root@icarus:~# BUG: unable to handle kernel NULL pointer dereference at           (null)
IP: [<ffffffff811d69c4>] pin_remove+0x50/0xd7
PGD 0
Oops: 0002 [#1] SMP
Modules linked in:
CPU: 0 PID: 6771 Comm: lxc-autostart Not tainted 4.0.2-x86_64-linode56 #1
task: ffff880077682080 ti: ffff880063c6c000 task.ti: ffff880063c6c000
RIP: e030:[<ffffffff811d69c4>]  [<ffffffff811d69c4>] pin_remove+0x50/0xd7
RSP: e02b:ffff880063c6fe98  EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff880078148d20 RCX: dead000000100100
RDX: 0000000000000000 RSI: dead000000200200 RDI: ffffffff822bb828
RBP: ffff880063c6fee8 R08: 0000000300001e1e R09: 0000000000000000
R10: 0000000000000000 R11: ffff880078149e00 R12: ffff880077682080
R13: 00007ffe4e50b2f0 R14: 00007fc03748dcd0 R15: 00007ffe4e50b310
FS:  00007fc036268880(0000) GS:ffff88007d200000(0000) knlGS:ffff88007d200000
CS:  e033 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000007817b000 CR4: 0000000000042660
Stack:
 ffff880078148d20 ffffffff811c8bdd ffff880078148d20 ffffffff811d6b65
 ffff880063c6feb8 ffffffff81112678 ffff880079293900 ffffffff00000000
 ffff880077682080 ffffffff81103442 ffff880063c6fee8 ffff880063c6fee8
Call Trace:
 [<ffffffff811c8bdd>] ? drop_mountpoint+0x1a/0x27
 [<ffffffff811d6b65>] ? pin_kill+0x85/0x169
 [<ffffffff81112678>] ? __call_rcu.constprop.56+0x1da/0x1e3
 [<ffffffff81103442>] ? add_wait_queue+0x41/0x41
 [<ffffffff811d6c69>] ? mnt_pin_kill+0x20/0x24
 [<ffffffff811c8342>] ? cleanup_mnt+0x39/0x70
 [<ffffffff810ebe5c>] ? task_work_run+0x8d/0xa5
 [<ffffffff819024e3>] ? int_signal+0x12/0x17
Code: 48 89 50 08 48 b9 00 01 10 00 00 00 ad de 48 8b 43 20 48 be 00 02 20 00 00 00 ad de 48 8b 53 28 48 89 4b 30 48 89 73 38 48 85 c0 <48> 89 02 74 04 48 89 50 08 48 b8 00 01 10 00 00 00 ad de 48 c7
RIP  [<ffffffff811d69c4>] pin_remove+0x50/0xd7
 RSP <ffff880063c6fe98>
CR2: 0000000000000000
---[ end trace b115d4a2891b17d3 ]---
INFO: rcu_sched self-detected stall on CPU
        0: (17999 ticks this GP) idle=e31/140000000000001/0 softirq=13766/13766 fqs=8
         (t=18000 jiffies g=5390 c=5389 q=141)
rcu_sched kthread starved for 17984 jiffies!
Task dump for CPU 0:
lxc-autostart   R  running task        0  6771   6758 0x0000000a
 ffffffff82046d00 0000000000000000 ffffffff81110325 0000000000000000
 ffffffff82046d00 ffff88007d215640 ffff880063c6faa8 ffff88007d20e040
 ffffffff81112945 0000000000000000 ffffffff81901e3e 000000000000008d
Call Trace:
 <IRQ>  [<ffffffff81110325>] ? rcu_dump_cpu_stacks+0x5b/0x8e
 [<ffffffff81112945>] ? rcu_check_callbacks+0x231/0x61e
 [<ffffffff81901e3e>] ? _raw_spin_unlock_irqrestore+0x2e/0x3f
 [<ffffffff81122f8c>] ? tick_nohz_handler+0x92/0x92
 [<ffffffff811171e3>] ? update_process_times+0x2a/0x4e
 [<ffffffff81122e02>] ? tick_sched_handle+0x34/0x3f
 [<ffffffff81122fc0>] ? tick_sched_timer+0x34/0x5a
 [<ffffffff81117639>] ? __run_hrtimer+0xa1/0x15d
 [<ffffffff81117dfb>] ? hrtimer_interrupt+0xd1/0x1cf
 [<ffffffff81008e27>] ? xen_timer_interrupt+0x23/0xff
 [<ffffffff81610397>] ? add_interrupt_randomness+0x35/0x18e
 [<ffffffff8110a6b7>] ? handle_irq_event_percpu+0x4c/0x179
 [<ffffffff815e10cc>] ? info_for_irq+0xb/0x1b
 [<ffffffff8110d18f>] ? handle_percpu_irq+0x38/0x4f
 [<ffffffff8110a0d1>] ? generic_handle_irq+0x1a/0x25
 [<ffffffff815e3205>] ? evtchn_fifo_handle_events+0x13d/0x174
 [<ffffffff815e0ee7>] ? __xen_evtchn_do_upcall+0x3e/0x6e
 [<ffffffff815e2241>] ? xen_evtchn_do_upcall+0x2c/0x3b
 [<ffffffff81903e0e>] ? xen_do_hypervisor_callback+0x1e/0x40
 <EOI>  [<ffffffff810013aa>] ? xen_hypercall_sched_op+0xa/0x20
 [<ffffffff810013aa>] ? xen_hypercall_sched_op+0xa/0x20
 [<ffffffff815e1502>] ? xen_poll_irq_timeout+0x40/0x4c
 [<ffffffff8100e283>] ? xen_lock_spinning+0x96/0xe4
 [<ffffffff81902e34>] ? retint_restore_args+0x5/0x6
 [<ffffffff8100e175>] ? __raw_callee_save_xen_lock_spinning+0x11/0x1e
 [<ffffffff810d7fa9>] ? do_exit+0x3c4/0x947
 [<ffffffff810d7fa1>] ? do_exit+0x3bc/0x947
 [<ffffffff81901c7e>] ? _raw_spin_lock+0x3b/0x5e
 [<ffffffff811d6a69>] ? pin_insert_group+0x1e/0x7c
 [<ffffffff811c86bc>] ? umount_tree+0x1b4/0x22b
 [<ffffffff811c9d90>] ? drop_collected_mounts+0x35/0x4d
 [<ffffffff811cafbf>] ? put_mnt_ns+0x1d/0x28
 [<ffffffff810edaa0>] ? free_nsproxy+0x17/0x6a
 [<ffffffff810d7fc5>] ? do_exit+0x3e0/0x947
 [<ffffffff818f5d7c>] ? printk+0x4d/0x52
 [<ffffffff8101383c>] ? oops_end+0xc5/0xde
 [<ffffffff818f500e>] ? no_context+0x2f7/0x337
 [<ffffffff81904188>] ? page_fault+0x28/0x30
 [<ffffffff811d69c4>] ? pin_remove+0x50/0xd7
 [<ffffffff811d6989>] ? pin_remove+0x15/0xd7
 [<ffffffff811c8bdd>] ? drop_mountpoint+0x1a/0x27
 [<ffffffff811d6b65>] ? pin_kill+0x85/0x169
 [<ffffffff81112678>] ? __call_rcu.constprop.56+0x1da/0x1e3
 [<ffffffff81103442>] ? add_wait_queue+0x41/0x41
 [<ffffffff811d6c69>] ? mnt_pin_kill+0x20/0x24
 [<ffffffff811c8342>] ? cleanup_mnt+0x39/0x70
 [<ffffffff810ebe5c>] ? task_work_run+0x8d/0xa5
 [<ffffffff819024e3>] ? int_signal+0x12/0x17