I can't be sure that we ran into the exact same bug, but Amazon seems to think we may have. I can't find the beginning of the console log, but here's a mid-point that shows the hang:

Host Type: Amazon EC2 r3.8xlarge
OS: Ubuntu 14.04.5
Kernel: 3.13.0-93-generic
Networking: Intel Enhanced Neworking driver 2.16.4 (ixgbevf)

Workload: Postgres running with most of the systems memory, but Apache Flume was going a bit haywire at the time taking ~20-30% of the available CPU (using Oracle Java 7).

[27484.664087] Code: cc cc cc b8 1c 00 00 00 0f 01 c1 c3 cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc b8 1d 00 00 00 0f 01 c1 <c3> cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc 
[27504.324077] BUG: soft lockup - CPU#2 stuck for 22s! [java:62266]
[27504.324077] Modules linked in: ipt_REJECT xt_multiport nf_conntrack_ipv4 nf_defrag_ipv4 xt_comment xt_conntrack nf_conntrack ip6table_filter ip6_tables iptable_filter ip_tables x_tables bcache dm_crypt syscopyarea[27504.344088] BUG: soft lockup - CPU#3 stuck for 22s! [java:62269]
[27504.344088] Modules linked in: ipt_REJECT xt_multiport nf_conntrack_ipv4 nf_defrag_ipv4 xt_comment xt_conntrack nf_conntrack ip6table_filter ip6_tables iptable_filter ip_tables x_tables bcache dm_crypt syscopyarea sysfillrect sysimgblt fb_sys_fops serio_raw isofs raid10 raid456 async_memcpy async_raid6_recov async_pq async_xor async_tx xor raid6_pq raid1 raid0 multipath linear crct10dif_pclmul crc32_pclmul aesni_intel aes_x86_64 lrw gf128mul glue_helper ablk_helper cryptd psmouse floppy ixgbevf(OX)
[27504.344088] CPU: 3 PID: 62269 Comm: java Tainted: G      D    OX 3.13.0-93-generic #140-Ubuntu
[27504.344088] Hardware name: Xen HVM domU, BIOS 4.2.amazon 05/12/2016
[27504.344088] task: ffff883c70a31800 ti: ffff8837955e0000 task.ti: ffff8837955e0000
[27504.344088] RIP: 0010:[<ffffffff810013a8>]  [<ffffffff810013a8>] xen_hypercall_sched_op+0x8/0x20
[27504.344088] RSP: 0000:ffff8837955e1c60  EFLAGS: 00000202
[27504.344088] RAX: 0000000000000000 RBX: ffff8837955e1c40 RCX: 00000000fffffffa
[27504.344088] RDX: 0000000000000000 RSI: ffff8837955e1c70 RDI: 0000000000000003
[27504.344088] RBP: ffff8837955e1c90 R08: ffff881e1980f800 R09: ffff881e19400470
[27504.344088] R10: 0000000000000019 R11: 8000001161833966 R12: 0000000000001000
[27504.344088] R13: ffff883c70778340 R14: 0000000000000000 R15: 0000000000000000
[27504.344088] FS:  00007f0b9c7d7700(0000) GS:ffff881e19c60000(0000) knlGS:0000000000000000
[27504.344088] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[27504.344088] CR2: 000000070809b000 CR3: 00000013bdca0000 CR4: 00000000001406e0
[27504.344088] Stack:
[27504.344088]  ffffffff81438b2e 0000003b810c1ec7 ffff8837955e1c6c ffffffff00000001
[27504.344088]  0000000000000000 ffff881e19c6afe0 ffff8837955e1ca0 ffffffff8143aab0
[27504.344088]  ffff8837955e1ce8 ffffffff81011fa3 0000000000000213 00003eba955e1d40
[27504.344088] Call Trace:
[27504.344088]  [<ffffffff81438b2e>] ? xen_poll_irq_timeout+0x3e/0x50
[27504.344088]  [<ffffffff8143aab0>] xen_poll_irq+0x10/0x20
[27504.344088]  [<ffffffff81011fa3>] xen_lock_spinning+0xa3/0x100
[27504.344088]  [<ffffffff81011e61>] __raw_callee_save_xen_lock_spinning+0x11/0x20
[27504.344088]  [<ffffffff81731ea8>] ? _raw_spin_lock+0x48/0x50
[27504.344088]  [<ffffffff8117bffa>] do_numa_page+0x5a/0x1b0
[27504.344088]  [<ffffffff8117d2af>] handle_mm_fault+0x5ff/0xf00
[27504.344088]  [<ffffffff811d4d08>] ? filldir+0x88/0x100
[27504.344088]  [<ffffffff81736004>] __do_page_fault+0x184/0x560
[27504.344088]  [<ffffffff811d4b3c>] ? iterate_dir+0x7c/0xe0
[27504.344088]  [<ffffffff817363fa>] do_page_fault+0x1a/0x70
[27504.344088]  [<ffffffff81732728>] page_fault+0x28/0x30
```