** Changed in: linux (Ubuntu Trusty)
Status: In Progress => Fix Committed
--
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/1466135
Title:
nf_conntrack releases a conntrack with non-zero refcnt
Status in linux package in Ubuntu:
Fix Released
Status in linux source package in Trusty:
Fix Committed
Bug description:
[Impact]
Occasionally starting new containers or creating new net namespaces may soft
lockup because of improper refcounting of conntrack entires.
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 commit e53376bef2cd97d3e3f61fdc677fb8da7d03d0da 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).
[Test Case]
bug 1403152 has a testcase which can occasionally hit this issue
[Fix]
$ git describe --contains e53376bef2cd97d3e3f61fdc677fb8da7d03d0da
v3.14-rc3~36^2~28^2~12
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1466135/+subscriptions
--
Mailing list: https://launchpad.net/~kernel-packages
Post to : [email protected]
Unsubscribe : https://launchpad.net/~kernel-packages
More help : https://help.launchpad.net/ListHelp
