The following tracebacks are observed when running trybot on guado-paladin.

018-10-16T19:01:35.042040+00:00 INFO session_manager[873]: [INFO:upstart_signal_emitter.cc(35)] Emitting ash-initialized Upstart signal
2018-10-16T19:01:36.605100+00:00 WARNING kernel: [   15.727706] WARNING: CPU: 3 PID: 1092 at ../../../../../tmp/portage/sys-kernel/chromeos-kernel-next-4.19-r1/work/chromeos-kernel-next-4.19/drivers/gpu/drm/drm_gem.c:893 drm_gem_object_put+0x1e/0x28
2018-10-16T19:01:36.605111+00:00 WARNING kernel: [   15.727711] Modules linked in: cfg80211 uvcvideo videobuf2_vmalloc videobuf2_memops videobuf2_v4l2 videobuf2_common joydev snd_usb_audio snd_usbmidi_lib snd_hwdep snd_rawmidi hid_multitouch snd_seq_device smsc95xx usbnet mii
2018-10-16T19:01:36.605113+00:00 WARNING kernel: [   15.727728] CPU: 3 PID: 1092 Comm: DrmThread Not tainted 4.19.0-rc8-00841-g61dc60e1aac4 #1
2018-10-16T19:01:36.605114+00:00 WARNING kernel: [   15.727730] Hardware name: GOOGLE Guado, BIOS Google_Guado.6301.108.4 04/01/2015
2018-10-16T19:01:36.605115+00:00 WARNING kernel: [   15.727735] RIP: 0010:drm_gem_object_put+0x1e/0x28
2018-10-16T19:01:36.605226+00:00 WARNING kernel: [   15.727739] Code: 59 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f 1f 44 00 00 55 48 89 e5 48 85 ff 74 18 48 8b 47 08 48 8b 40 68 48 a9 f8 ff ff ff 75 02 <0f> 0b 5d e9 85 fb ff ff 5d c3 0f 1f 44 00 00 55 48 c7 c2 f2 12 f3
2018-10-16T19:01:36.605230+00:00 WARNING kernel: [   15.727741] RSP: 0018:ffffb2c1c0637cd0 EFLAGS: 00010246
2018-10-16T19:01:36.605231+00:00 WARNING kernel: [   15.727745] RAX: 0000000000000000 RBX: ffff924574504800 RCX: 0000000000000000
2018-10-16T19:01:36.605231+00:00 WARNING kernel: [   15.727747] RDX: 0000000100000000 RSI: ffff92457a32b4f0 RDI: ffff924574504800
2018-10-16T19:01:36.605232+00:00 WARNING kernel: [   15.727749] RBP: ffffb2c1c0637cd0 R08: 0000000000000000 R09: 0000000000000000
2018-10-16T19:01:36.605233+00:00 WARNING kernel: [   15.727752] R10: ffff92454d9d3dd8 R11: 0000000000000000 R12: ffff924575dca020
2018-10-16T19:01:36.605234+00:00 WARNING kernel: [   15.727754] R13: ffffb2c1c0637db0 R14: 0000000000000001 R15: 0000000000000030
2018-10-16T19:01:36.605235+00:00 WARNING kernel: [   15.727757] FS:  00007ff01d900700(0000) GS:ffff92457ab80000(0000) knlGS:0000000000000000
2018-10-16T19:01:36.605236+00:00 WARNING kernel: [   15.727760] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
2018-10-16T19:01:36.605236+00:00 WARNING kernel: [   15.727762] CR2: 000059cfc8493f40 CR3: 0000000174b28006 CR4: 00000000003606e0
2018-10-16T19:01:36.605237+00:00 WARNING kernel: [   15.727764] Call Trace:
2018-10-16T19:01:36.605238+00:00 WARNING kernel: [   15.727771]  udl_gem_mmap+0x72/0x8d
2018-10-16T19:01:36.605239+00:00 WARNING kernel: [   15.727777]  ? drm_mode_create_dumb_ioctl+0xf/0xf
2018-10-16T19:01:36.605240+00:00 WARNING kernel: [   15.727781]  drm_ioctl_kernel+0x8d/0xe4
2018-10-16T19:01:36.605240+00:00 WARNING kernel: [   15.727786]  drm_ioctl+0x294/0x39d
2018-10-16T19:01:36.605241+00:00 WARNING kernel: [   15.727790]  ? drm_mode_create_dumb_ioctl+0xf/0xf
2018-10-16T19:01:36.605242+00:00 WARNING kernel: [   15.727795]  ? __inode_security_revalidate+0x36/0x6c
2018-10-16T19:01:36.605243+00:00 WARNING kernel: [   15.727800]  vfs_ioctl+0x21/0x2f
2018-10-16T19:01:36.605244+00:00 WARNING kernel: [   15.727804]  do_vfs_ioctl+0x4e7/0x50a
2018-10-16T19:01:36.605245+00:00 WARNING kernel: [   15.727808]  ksys_ioctl+0x55/0x75
2018-10-16T19:01:36.605245+00:00 WARNING kernel: [   15.727812]  __x64_sys_ioctl+0x1a/0x1e
2018-10-16T19:01:36.605246+00:00 WARNING kernel: [   15.727816]  do_syscall_64+0x54/0x64
2018-10-16T19:01:36.605247+00:00 WARNING kernel: [   15.727821]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
2018-10-16T19:01:36.605248+00:00 WARNING kernel: [   15.727825] RIP: 0033:0x7ff020980967
2018-10-16T19:01:36.605249+00:00 WARNING kernel: [   15.727828] Code: 8a 66 90 48 8b 05 29 55 2b 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d f9 54 2b 00 f7 d8 64 89 01 48
2018-10-16T19:01:36.605250+00:00 WARNING kernel: [   15.727831] RSP: 002b:00007ff01d8ff048 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
2018-10-16T19:01:36.605251+00:00 WARNING kernel: [   15.727834] RAX: ffffffffffffffda RBX: 000022a20e970000 RCX: 00007ff020980967
2018-10-16T19:01:36.605252+00:00 WARNING kernel: [   15.727837] RDX: 00007ff01d8ff080 RSI: 00000000c01064b3 RDI: 0000000000000028
2018-10-16T19:01:36.605252+00:00 WARNING kernel: [   15.727839] RBP: 00007ff01d8ff070 R08: 0000000000000001 R09: 000022a20f4f2bd8
2018-10-16T19:01:36.605253+00:00 WARNING kernel: [   15.727841] R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000028
2018-10-16T19:01:36.605254+00:00 WARNING kernel: [   15.727844] R13: 000022a20e970000 R14: 00007ff01d8ff080 R15: 00000000c01064b3
2018-10-16T19:01:36.605255+00:00 WARNING kernel: [   15.727848] ---[ end trace 66cd23cb4725d107 ]---
2018-10-16T19:01:36.605255+00:00 WARNING kernel: [   15.727884] WARNING: CPU: 3 PID: 1092 at ../../../../../tmp/portage/sys-kernel/chromeos-kernel-next-4.19-r1/work/chromeos-kernel-next-4.19/drivers/gpu/drm/drm_gem.c:893 drm_gem_object_put+0x1e/0x28
2018-10-16T19:01:36.605256+00:00 WARNING kernel: [   15.727887] Modules linked in: cfg80211 uvcvideo videobuf2_vmalloc videobuf2_memops videobuf2_v4l2 videobuf2_common joydev snd_usb_audio snd_usbmidi_lib snd_hwdep snd_rawmidi hid_multitouch snd_seq_device smsc95xx usbnet mii
2018-10-16T19:01:36.605257+00:00 WARNING kernel: [   15.727901] CPU: 3 PID: 1092 Comm: DrmThread Tainted: G        W         4.19.0-rc8-00841-g61dc60e1aac4 #1
2018-10-16T19:01:36.605258+00:00 WARNING kernel: [   15.727903] Hardware name: GOOGLE Guado, BIOS Google_Guado.6301.108.4 04/01/2015
2018-10-16T19:01:36.605259+00:00 WARNING kernel: [   15.727907] RIP: 0010:drm_gem_object_put+0x1e/0x28
2018-10-16T19:01:36.605260+00:00 WARNING kernel: [   15.727910] Code: 59 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f 1f 44 00 00 55 48 89 e5 48 85 ff 74 18 48 8b 47 08 48 8b 40 68 48 a9 f8 ff ff ff 75 02 <0f> 0b 5d e9 85 fb ff ff 5d c3 0f 1f 44 00 00 55 48 c7 c2 f2 12 f3
2018-10-16T19:01:36.605261+00:00 WARNING kernel: [   15.727913] RSP: 0018:ffffb2c1c0637cd0 EFLAGS: 00010246
2018-10-16T19:01:36.605262+00:00 WARNING kernel: [   15.727916] RAX: 0000000000000000 RBX: ffff924574505200 RCX: 0000000000000000
2018-10-16T19:01:36.605263+00:00 WARNING kernel: [   15.727918] RDX: 0000000100004000 RSI: ffff92457a32b4f0 RDI: ffff924574505200
2018-10-16T19:01:36.605263+00:00 WARNING kernel: [   15.727921] RBP: ffffb2c1c0637cd0 R08: 0000000000000000 R09: 0000000000000000
2018-10-16T19:01:36.605264+00:00 WARNING kernel: [   15.727923] R10: ffff92454d9d3700 R11: 0000000000000000 R12: ffff924575dca020
2018-10-16T19:01:36.605265+00:00 WARNING kernel: [   15.727925] R13: ffffb2c1c0637db0 R14: 0000000000000002 R15: 0000000000000030
2018-10-16T19:01:36.605266+00:00 WARNING kernel: [   15.727928] FS:  00007ff01d900700(0000) GS:ffff92457ab80000(0000) knlGS:0000000000000000
2018-10-16T19:01:36.605267+00:00 WARNING kernel: [   15.727931] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
2018-10-16T19:01:36.605268+00:00 WARNING kernel: [   15.727933] CR2: 000059cfc8493f40 CR3: 0000000174b28006 CR4: 00000000003606e0
2018-10-16T19:01:36.605269+00:00 WARNING kernel: [   15.727935] Call Trace:
2018-10-16T19:01:36.605270+00:00 WARNING kernel: [   15.727940]  udl_gem_mmap+0x72/0x8d
2018-10-16T19:01:36.605271+00:00 WARNING kernel: [   15.727944]  ? drm_mode_create_dumb_ioctl+0xf/0xf
2018-10-16T19:01:36.605272+00:00 WARNING kernel: [   15.727948]  drm_ioctl_kernel+0x8d/0xe4
2018-10-16T19:01:36.605272+00:00 WARNING kernel: [   15.727953]  drm_ioctl+0x294/0x39d
2018-10-16T19:01:36.605273+00:00 WARNING kernel: [   15.727957]  ? drm_mode_create_dumb_ioctl+0xf/0xf
2018-10-16T19:01:36.605274+00:00 WARNING kernel: [   15.727961]  ? __inode_security_revalidate+0x36/0x6c
2018-10-16T19:01:36.605275+00:00 WARNING kernel: [   15.727966]  vfs_ioctl+0x21/0x2f
2018-10-16T19:01:36.605275+00:00 WARNING kernel: [   15.727970]  do_vfs_ioctl+0x4e7/0x50a
2018-10-16T19:01:36.605276+00:00 WARNING kernel: [   15.727974]  ksys_ioctl+0x55/0x75
2018-10-16T19:01:36.605277+00:00 WARNING kernel: [   15.727978]  __x64_sys_ioctl+0x1a/0x1e
2018-10-16T19:01:36.605277+00:00 WARNING kernel: [   15.727981]  do_syscall_64+0x54/0x64
2018-10-16T19:01:36.605278+00:00 WARNING kernel: [   15.727985]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
2018-10-16T19:01:36.605279+00:00 WARNING kernel: [   15.727989] RIP: 0033:0x7ff020980967
2018-10-16T19:01:36.605280+00:00 WARNING kernel: [   15.727992] Code: 8a 66 90 48 8b 05 29 55 2b 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d f9 54 2b 00 f7 d8 64 89 01 48
2018-10-16T19:01:36.605281+00:00 WARNING kernel: [   15.727994] RSP: 002b:00007ff01d8ff048 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
2018-10-16T19:01:36.605281+00:00 WARNING kernel: [   15.727997] RAX: ffffffffffffffda RBX: 000022a20e970000 RCX: 00007ff020980967
2018-10-16T19:01:36.605282+00:00 WARNING kernel: [   15.728000] RDX: 00007ff01d8ff080 RSI: 00000000c01064b3 RDI: 0000000000000028
2018-10-16T19:01:36.605283+00:00 WARNING kernel: [   15.728002] RBP: 00007ff01d8ff070 R08: 0000000000000001 R09: 0000000000000000
2018-10-16T19:01:36.605284+00:00 WARNING kernel: [   15.728004] R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000028
2018-10-16T19:01:36.605285+00:00 WARNING kernel: [   15.728007] R13: 000022a20e970000 R14: 00007ff01d8ff080 R15: 00000000c01064b3
2018-10-16T19:01:36.605285+00:00 WARNING kernel: [   15.728011] ---[ end trace 66cd23cb4725d108 ]---
2018-10-16T19:01:36.646060+00:00 WARNING kernel: [   15.768595] WARNING: CPU: 0 PID: 1092 at ../../../../../tmp/portage/sys-kernel/chromeos-kernel-next-4.19-r1/work/chromeos-kernel-next-4.19/drivers/gpu/drm/drm_gem.c:893 drm_gem_object_put+0x1e/0x28
2018-10-16T19:01:36.646072+00:00 WARNING kernel: [   15.768600] Modules linked in: cfg80211 uvcvideo videobuf2_vmalloc videobuf2_memops videobuf2_v4l2 videobuf2_common joydev snd_usb_audio snd_usbmidi_lib snd_hwdep snd_rawmidi hid_multitouch snd_seq_device smsc95xx usbnet mii
2018-10-16T19:01:36.646073+00:00 WARNING kernel: [   15.768617] CPU: 0 PID: 1092 Comm: DrmThread Tainted: G        W         4.19.0-rc8-00841-g61dc60e1aac4 #1
2018-10-16T19:01:36.646074+00:00 WARNING kernel: [   15.768619] Hardware name: GOOGLE Guado, BIOS Google_Guado.6301.108.4 04/01/2015
2018-10-16T19:01:36.646087+00:00 WARNING kernel: [   15.768624] RIP: 0010:drm_gem_object_put+0x1e/0x28
2018-10-16T19:01:36.646088+00:00 WARNING kernel: [   15.768627] Code: 59 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f 1f 44 00 00 55 48 89 e5 48 85 ff 74 18 48 8b 47 08 48 8b 40 68 48 a9 f8 ff ff ff 75 02 <0f> 0b 5d e9 85 fb ff ff 5d c3 0f 1f 44 00 00 55 48 c7 c2 f2 12 f3
2018-10-16T19:01:36.646089+00:00 WARNING kernel: [   15.768630] RSP: 0018:ffffb2c1c0637cd0 EFLAGS: 00010246
2018-10-16T19:01:36.646090+00:00 WARNING kernel: [   15.768634] RAX: 0000000000000000 RBX: ffff924575ee4a00 RCX: 0000000000000000
2018-10-16T19:01:36.646091+00:00 WARNING kernel: [   15.768636] RDX: 0000000100008000 RSI: ffff92457a32b4f0 RDI: ffff924575ee4a00
2018-10-16T19:01:36.646091+00:00 WARNING kernel: [   15.768638] RBP: ffffb2c1c0637cd0 R08: 0000000000000000 R09: 0000000000000000
2018-10-16T19:01:36.646092+00:00 WARNING kernel: [   15.768641] R10: ffff92454be0da78 R11: ffffe8f2052ad1c8 R12: ffff924575dca020
2018-10-16T19:01:36.646093+00:00 WARNING kernel: [   15.768643] R13: ffffb2c1c0637db0 R14: 0000000000000003 R15: 0000000000000030
2018-10-16T19:01:36.646094+00:00 WARNING kernel: [   15.768646] FS:  00007ff01d900700(0000) GS:ffff92457aa00000(0000) knlGS:0000000000000000
2018-10-16T19:01:36.646095+00:00 WARNING kernel: [   15.768648] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
2018-10-16T19:01:36.646096+00:00 WARNING kernel: [   15.768651] CR2: 000022a20f751008 CR3: 0000000174b28001 CR4: 00000000003606f0
2018-10-16T19:01:36.646096+00:00 WARNING kernel: [   15.768653] Call Trace:
2018-10-16T19:01:36.646097+00:00 WARNING kernel: [   15.768660]  udl_gem_mmap+0x72/0x8d
2018-10-16T19:01:36.646098+00:00 WARNING kernel: [   15.768666]  ? drm_mode_create_dumb_ioctl+0xf/0xf
2018-10-16T19:01:36.646099+00:00 WARNING kernel: [   15.768669]  drm_ioctl_kernel+0x8d/0xe4
2018-10-16T19:01:36.646100+00:00 WARNING kernel: [   15.768674]  drm_ioctl+0x294/0x39d
2018-10-16T19:01:36.646101+00:00 WARNING kernel: [   15.768677]  ? drm_mode_create_dumb_ioctl+0xf/0xf
2018-10-16T19:01:36.646102+00:00 WARNING kernel: [   15.768682]  ? __inode_security_revalidate+0x36/0x6c
2018-10-16T19:01:36.646102+00:00 WARNING kernel: [   15.768687]  vfs_ioctl+0x21/0x2f
2018-10-16T19:01:36.646103+00:00 WARNING kernel: [   15.768690]  do_vfs_ioctl+0x4e7/0x50a
2018-10-16T19:01:36.646104+00:00 WARNING kernel: [   15.768695]  ksys_ioctl+0x55/0x75
2018-10-16T19:01:36.646105+00:00 WARNING kernel: [   15.768699]  __x64_sys_ioctl+0x1a/0x1e
2018-10-16T19:01:36.646106+00:00 WARNING kernel: [   15.768702]  do_syscall_64+0x54/0x64
2018-10-16T19:01:36.646107+00:00 WARNING kernel: [   15.768708]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
2018-10-16T19:01:36.646108+00:00 WARNING kernel: [   15.768712] RIP: 0033:0x7ff020980967
2018-10-16T19:01:36.646109+00:00 WARNING kernel: [   15.768715] Code: 8a 66 90 48 8b 05 29 55 2b 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d f9 54 2b 00 f7 d8 64 89 01 48
2018-10-16T19:01:36.646110+00:00 WARNING kernel: [   15.768717] RSP: 002b:00007ff01d8fee38 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
2018-10-16T19:01:36.646111+00:00 WARNING kernel: [   15.768721] RAX: ffffffffffffffda RBX: 000022a20f751d10 RCX: 00007ff020980967
2018-10-16T19:01:36.646112+00:00 WARNING kernel: [   15.768723] RDX: 00007ff01d8fee70 RSI: 00000000c01064b3 RDI: 0000000000000028
2018-10-16T19:01:36.646113+00:00 WARNING kernel: [   15.768725] RBP: 00007ff01d8fee60 R08: 000022a20eb3ee10 R09: 0000000000000003
2018-10-16T19:01:36.646114+00:00 WARNING kernel: [   15.768727] R10: 000022a20f569860 R11: 0000000000000246 R12: 0000000000000028
2018-10-16T19:01:36.646115+00:00 WARNING kernel: [   15.768730] R13: 0000000000000003 R14: 00007ff01d8fee70 R15: 00000000c01064b3
2018-10-16T19:01:36.646115+00:00 WARNING kernel: [   15.768734] ---[ end trace 66cd23cb4725d109 ]---
2018-10-16T19:01:37.792390+00:00 ERR chrome[945]: cras_client: server connect failed: No such file or directory
2018-10-16T19:01:37.921940+00:00 INFO session_manager[873]: [INFO:upstart_signal_emitter.cc(35)] Emitting login-prompt-visible Upstart signal