Re: [PATCH net v3] net: openvswitch: fix race on port output

Eric Dumazet
2023-04-07T08:48:53Z

On Wed, Apr 5, 2023 at 9:53 AM Felix Huettner
<felix.huettner@mail.schwarz> wrote:
>
> assume the following setup on a single machine:
> 1. An openvswitch instance with one bridge and default flows
> 2. two network namespaces "server" and "client"
> 3. two ovs interfaces "server" and "client" on the bridge
> 4. for each ovs interface a veth pair with a matching name and 32 rx and
> tx queues
> 5. move the ends of the veth pairs to the respective network namespaces
> 6. assign ip addresses to each of the veth ends in the namespaces (needs
> to be the same subnet)
> 7. start some http server on the server network namespace
> 8. test if a client in the client namespace can reach the http server
>
> when following the actions below the host has a chance of getting a cpu
> stuck in a infinite loop:
> 1. send a large amount of parallel requests to the http server (around
> 3000 curls should work)
> 2. in parallel delete the network namespace (do not delete interfaces or
> stop the server, just kill the namespace)
>
> there is a low chance that this will cause the below kernel cpu stuck
> message. If this does not happen just retry.
> Below there is also the output of bpftrace for the functions mentioned
> in the output.
>
...
Reviewed-by: Eric Dumazet <edumazet@google.com>