And now we've got a second trace from the same machine with a bit more info:

And one more:

[14032.676085] general protection fault: 0000 [#1] SMP
[14032.678409] Modules linked in: isofs xt_CHECKSUM iptable_mangle ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack xt_tcpudp bridge stp llc iptable_filter ip_tables x_tables ppdev xen_fbfront fb_sys_fops intel_rapl iosf_mbi input_leds i2c_piix4 parport_pc 8250_fintek serio_raw parport mac_hid netconsole configfs autofs4 cirrus syscopyarea sysfillrect sysimgblt ttm crct10dif_pclmul crc32_pclmul aesni_intel drm_kms_helper aes_x86_64 lrw gf128mul glue_helper ablk_helper drm cryptd ixgbevf psmouse pata_acpi floppy
[14032.680061] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.2.0-23-generic #28-Ubuntu
[14032.680061] Hardware name: Xen HVM domU, BIOS 4.2.amazon 12/07/2015
[14032.680061] task: ffffffff81c13500 ti: ffffffff81c00000 task.ti: ffffffff81c00000
[14032.680061] RIP: 0010:[<ffffffff810e5c36>]  [<ffffffff810e5c36>] run_timer_softirq+0x116/0x2d0
[14032.680061] RSP: 0018:ffff8803ff203e98  EFLAGS: 00010086
[14032.680061] RAX: dead000000200200 RBX: ffff8803ff20e9c0 RCX: 00000000000e1785
[14032.680061] RDX: ffff8803ff203ec8 RSI: ffff8803ff21be00 RDI: ffff8803ff20e9c0
[14032.680061] RBP: ffff8803ff203f08 R08: 000000000001be00 R09: 0000000000000000
[14032.680061] R10: ffffea00036dc680 R11: 0000000000000000 R12: 00000000000000d2
[14032.680061] R13: ffffffff8172aaf0 R14: 0000000000000000 R15: ffff8800db71a3d0
[14032.680061] FS:  0000000000000000(0000) GS:ffff8803ff200000(0000) knlGS:0000000000000000
[14032.680061] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[14032.680061] CR2: 00007f97cd08ec64 CR3: 00000003f5834000 CR4: 00000000001406f0
[14032.680061] Stack:
[14032.680061]  ffff8803ff203eb8 ffff8803ff20f5f8 ffff8803ff20f3f8 ffff8803ff20f1f8
[14032.680061]  ffff8803ff20e9f8 ffff8800db71a348 dead000000200200 08c9e9276e6f82e9
[14032.680061]  0000000000011fc0 0000000000000001 ffffffff81c0b0c8 0000000000000001
[14032.680061] Call Trace:
[14032.680061]  <IRQ>
[14032.680061]  [<ffffffff8107f846>] __do_softirq+0xf6/0x250
[14032.680061]  [<ffffffff8107fb13>] irq_exit+0xa3/0xb0
[14032.680061]  [<ffffffff814a4499>] xen_evtchn_do_upcall+0x39/0x50
[14032.680061]  [<ffffffff817f1f6b>] xen_hvm_callback_vector+0x6b/0x70
[14032.680061]  <EOI>
[14032.680061]  [<ffffffff810e7542>] ? get_next_timer_interrupt+0xf2/0x240
[14032.680061]  [<ffffffff81060526>] ? native_safe_halt+0x6/0x10
[14032.680061]  [<ffffffff8101f1fe>] default_idle+0x1e/0xa0
[14032.680061]  [<ffffffff8101f9af>] arch_cpu_idle+0xf/0x20
[14032.680061]  [<ffffffff810bd4aa>] default_idle_call+0x2a/0x40
[14032.680061]  [<ffffffff810bd7e9>] cpu_startup_entry+0x2c9/0x320
[14032.680061]  [<ffffffff817dda2c>] rest_init+0x7c/0x80
[14032.680061]  [<ffffffff81d50025>] start_kernel+0x48b/0x4ac
[14032.680061]  [<ffffffff81d4f120>] ? early_idt_handler_array+0x120/0x120
[14032.680061]  [<ffffffff81d4f339>] x86_64_start_reservations+0x2a/0x2c
[14032.680061]  [<ffffffff81d4f485>] x86_64_start_kernel+0x14a/0x16d
[14032.680061] Code: 81 e6 00 00 20 00 48 85 d2 48 89 45 b8 0f 85 30 01 00 00 4c 89 7b 08 0f 1f 44 00 00 49 8b 07 49 8b 57 08 48 85 c0 48 89 02 74 04 <48> 89 50 08 41 f6 47 2a 10 48 b8 00 02 20 00 00 00 ad de 49 c7
[14032.680061] RIP  [<ffffffff810e5c36>] run_timer_softirq+0x116/0x2d0
[14032.680061]  RSP <ffff8803ff203e98>