 ` Jakub Kicinski [this message]
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