his information might be relevant. We are able to reproduce the problem with unregister_netdevice: waiting for lo to become free. Usage count = 1 with 4.14.0-rc3 kernel with CONFIG_PREEMPT_NONE=y and running only on one CPU with following boot kernel options:
BOOT_IMAGE=/boot/vmlinuz-4.14.0-rc3 root=/dev/mapper/vg0-root ro quiet vsyscall=emulate nosmp Once we hit this state, it stays in this state and reboot is needed. No more containers can be spawned. We reproduce it by running images doing ipsec/openvpn connections + downloading a small file inside the tunnels. Then the instances exist (usually they run < 10s). We run 10s of such containers a minute on one machine. With the abovementioned settings (only 1cpu), the machine hits it in ~2 hours. Another reproducer with the same kernel, but without limiting number of CPUs, is to jus run iperf in UDP mode for 3 seconds inside the container (so there is no TCP communication at all). If we run 10 of such containers in parallel, wait for all of them to finish and do it again, we hit the trouble in less than 10 minutes (on 40 cores machine). In both of our reproducers, we added "ip route flush table all; ifconfig down; sleep 10" before existing from containers. It does not seem to have any effect. -- 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
