Comment 6 for bug 1586838

v4.7-rc2 kernel (http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.7-rc2-yakkety/) sees the same issue:

[ 70.064983] kernel BUG at /home/kernel/COD/linux/drivers/md/bcache/super.c:1822!
[ 70.065214] invalid opcode: 0000 [#1] SMP
[ 70.065355] Modules linked in: fuse ppdev input_leds lpc_ich intel_powerclamp led_class joydev serio_raw parport_pc sg i2c_piix4 ac battery parport mac_hid acpi_cpufreq ib_iser rdma_cm iw_cm ib_cm ib_core configfs iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi autofs4 btrfs raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c raid1 multipath linear bcache raid0 md_mod sr_mod cdrom sd_mod ata_generic pata_acpi hid_generic usbhid hid ohci_pci crct10dif_pclmul virtio_net crc32_pclmul crc32c_intel ghash_clmulni_intel aesni_intel ahci aes_x86_64 lrw gf128mul libahci glue_helper ablk_helper cryptd ohci_hcd ehci_pci ata_piix ehci_hcd libata usbcore scsi_mod psmouse usb_common fjes virtio_pci virtio_ring virtio video button jitterentropy_rng drbg ansi_cprng

[ 70.071156] CPU: 3 PID: 1557 Comm: bcache-register Not tainted 4.7.0-040700rc2-generic #201606051831
[ 70.071417] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
[ 70.071655] task: ffff8800775f0000 ti: ffff88007bf84000 task.ti: ffff88007bf84000
[ 70.072051] RIP: 0010:[<ffffffffc02e4ff6>] [<ffffffffc02e4ff6>] cache_alloc.isra.21+0x646/0x670 [bcache]
[ 70.072757] RSP: 0018:ffff88007bf87d18 EFLAGS: 00010246
[ 70.073129] RAX: ffff88007757b070 RBX: ffff88007c228000 RCX: 00000000000007f8
[ 70.073516] RDX: 00000000000007f7 RSI: 0000000000000000 RDI: ffff88007d003b80
[ 70.073902] RBP: ffff88007bf87d30 R08: ffff88007fd99f40 R09: ffff88007d003b80
[ 70.074288] R10: ffff88007757b070 R11: 0000000000000040 R12: 0000000000000000
[ 70.074674] R13: 0000000000000010 R14: ffff88007b2308f0 R15: ffff880078479000
[ 70.075061] FS: 00007f2bd2778700(0000) GS:ffff88007fd80000(0000) knlGS:0000000000000000
[ 70.075708] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 70.076064] CR2: 00007f2bd21e1130 CR3: 0000000079a4b000 CR4: 00000000000406e0
[ 70.076452] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 70.076854] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 70.077267] Stack:
[ 70.077565] ffff880035568340 ffffea0001efbcc0 ffff88007c228000 ffff88007bf87dd0
[ 70.078547] ffffffffc02e83f9 ffff88007952b500 ffff880035648f00 000000000000005b
[ 70.079455] 0000000000000080 ffff88007c228008 ffff88007757b080 0000000000000009
[ 70.081160] Call Trace:
[ 70.081755] [<ffffffffc02e83f9>] register_bcache+0x2d9/0x1190 [bcache]
[ 70.082165] [<ffffffff813cabcf>] kobj_attr_store+0xf/0x20
[ 70.082530] [<ffffffff813cabcf>] ? kobj_attr_store+0xf/0x20
[ 70.082902] [<ffffffff812a5ce7>] sysfs_kf_write+0x37/0x40
[ 70.083278] [<ffffffff812a5058>] kernfs_fop_write+0x118/0x1a0
[ 70.083635] [<ffffffff81222287>] __vfs_write+0x37/0x160
[ 70.083977] [<ffffffff81370188>] ? apparmor_file_permission+0x18/0x20
[ 70.084349] [<ffffffff8133084d>] ? security_file_permission+0x3d/0xc0
[ 70.084721] [<ffffffff810cb912>] ? percpu_down_read+0x12/0x50
[ 70.085075] [<ffffffff812235e8>] vfs_write+0xb8/0x1b0
[ 70.085412] [<ffffffff81224a85>] SyS_write+0x55/0xc0
[ 70.086226] [<ffffffff81719d36>] entry_SYSCALL_64_fastpath+0x1e/0xa8
[ 70.086631] Code: 6a fd ff ff e9 4d fd ff ff be c0 00 40 02 4c 89 e7 e8 bf aa f1 c0 48 85 c0 48 89 83 f0 0a 00 00 0f 85 96 fd ff ff e9 79 fd ff ff <0f> 0b 0f 0b 0f 0b bf 40 00 00 00 e8 2a a2 ef c0 48 85 c0 48 89
[ 70.090234] RIP [<ffffffffc02e4ff6>] cache_alloc.isra.21+0x646/0x670 [bcache]
[ 70.090848] RSP <ffff88007bf87d18>
[ 70.091365] ---[ end trace 241fa6e06ca0e7af ]---