Bug 82207

My Lenovo ThinkPad T440p is docked to a Lenovo ThinkPad Ultra Dock (40A20135EU, firmware 2.17) with two external monitors attached via DVI / DisplayPort. The current (as of 2014-08-04) DP MST patches are in place.

When logging out from my X session a kernel bug is logged and all displays (internal and external) remain dark:

[  196.902353] kernel BUG at drivers/gpu/drm/i915/i915_gem.c:4111!
[  196.902373] invalid opcode: 0000 [#1] SMP 
[  196.902387] Modules linked in: ctr ccm pci_stub vboxpci(O) vboxnetadp(O) vboxnetflt(O) vboxdrv(O) rfcomm bnep arc4 snd_usb_audio snd_usbmidi_lib nls_iso8859_1 nls_cp437 vfat fat x86_pkg_temp_thermal intel_powerclamp corete
mp cdc_ncm cdc_wdm cdc_acm usbnet mii kvm_intel kvm microcode btusb iwlmvm bluetooth snd_hda_codec_realtek joydev snd_hda_codec_hdmi snd_hda_codec_generic mac80211 serio_raw iwlwifi snd_hda_intel snd_hda_controller snd_hda_co
dec snd_hwdep cfg80211 lpc_ich snd_pcm snd_seq_midi snd_seq_mid
i_event snd_rawmidi thinkpad_acpi nvram snd_seq tpm_tis snd_seq_device snd_timer snd wmi soundcore parport_pc ppdev lp parport hid_generic dm_crypt hid_logitech_dj usbhid hid ghash_clmulni_intel aesni_intel aes_x86_64 psmouse i915 ahci libahci i2c_algo_bit drm_kms_helper e1000e ptp pps_core drm xhci_hcd video
[  196.902653] CPU: 0 PID: 6173 Comm: Xorg Tainted: G        W  O  3.16.0-rc6-tg+ #8
[  196.902676] Hardware name: LENOVO 20ANCTO1WW/20ANCTO1WW, BIOS GLET70WW (2.24 ) 05/21/2014
[  196.902701] task: ffff8803e26ec9b0 ti: ffff8804361a8000 task.ti: ffff8804361a8000
[  196.902724] RIP: 0010:[<ffffffffc0396634>]  [<ffffffffc0396634>] i915_gem_object_ggtt_unpin+0x94/0xa0 [i915]
[  196.902770] RSP: 0018:ffff8804361abc10  EFLAGS: 00010246
[  196.902786] RAX: ffff8804328a5180 RBX: ffff880432ec1500 RCX: ffff880432ea7b28
[  196.902808] RDX: ffff8804328a51e8 RSI: ffff8804328a5180 RDI: 0000000000000000
[  196.902829] RBP: ffff8804361abc18 R08: ffffffffc0424060 R09: 0000000000000000
[  196.902851] R10: 0000000000002ef9 R11: 0000000000000006 R12: ffff8804369f1840
[  196.902872] R13: ffff880437a25060 R14: ffff8804328a5240 R15: ffff8800a5ac7000
[  196.902893] FS:  00007f78690f79c0(0000) GS:ffff88044e200000(0000) knlGS:0000000000000000
[  196.902917] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  196.902935] CR2: 00007f96dd3a2ea4 CR3: 0000000433464000 CR4: 00000000001407f0
[  196.902956] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  196.902977] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  196.902999] Stack:
[  196.903006]  ffff880432ec1500 ffff8804361abc30 ffffffffc0397212 ffff880432ec1500
[  196.903030]  ffff8804361abc48 ffffffffc03c18c9 ffff880437a25000 ffff8804361abca8
[  196.903054]  ffffffffc03cae49 00000100c03c22e1 ffff880432ec1500 ffff88042cddbb80
[  196.903078] Call Trace:
[  196.903097]  [<ffffffffc0397212>] i915_gem_object_unpin_from_display_plane+0x12/0x40 [i915]
[  196.903134]  [<ffffffffc03c18c9>] intel_unpin_fb_obj+0x29/0x40 [i915]
[  196.903165]  [<ffffffffc03cae49>] intel_pipe_set_base+0x199/0x3d0 [i915]
[  196.903195]  [<ffffffffc03cdded>] intel_crtc_set_config+0x9bd/0xe60 [i915]
[  196.903227]  [<ffffffffc02ac284>] drm_mode_set_config_internal+0x64/0xf0 [drm]
[  196.903258]  [<ffffffffc02b0ab9>] drm_mode_setcrtc+0xd9/0x590 [drm]
[  196.903282]  [<ffffffffc02a094c>] drm_ioctl+0x1ec/0x660 [drm]
[  196.903304]  [<ffffffff821ceec8>] do_vfs_ioctl+0x2d8/0x4b0
[  196.903322]  [<ffffffff821beb41>] ? __sb_end_write+0x31/0x60
[  196.903341]  [<ffffffff821bc762>] ? vfs_write+0x172/0x1f0
[  196.903358]  [<ffffffff821cf121>] SyS_ioctl+0x81/0xa0
[  196.903375]  [<ffffffff826b6bd2>] system_call_fastpath+0x16/0x1b
[  196.903394] Code: 8d 57 0f 83 e7 f0 83 e2 0f 09 d7 84 d2 40 88 b8 a8 00 00 00 75 07 80 a3 09 01 00 00 7f 5b 5d c3 0f 1f 80 00 00 00 00 0f 0b 0f 0b <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 
[  196.903480] RIP  [<ffffffffc0396634>] i915_gem_object_ggtt_unpin+0x94/0xa0 [i915]
[  196.903504]  RSP <ffff8804361abc10>

System environment:
-- chipset: QM87
-- system architecture: x86_64
-- xf86-video-intel/xserver/mesa/libdrm version:
   - xf86-video-intel: 2.99.914 (git commit f36b7a4aac86f5874c32d8f516ac1f00a6c8d8b3)
   - xserver: 1.15.1
   - mesa: 10.1.3
   - libdrm: 2.4.52
-- kernel version: 3.16.0-rc6-tg+ (built from drm-next-nightly @ 2014-08-04)
-- Linux distribution: Kubuntu 14.04
-- Machine or mobo model: Lenovo ThinkPad T440p 20AN
-- Display connector: DVI, DisplayPort
3) Reproduce steps.

Log on to X. Work around bug from bug #82153. Log out. The screens remain dark instead of KDM showing up.

Please let me know if you need any further details or if I can help testing any experimental patches.