Aha the full log show better stuff: [ 0.033227] core perfctr but no constraints; unknown hardware! Loading, please wait... /dev/vda1: recovering journal /dev/vda1: clean, 34205/131072 files, 234418/524032 blocks [ 0.911703] ------------[ cut here ]------------ [ 0.913782] kernel BUG at /build/linux-hWOm3y/linux-3.16.56/arch/x86/kernel/alternative.c:694! [ 0.915169] invalid opcode: 0000 [#1] SMP [ 0.915169] Modules linked in: autofs4 ext4 crc16 mbcache jbd2 ata_generic virtio_net virtio_blk ata_piix crct10dif_pclmul crct10dif_common crc32c_intel psmouse uhci_hcd libata floppy i2c_piix4 ehci_hcd scsi_mod i2c_core usbcore usb_common virtio_pci virtio_ring virtio [ 0.928102] CPU: 0 PID: 155 Comm: kworker/0:2 Not tainted 3.16.0-6-amd64 #1 Debian 3.16.56-1+deb8u1 [ 0.928102] Hardware name: OpenStack Foundation OpenStack Nova, BIOS 1.15.0-1 04/01/2014 [ 0.928102] Workqueue: events netstamp_clear [ 0.928102] task: ffff880000060c30 ti: ffff88007f9f8000 task.ti: ffff88007f9f8000 [ 0.928102] RIP: 0010:[] [] text_poke+0x1c7/0x270 [ 0.928102] RSP: 0018:ffff88007f9fbd60 EFLAGS: 00010897 [ 0.928102] RAX: 00000000000000cc RBX: 0000000000000800 RCX: 00000000fffa3203 [ 0.928102] RDX: 00000000078bfbff RSI: 0000000000000000 RDI: ffffffffff57a000 [ 0.928102] RBP: ffffffff81440fbf R08: ffff880000000000 R09: 0000000000000090 [ 0.928102] R10: 8080808080808080 R11: fefefefefefefeff R12: 0000000000000001 [ 0.928102] R13: ffff88007f9fbda7 R14: 0000160000000000 R15: ffffea0000046e38 [ 0.928102] FS: 0000000000000000(0000) GS:ffff88007ee00000(0000) knlGS:0000000000000000 [ 0.928102] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 0.928102] CR2: 000055c9b156de40 CR3: 000000007f97d000 CR4: 00000000003606f0 [ 0.928102] Stack: [ 0.928102] 0000000000000286 ffffffff81440fbf 0000000000000005 ffff88007f9fbdd3 [ 0.928102] ffffffff81440fc0 ffff88007ee17100 0000000000000000 ffffffff8101c695 [ 0.928102] ccff880000060c98 ffffffff81440fbf ffff88007f9fbdd3 ffffffff816029c4 [ 0.928102] Call Trace: [ 0.928102] [] ? dev_queue_xmit_nit+0x10f/0x220 [ 0.928102] [] ? dev_queue_xmit_nit+0x110/0x220 [ 0.928102] [] ? text_poke_bp+0x45/0xc0 [ 0.928102] [] ? dev_queue_xmit_nit+0x10f/0x220 [ 0.928102] [] ? arch_jump_label_transform+0x8c/0x100 [ 0.928102] [] ? __jump_label_update+0x57/0x70 [ 0.928102] [] ? static_key_slow_inc+0xbd/0xc0 [ 0.928102] [] ? process_one_work+0x14c/0x470 [ 0.928102] [] ? worker_thread+0x6b/0x540 [ 0.928102] [] ? __schedule+0x284/0x740 [ 0.928102] [] ? rescuer_thread+0x2d0/0x2d0 [ 0.928102] [] ? kthread+0xd1/0xf0 [ 0.928102] [] ? do_exit+0x847/0xac0 [ 0.928102] [] ? kthread_create_on_node+0x180/0x180 [ 0.928102] [] ? ret_from_fork+0x5b/0xa0 [ 0.928102] [] ? kthread_create_on_node+0x180/0x180 [ 0.928102] Code: 41 0f b6 45 00 38 45 00 75 21 31 c0 0f 1f 84 00 00 00 00 00 83 c0 01 48 63 c8 49 39 cc 76 3d 41 0f b6 54 0d 00 38 54 0d 00 74 e9 <0f> 0b 0f 1f 80 00 00 00 00 48 89 ef e8 18 68 16 00 48 8d bd 00 [ 0.928102] RIP [] text_poke+0x1c7/0x270 [ 0.928102] RSP [ 0.928102] ---[ end trace aed2ee8e2725bd9a ]--- [ 1.009625] BUG: unable to handle kernel paging request at ffffffffffffffd8 [ 1.011130] IP: [] kthread_data+0xc/0x20 [ 1.012004] PGD 1817067 PUD 1819067 PMD 0 [ 1.012004] Oops: 0000 [#2] SMP [ 1.012004] Modules linked in: autofs4 ext4 crc16 mbcache jbd2 ata_generic virtio_net virtio_blk ata_piix crct10dif_pclmul crct10dif_common crc32c_intel psmouse uhci_hcd libata floppy i2c_piix4 ehci_hcd scsi_mod i2c_core usbcore usb_common virtio_pci virtio_ring virtio [ 1.012004] CPU: 0 PID: 155 Comm: kworker/0:2 Tainted: G D 3.16.0-6-amd64 #1 Debian 3.16.56-1+deb8u1 [ 1.012004] Hardware name: OpenStack Foundation OpenStack Nova, BIOS 1.15.0-1 04/01/2014 [ 1.012004] task: ffff880000060c30 ti: ffff88007f9f8000 task.ti: ffff88007f9f8000 [ 1.012004] RIP: 0010:[] [] kthread_data+0xc/0x20 [ 1.012004] RSP: 0018:ffff88007f9fbb08 EFLAGS: 00010002 [ 1.012004] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000002 [ 1.012004] RDX: 000000000000000e RSI: 0000000000000000 RDI: ffff880000060c30 [ 1.012004] RBP: ffff880000060c30 R08: 0000000000000000 R09: 000000000000001f [ 1.012004] R10: ffff88007f9fbb08 R11: 0000000000000000 R12: ffff88007ee13fc0 [ 1.012004] R13: ffff880000061098 R14: 0000000000000000 R15: ffffea0000046e38 [ 1.012004] FS: 0000000000000000(0000) GS:ffff88007ee00000(0000) knlGS:0000000000000000 [ 1.012004] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1.012004] CR2: 0000000000000028 CR3: 000000007c123000 CR4: 00000000003606f0 [ 1.012004] Stack: [ 1.012004] ffffffff810874ed 0000000000000000 ffffffff81535a10 0000000000013fc0 [ 1.012004] ffff88007f9fbfd8 0000000000013fc0 ffff880000060c30 ffff8800000612c0 [ 1.012004] ffff880000060c20 ffff88007e7b92d0 0000000000000001 ffff880000060c30 [ 1.012004] Call Trace: [ 1.012004] [] ? wq_worker_sleeping+0xd/0x90 [ 1.012004] [] ? __schedule+0x5f0/0x740 [ 1.012004] [] ? do_exit+0x847/0xac0 [ 1.012004] [] ? oops_end+0x97/0xe0 [ 1.012004] [] ? do_error_trap+0x70/0xe0 [ 1.012004] [] ? text_poke+0x1c7/0x270 [ 1.012004] [] ? select_task_rq_fair+0x36d/0x6e0 [ 1.012004] [] ? dev_queue_xmit_nit+0x10f/0x220 [ 1.012004] [] ? invalid_op+0x1e/0x30 [ 1.012004] [] ? dev_queue_xmit_nit+0x10f/0x220 [ 1.012004] [] ? text_poke+0x1c7/0x270 [ 1.012004] [] ? dev_queue_xmit_nit+0x10f/0x220 [ 1.012004] [] ? dev_queue_xmit_nit+0x110/0x220 [ 1.012004] [] ? text_poke_bp+0x45/0xc0 [ 1.012004] [] ? dev_queue_xmit_nit+0x10f/0x220 [ 1.012004] [] ? arch_jump_label_transform+0x8c/0x100 [ 1.012004] [] ? __jump_label_update+0x57/0x70 [ 1.012004] [] ? static_key_slow_inc+0xbd/0xc0 [ 1.012004] [] ? process_one_work+0x14c/0x470 [ 1.012004] [] ? worker_thread+0x6b/0x540 [ 1.012004] [] ? __schedule+0x284/0x740 [ 1.012004] [] ? rescuer_thread+0x2d0/0x2d0 [ 1.012004] [] ? kthread+0xd1/0xf0 [ 1.012004] [] ? do_exit+0x847/0xac0 [ 1.012004] [] ? kthread_create_on_node+0x180/0x180 [ 1.012004] [] ? ret_from_fork+0x5b/0xa0 [ 1.012004] [] ? kthread_create_on_node+0x180/0x180 [ 1.012004] Code: 10 04 00 00 48 8b 40 c8 48 c1 e8 02 83 e0 01 c3 66 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 66 66 66 66 90 48 8b 87 10 04 00 00 <48> 8b 40 d8 c3 66 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 66 [ 1.012004] RIP [] kthread_data+0xc/0x20 [ 1.012004] RSP [ 1.012004] CR2: ffffffffffffffd8 [ 1.012004] ---[ end trace aed2ee8e2725bd9b ]--- [ 1.012004] Fixing recursive fault but reboot is needed!