On Sun, Sep 29, 2024 at 02:18:20AM -0400, Willem de Bruijn wrote:
> From: Willem de Bruijn <willemb@xxxxxxxxxx>
>
> This reverts commit 504fc6f4f7f681d2a03aa5f68aad549d90eab853.
>
> dev_queue_xmit_nit is expected to be called with BH disabled.
> __dev_queue_xmit has the following:
>
> /* Disable soft irqs for various locks below. Also
> * stops preemption for RCU.
> */
> rcu_read_lock_bh();
>
> VRF must follow this invariant. The referenced commit removed this
> protection. Which triggered a lockdep warning:
[...]
>
> Fixes: 504fc6f4f7f6 ("vrf: Remove unnecessary RCU-bh critical section")
> Link: https://lore.kernel.org/netdev/20240925185216.1990381-1-greearb@xxxxxxxxxxxxxxx/
> Reported-by: Ben Greear <greearb@xxxxxxxxxxxxxxx>
> Signed-off-by: Willem de Bruijn <willemb@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Ido Schimmel <idosch@xxxxxxxxxx>
Tested-by: Ido Schimmel <idosch@xxxxxxxxxx>
Thanks Willem!
The reason my script from 504fc6f4f7f6 did not trigger the problem is
that it was pinging the address inside the VRF, so vrf_finish_direct()
was only called from the Rx path.
If you ping the address outside of the VRF:
ping -I vrf1 -i 0.1 -c 10 -q 192.0.2.1
Then vrf_finish_direct() is called from process context and the lockdep
warning is triggered. Tested that it does not trigger after applying the
revert.
