Not sure if this part of dmesg is relevant here.

Oct 27 22:16:29 totbox kernel: BUG: kernel NULL pointer dereference, address: 0000000000000008
Oct 27 22:16:29 totbox kernel: #PF: supervisor read access in kernel mode
Oct 27 22:16:29 totbox kernel: #PF: error_code(0x0000) - not-present page
Oct 27 22:16:29 totbox kernel: PGD 0 P4D 0 
Oct 27 22:16:29 totbox kernel: Oops: 0000 [#1] SMP PTI
Oct 27 22:16:29 totbox kernel: CPU: 1 PID: 1121 Comm: Xorg Not tainted 5.4.0-drm-tip-e2561817d912857cdf7437e73a8fb41256d06edb+ #4
Oct 27 22:16:29 totbox kernel: Hardware name: LENOVO 20HNCTO1WW/20HNCTO1WW, BIOS R0IET58W (1.36 ) 04/19/2019
Oct 27 22:16:29 totbox kernel: RIP: 0010:set_root+0x25/0xb0
Oct 27 22:16:29 totbox kernel: Code: 00 00 00 00 00 0f 1f 44 00 00 55 65 48 8b 04 25 c0 6b 01 00 48 89 e5 41 54 53 48 89 fb 4c 8b a0 d8 06 00 00 f6 47 38 40 74 39 <41> 8b 4c 24 08 f6 c1 01 75 6e 49 8b 54 24 20 49 8b 44 24 18 48 89
Oct 27 22:16:29 totbox kernel: RSP: 0018:ffffaf0ec13ab640 EFLAGS: 00010202
Oct 27 22:16:29 totbox kernel: RAX: ffff982fd95e0000 RBX: ffffaf0ec13ab770 RCX: 0000000000000020
Oct 27 22:16:29 totbox kernel: RDX: ffffffffffffffe0 RSI: 0000000000000000 RDI: ffffaf0ec13ab770
Oct 27 22:16:29 totbox kernel: RBP: ffffaf0ec13ab650 R08: ffff982fef2ae5f0 R09: ffff982fd87dc040
Oct 27 22:16:29 totbox kernel: R10: ffff982fec92a000 R11: ffff9830ec929060 R12: 0000000000000000
Oct 27 22:16:29 totbox kernel: R13: ffff982fec92f020 R14: 0000000000000040 R15: ffff982fd6341800
Oct 27 22:16:29 totbox kernel: FS:  00007fb9fb3c2f00(0000) GS:ffff982fef280000(0000) knlGS:0000000000000000
Oct 27 22:16:29 totbox kernel: CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Oct 27 22:16:29 totbox kernel: CR2: 0000000000000008 CR3: 000000037040a001 CR4: 00000000003606e0
Oct 27 22:16:29 totbox kernel: Call Trace:
Oct 27 22:16:29 totbox kernel:  path_init+0x230/0x310
Oct 27 22:16:29 totbox kernel:  path_openat+0x7e/0x1550
Oct 27 22:16:29 totbox kernel:  ? __wake_up_common_lock+0x8a/0xc0
Oct 27 22:16:29 totbox kernel:  ? ep_poll_callback+0x29a/0x2c0
Oct 27 22:16:29 totbox kernel:  do_filp_open+0x91/0x100
Oct 27 22:16:29 totbox kernel:  ? __wake_up_common_lock+0x8a/0xc0
Oct 27 22:16:29 totbox kernel:  ? string+0x42/0x50
Oct 27 22:16:29 totbox kernel:  ? vsnprintf+0x276/0x4f0
Oct 27 22:16:29 totbox kernel:  file_open_name+0x101/0x150
Oct 27 22:16:29 totbox kernel:  filp_open+0x2c/0x50
Oct 27 22:16:29 totbox kernel:  kernel_read_file_from_path+0x2c/0x70
Oct 27 22:16:29 totbox kernel:  fw_get_filesystem_firmware+0xd3/0x270
Oct 27 22:16:29 totbox kernel:  _request_firmware+0x1ca/0x3f0
Oct 27 22:16:29 totbox kernel:  request_firmware+0x33/0x50
Oct 27 22:16:29 totbox kernel:  edid_load+0x26a/0x330 [drm]
Oct 27 22:16:29 totbox kernel:  drm_load_edid_firmware+0xf1/0x38f [drm]
Oct 27 22:16:29 totbox kernel:  drm_get_override_edid+0x40/0x50 [drm]
Oct 27 22:16:29 totbox kernel:  ? kmalloc_array+0x20/0x20 [drm]
Oct 27 22:16:29 totbox kernel:  drm_do_get_edid+0x23/0x320 [drm]
Oct 27 22:16:29 totbox kernel:  drm_get_edid+0x66/0x380 [drm]
Oct 27 22:16:29 totbox kernel:  drm_dp_mst_get_edid+0x5b/0x70 [drm_kms_helper]
Oct 27 22:16:29 totbox kernel:  intel_dp_mst_get_modes+0x32/0x60 [i915]
Oct 27 22:16:29 totbox kernel:  drm_helper_probe_single_connector_modes+0x173/0x6c0 [drm_kms_helper]
Oct 27 22:16:29 totbox kernel:  drm_client_modeset_probe+0x276/0x10f0 [drm]
Oct 27 22:16:29 totbox kernel:  ? printk+0x58/0x6f
Oct 27 22:16:29 totbox kernel:  ? drm_fb_helper_hotplug_event.part.0+0x66/0xb0 [drm_kms_helper]
Oct 27 22:16:29 totbox kernel:  ? drm_dbg+0x87/0x90 [drm]
Oct 27 22:16:29 totbox kernel:  drm_fb_helper_hotplug_event.part.0+0x7e/0xb0 [drm_kms_helper]
Oct 27 22:16:29 totbox kernel:  drm_fb_helper_restore_fbdev_mode_unlocked+0x75/0xa0 [drm_kms_helper]
Oct 27 22:16:29 totbox kernel:  intel_fbdev_restore_mode+0x30/0x60 [i915]
Oct 27 22:16:29 totbox kernel:  i915_driver_lastclose+0xa/0x10 [i915]
Oct 27 22:16:29 totbox kernel:  drm_lastclose+0x2f/0x50 [drm]
Oct 27 22:16:29 totbox kernel:  drm_release+0xd7/0xe0 [drm]
Oct 27 22:16:29 totbox kernel:  __fput+0xc1/0x250
Oct 27 22:16:29 totbox kernel:  task_work_run+0x87/0xa0
Oct 27 22:16:29 totbox kernel:  do_exit+0x2da/0xb80
Oct 27 22:16:29 totbox kernel:  ? handle_mm_fault+0xc4/0x1f0
Oct 27 22:16:29 totbox kernel:  ? do_user_addr_fault+0x1e4/0x440
Oct 27 22:16:29 totbox kernel:  do_group_exit+0x3a/0xa0
Oct 27 22:16:29 totbox kernel:  __x64_sys_exit_group+0x14/0x20
Oct 27 22:16:29 totbox kernel:  do_syscall_64+0x5b/0x180
Oct 27 22:16:29 totbox kernel:  entry_SYSCALL_64_after_hwframe+0x44/0xa9
Oct 27 22:16:29 totbox kernel: RIP: 0033:0x7fb9fb804e86
Oct 27 22:16:29 totbox kernel: Code: Bad RIP value.
Oct 27 22:16:29 totbox kernel: RSP: 002b:00007ffec711a808 EFLAGS: 00003246 ORIG_RAX: 00000000000000e7
Oct 27 22:16:29 totbox kernel: RAX: ffffffffffffffda RBX: 00007fb9fb8f8740 RCX: 00007fb9fb804e86
Oct 27 22:16:29 totbox kernel: RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
Oct 27 22:16:29 totbox kernel: RBP: 0000000000000000 R08: 00000000000000e7 R09: fffffffffffffc78
Oct 27 22:16:29 totbox kernel: R10: fffffffffffffcc6 R11: 0000000000003246 R12: 00007fb9fb8f8740
Oct 27 22:16:29 totbox kernel: R13: 00000000000000cf R14: 00007fb9fb901408 R15: 0000000000000000

Lakshmi, those errors show up right after I try to shut down, so I believe that is the relevant part.  After that, it hangs, and then you can see me SysRq to get the machine to reboot.

(In reply to Neil Kownacki from comment #0)
> Created attachment 145831 [details]
> dmesg log drm.debug=0xe
> 
> I am experiencing an issue where my system hangs instead of properly
> shutting down when my laptop is docked.  One of my monitors has EDID issues,
> so I have to force an EDID using drm.edid.  I noticed that when I remove the
> parameter, I have no issues shutting down.  This issue occurs on the current
> drm-tip kernel (compiled as of commit
> e2561817d912857cdf7437e73a8fb41256d06edb.)  I believe this may be a
> regression as I do not remember it happening before, but I will need to do
> more digging to find a previous kernel version that works.
> 
> Thinkpad X270 i7-7500U
> UEFI version: R0IET58W (1.36)
> 
> How often: always
> 
> Steps to reproduce:
> 
> -Boot up laptop and login
> -Close lid and put it on the dock
> -Shutdown with the laptop still on the dock

Good to bisection results, bad commit that caused this issue.

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