Hi Dan, first of all thanks for looking into this long lasting, irritating issue.
I have tried your kernel (4.13.0-30-generic #33+hf1711407v20180118b2-Ubuntu SMP) on Ubuntu 17.10 and was able to get "unregister_netdevice: waiting for lo to become free. Usage count = 1" in less than 5 minutes :-( Our environment spawns about 1 container a second that does either openvpn (both udp and tcp) or ipsec tunnel testing. I don't see any debug output in the kernel log, the lines are just old ordinary: [ 910.690908] unregister_netdevice: waiting for lo to become free. Usage count = 1 [ 920.806382] unregister_netdevice: waiting for lo to become free. Usage count = 1 [ 930.945869] unregister_netdevice: waiting for lo to become free. Usage count = 1 [ 941.025341] unregister_netdevice: waiting for lo to become free. Usage count = 1 [ 951.104797] unregister_netdevice: waiting for lo to become free. Usage count = 1 [ 961.184286] unregister_netdevice: waiting for lo to become free. Usage count = 1 [ 971.263749] unregister_netdevice: waiting for lo to become free. Usage count = 1 I don't even see any "net_free:" or "net_alloc:" messages in the log (and I checked the referrenced git and your recent patch and it does not seem to be there either). PLease let me know how to enable the debug messages, so we can finally trace it down. Thanks Jiri Horky -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1711407 Title: unregister_netdevice: waiting for lo to become free Status in linux package in Ubuntu: In Progress Status in linux source package in Trusty: In Progress Status in linux source package in Xenial: In Progress Status in linux source package in Zesty: In Progress Status in linux source package in Artful: In Progress Status in linux source package in Bionic: In Progress Bug description: This is a "continuation" of bug 1403152, as that bug has been marked "fix released" and recent reports of failure may (or may not) be a new bug. Any further reports of the problem should please be reported here instead of that bug. -- [Impact] When shutting down and starting containers the container network namespace may experience a dst reference counting leak which results in this message repeated in the logs: unregister_netdevice: waiting for lo to become free. Usage count = 1 This can cause issues when trying to create net network namespace and thus block a user from creating new containers. [Test Case] See comment 16, reproducer provided at https://github.com/fho/docker- samba-loop To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1711407/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
