On 12/15/25 1:31 PM, Eelco Chaudron wrote:
> On 15 Dec 2025, at 12:58, Toke Høiland-Jørgensen wrote:
>> Eelco Chaudron <[email protected]> writes:
>>> On 11 Dec 2025, at 12:50, Toke Høiland-Jørgensen wrote:
>>>> The openvswitch teardown code will immediately call
>>>> ovs_netdev_detach_dev() in response to a NETDEV_UNREGISTER notification.
>>>> It will then start the dp_notify_work workqueue, which will later end up
>>>> calling the vport destroy() callback. This callback takes the RTNL to do
>>>> another ovs_netdev_detach_port(), which in this case is unnecessary.
>>>> This causes extra pressure on the RTNL, in some cases leading to
>>>> "unregister_netdevice: waiting for XX to become free" warnings on
>>>> teardown.
>>>>
>>>> We can straight-forwardly avoid the extra RTNL lock acquisition by
>>>> checking the device flags before taking the lock, and skip the locking
>>>> altogether if the IFF_OVS_DATAPATH flag has already been unset.
>>>>
>>>> Fixes: b07c26511e94 ("openvswitch: fix vport-netdev unregister")
>>>> Tested-by: Adrian Moreno <[email protected]>
>>>> Signed-off-by: Toke Høiland-Jørgensen <[email protected]>
>>>
>>> Guess the change looks good, but I’m waiting for some feedback from
>>> Adrian to see if this change makes sense.
>>
>> OK.
>>
>>> Any luck reproducing the issue it’s supposed to fix?
>>
>> We got a report from the customer that originally reported it (who had
>> their own reproducer) that this patch fixes their issue to the point
>> where they can now delete ~2000 pods/node without triggering the
>> unregister_netdevice warning at all (where before it triggered at around
>> ~500 pod deletions). So that's encouraging :)
> 
> That’s good news; just wanted to make sure we are not chasing a red herring :)
> 
> Acked-by: Eelco Chaudron [email protected]

@Eelco: your SoB above is lacking the required <> around the email
address. I'm fixing that while applying the patch, but please take care
of it in the next reviews.

Thanks,

Paolo

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