Comment 15 for bug 1729637

Thanks for the fast reply.

I tried both kernels and was not able to trigger an Oops.

On the 4.4.0-98.121~lp1729637-generic kernel a hung task warning happened:

[ +0.750497] unregister_netdevice: waiting for lo to become free. Usage count = 1
[ +0.992665] aufs au_opts_verify:1597:dockerd[1620]: dirperm1 breaks the protection by the permission bits on the lower branch
[ +0.016910] aufs au_opts_verify:1597:dockerd[1620]: dirperm1 breaks the protection by the permission bits on the lower branch
[ +0.015247] aufs au_opts_verify:1597:dockerd[1592]: dirperm1 breaks the protection by the permission bits on the lower branch
[ +0.006387] device veth7d3bee3 entered promiscuous mode
[ +0.000923] IPv6: ADDRCONF(NETDEV_UP): veth7d3bee3: link is not ready
[ +9.051406] unregister_netdevice: waiting for lo to become free. Usage count = 1
[ +10.067531] unregister_netdevice: waiting for lo to become free. Usage count = 1
[ +10.083551] unregister_netdevice: waiting for lo to become free. Usage count = 1
[Nov 3 18:53] unregister_netdevice: waiting for lo to become free. Usage count = 1
[ +8.055656] INFO: task exe:2868 blocked for more than 120 seconds.
[ +0.006363] Not tainted 4.4.0-98-generic #121~lp1729637
[ +0.005970] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ +0.008347] exe D ffff88012a0e3cb8 0 2868 1 0x00000000
[ +0.000006] ffff88012a0e3cb8 ffffffff821db9a0 ffffffff81e11500 ffff8800ba25f000
[ +0.000002] ffff88012a0e4000 ffffffff81ef7a64 ffff8800ba25f000 00000000ffffffff
[ +0.000002] ffffffff81ef7a68 ffff88012a0e3cd0 ffffffff818405d5 ffffffff81ef7a60
[ +0.000002] Call Trace:
[ +0.000011] [<ffffffff818405d5>] schedule+0x35/0x80
[ +0.000004] [<ffffffff8184087e>] schedule_preempt_disabled+0xe/0x10
[ +0.000003] [<ffffffff818424b9>] __mutex_lock_slowpath+0xb9/0x130
[ +0.000002] [<ffffffff8184254f>] mutex_lock+0x1f/0x30
[ +0.000007] [<ffffffff8172ea8e>] copy_net_ns+0x6e/0x120
[ +0.000010] [<ffffffff810a172b>] create_new_namespaces+0x11b/0x1d0
[ +0.000001] [<ffffffff810a184d>] copy_namespaces+0x6d/0xa0
[ +0.000005] [<ffffffff8107f1d2>] copy_process+0x8e2/0x1b30
[ +0.000003] [<ffffffff810805b0>] _do_fork+0x80/0x360
[ +0.000002] [<ffffffff81080939>] SyS_clone+0x19/0x20
[ +0.000004] [<ffffffff818446f2>] entry_SYSCALL_64_fastpath+0x16/0x71
[ +1.999139] unregister_netdevice: waiting for lo to become free. Usage count = 1