Re: net: hang in unregister_netdevice: waiting for lo to become free

[Daniel Borkmann]

On 01/30/2018 07:32 PM, Cong Wang wrote:
> On Tue, Jan 30, 2018 at 4:09 AM, Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote:
>> Hello,
>>
>> The following program creates a hang in unregister_netdevice.
>> cleanup_net work hangs there forever periodically printing
>> "unregister_netdevice: waiting for lo to become free. Usage count = 3"
>> and creation of any new network namespaces hangs forever.
> 
> Interestingly, this is not reproducible on net-next.

The most recent change on netns refcnt was 4ee806d51176 ("net: tcp: close
sock if net namespace is exiting") in net/net-next from 5 days ago, maybe
fixed due to that?