Comment 3 for bug 1702910

With the sysctl net.ipv6.conf.all.disable_ipv6=1 we have still seen another kernel error as follows:

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[97989.224395] WARNING: CPU: 1 PID: 19570 at /build/linux-lts-xenial-ep3zLI/linux-lts-xenial-4.4.0/net/ipv6/addrconf_core.c:159 in6_dev_finish_destroy+0x6b/0xb0()
[97989.224456] CPU: 1 PID: 19570 Comm: kworker/u8:3 Not tainted 4.4.0-83-generic #106~14.04.1-Ubuntu
[97989.224457] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 09/17/2015
[97989.224462] Workqueue: netns cleanup_net
[97989.224463] 0000000000000000 ffff88011b75bbb8 ffffffff813ddefc 0000000000000000
[97989.224466] ffffffff81d7aa10 ffff88011b75bbf0 ffffffff8107ea36 ffff8800960e7c00
[97989.224467] ffff8800960e6c00 0000000000000006 ffff88011b75bcc0 0000000000000000
[97989.224469] Call Trace:
[97989.224474] [<ffffffff813ddefc>] dump_stack+0x63/0x87
[97989.224478] [<ffffffff8107ea36>] warn_slowpath_common+0x86/0xc0
[97989.224479] [<ffffffff8107eb2a>] warn_slowpath_null+0x1a/0x20
[97989.224481] [<ffffffff817e886b>] in6_dev_finish_destroy+0x6b/0xb0
[97989.224487] [<ffffffff817be120>] ip6_route_dev_notify+0x110/0x130
[97989.224490] [<ffffffff8109dd89>] notifier_call_chain+0x49/0x70
[97989.224492] [<ffffffff8109dea6>] raw_notifier_call_chain+0x16/0x20
[97989.224495] [<ffffffff81701d25>] call_netdevice_notifiers_info+0x35/0x60
[97989.224498] [<ffffffff8170c017>] netdev_run_todo+0x157/0x300
[97989.224500] [<ffffffff817172be>] rtnl_unlock+0xe/0x10
[97989.224502] [<ffffffff81704d88>] default_device_exit_batch+0x138/0x150
[97989.224507] [<ffffffff810bf4e0>] ? __wake_up_sync+0x20/0x20
[97989.224509] [<ffffffff816fd242>] ops_exit_list.isra.4+0x52/0x60
[97989.224510] [<ffffffff816fe213>] cleanup_net+0x1b3/0x280
[97989.224514] [<ffffffff81096d30>] process_one_work+0x150/0x3f0
[97989.224516] [<ffffffff810974aa>] worker_thread+0x11a/0x470
[97989.224518] [<ffffffff81097390>] ? rescuer_thread+0x310/0x310
[97989.224520] [<ffffffff8109cd66>] kthread+0xd6/0xf0
[97989.224523] [<ffffffff81081865>] ? do_exit+0x655/0xae0
[97989.224525] [<ffffffff8109cc90>] ? kthread_park+0x60/0x60
[97989.224527] [<ffffffff8180cc0f>] ret_from_fork+0x3f/0x70
[97989.224529] [<ffffffff8109cc90>] ? kthread_park+0x60/0x60
[97989.224530] ---[ end trace dfb865796f5b5681 ]---
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