Just chiming in here, I contacted Rodrigo off-list and was verging towards that same patch. More below.
I suspect there's two issues here with very similar symptoms. In particular post #8 which mentions people reporting that 3.14 improves the situation. https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1403152/comments/8 I've been chasing a bug in 3.13 with docker containers and connection tracking which is fixed in 3.14, by this patch: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=e53376bef2cd97d3e3f61fdc677fb8da7d03d0da Note that the commit message for the above commit fixes a different issue, but I've been able to produce issues of the nature in this thread (hung docker / ip netns add commands like in post #6) before applying this patch, but cannot reproduce after. https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1403152/comments/6 In the issue that I face, I can find a kworker thread using up an entire core, and when I cat /proc/$pid/stack I see this: <ffffffffbe01e9b6>] ___preempt_schedule+0x56/0xb0 [<ffffffffc02223e4>] nf_ct_iterate_cleanup+0x134/0x160 [nf_conntrack] [<ffffffffc0223dae>] nf_conntrack_cleanup_net_list+0x4e/0x170 [nf_conntrack] [<ffffffffc022436d>] nf_conntrack_pernet_exit+0x4d/0x60 [nf_conntrack] [<ffffffffbe6040d3>] ops_exit_list.isra.1+0x53/0x60 [<ffffffffbe6048d0>] cleanup_net+0x100/0x1d0 [<ffffffffbe084991>] process_one_work+0x171/0x470 [<ffffffffbe08563b>] worker_thread+0x11b/0x3a0 [<ffffffffbe08bb82>] kthread+0xd2/0xf0 [<ffffffffbe71757c>] ret_from_fork+0x7c/0xb0 [<ffffffffffffffff>] 0xffffffffffffffff The kworker is looping forever and failing to clean up conntrack state. All the while, it holds the global netns lock. Given that I've bisected to the commit linked above which is to do with refcounting, I suspect that borked refcounting on conntrack entries makes them impossible to properly free/destroy, which prevents this worker from cleaning up the namespace, which then goes on to prevent anything else from interacting with namespaces (add/delete/etc). -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1403152 Title: unregister_netdevice: waiting for lo to become free. Usage count To manage notifications about this bug go to: https://bugs.launchpad.net/linux/+bug/1403152/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
