simpler reproducer for this using LXD instead of Docker: 1. install/setup LXD $ sudo apt install lxd $ sudo lxd init
2. create two containers $ lxc launch ubuntu:xenial server $ lxc launch ubuntu:xenial client 3. make the client privileged (so it can mount smb/cifs) $ lxc config set client security.privileged true $ lxc stop client $ lxc start client 4. set up samba server in container $ lxc exec server apt update $ lxc exec server apt install cifs-utils samba $ lxc exec server mkdir /dummy $ lxc exec server touch /dummy/emptyfile $ lxc exec server vim /etc/samba/smb.conf add this section at the end of the container's smb.conf: [dummy] path = /dummy browseable = yes read only = yes guest ok = yes $ lxc stop server $ lxc start server 5. note server container's ip $ lxc list server e.g. | server | RUNNING | 10.109.201.68 (eth0) 6. setup client container $ lxc exec client mkdir /dummy $ lxc exec apt update $ lxc exec apt install cifs-utils 7. stop client container $ lxc stop client 8. full cycle of client container start through stop $ lxc start client ; sleep 2 ; lxc exec client -- mount -o guest //10.109.201.68/dummy /dummy ; lxc exec client -- ls -l /dummy ; lxc exec client umount /dummy ; lxc stop -f client 9. repeat client cycle; it should hang due to this bug $ lxc start client ; sleep 2 ; lxc exec client -- mount -o guest //10.109.201.68/dummy /dummy ; lxc exec client -- ls -l /dummy ; lxc exec client umount /dummy ; lxc stop -f client Note this force-stops the container, instead of normally stopping it; if the container is allowed to exit normally, the problem isn't reproduced (with these steps, at least). Also note the 'sleep 2' is there to give enough time for the client container network to come up, it may need to be increased if your client container takes longer to assign its ip address (you can edit the client container nw config to use a static address if you want, which should be faster). -- 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
