Ubuntu – 18.04 freezing – how to diagnose / suggestions? (Lenovo x260)

I recently upgraded from 16.04 to 18.04 and have been experiencing hard system freezes, and wondering how to best diagnose these.

Here's what has been happening:

• system completely freezes – display is still present, but no mouse or keyboard response
• no response to ctrl-alt-del, ctrl-alt-backspace
• no response to magic sysrq key (atl-sysrq-reisub – it has been enabled in /etc/sysctl.d/10-magic-sysrq.conf by setting to 1
• inspection of /var/log/syslog after the event shows nothing relevant. sometimes there are a series of null bytes at the time of the crash. kern.log has similar null bytes
• seems to be linked to display changes/glitches, such as docking/undocking, plugging/unplugging HDMI,
• screen is slightly shifted/wrapped, like what happens sometimes temporarily after you plug in a new display and it is detecting.

Details of the machine:

• Lenovo x260:
• Intel(R) Core(TM) i7-6500U CPU @ 2.50GHz
• Intel Corporation HD Graphics 520 (rev 07)
• Bios upgraded: Version: R02ET64W (1.37 ), Release Date: 02/26/2018

Here's what I've tried so far:

• 2 runs of all extended BIOS hardware self tests performed (about 8 hours each), both passed
• tried installing latest drivers from ppa:oibaf/graphics-drivers as per instructions here.

Note that i was experiencing some system hangs under 16.04 which I attributed to the install getting a bit aged, but I didn't investigate beyond casual inspection of syslog (which showed nothing), so I'm not close the the fact that there might be a hardware issues despite the bios self checks passing.

Questions:

• Any suggestions as to what might be cause/fix?
• are there additional log sources I should be looking at to find out what is happening?
• where are X11 logs kept? there's nothing in /var/log/Xorg.log or similar. (Answer: ~/.local/share/xorg/Xorg.0.log)
• is there any additional logging I could/should enable?

lspci output in case this helps:

$ lspci
00:00.0 Host bridge: Intel Corporation Skylake Host Bridge/DRAM Registers (rev 08)
00:02.0 VGA compatible controller: Intel Corporation HD Graphics 520 (rev 07)
00:14.0 USB controller: Intel Corporation Sunrise Point-LP USB 3.0 xHCI Controller (rev 21)
00:14.2 Signal processing controller: Intel Corporation Sunrise Point-LP Thermal subsystem (rev 21)
00:16.0 Communication controller: Intel Corporation Sunrise Point-LP CSME HECI #1 (rev 21)
00:17.0 SATA controller: Intel Corporation Sunrise Point-LP SATA Controller [AHCI mode] (rev 21)
00:1c.0 PCI bridge: Intel Corporation Sunrise Point-LP PCI Express Root Port (rev f1)
00:1c.2 PCI bridge: Intel Corporation Sunrise Point-LP PCI Express Root Port (rev f1)
00:1f.0 ISA bridge: Intel Corporation Sunrise Point-LP LPC Controller (rev 21)
00:1f.2 Memory controller: Intel Corporation Sunrise Point-LP PMC (rev 21)
00:1f.3 Audio device: Intel Corporation Sunrise Point-LP HD Audio (rev 21)
00:1f.4 SMBus: Intel Corporation Sunrise Point-LP SMBus (rev 21)
00:1f.6 Ethernet controller: Intel Corporation Ethernet Connection I219-V (rev 21)
02:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS522A PCI Express Card Reader (rev 01)
05:00.0 Network controller: Intel Corporation Wireless 8260 (rev 3a)

Edit 2:
Happened again. Below is a photo of the screen after it happened. Here's what lead up to it:

• laptop was docked with display blanked
• i undocked the laptop (from this state – didn't unblank the screen with mouse/keyboard input)
• about 15 seconds later i unlocked the screen and did a few things, including opening a new web browser window
• perhaps 30 seconds after that the freeze occurred

Photo of screen when freeze occured

Note – black to white area is has been added to redact screen, and is not an artefact.

Syslog entries from time of crash (16:13)

May 25 16:11:57 redacted gnome-shell[1622]: [AppIndicatorSupport-WARN] Item :1.315/org/ayatana/NotificationItem/dropbox_client_6459 is already registered
May 25 16:11:57 redacted gnome-shell[1622]: [AppIndicatorSupport-WARN] while calling AboutToShow: Gio.IOErrorEnum: Method 'com.canonical.dbusmenu.AboutToShow' returned type '()', but expected '(b)'
May 25 16:11:59 redacted gnome-shell[1622]: STACK_OP_RAISE_ABOVE: sibling window 0x21a12ee not in stack

May 25 16:11:59 redacted gnome-shell[1622]: message repeated 3 times: [ STACK_OP_RAISE_ABOVE: sibling window 0x21a12ee not in stack]
May 25 16:12:04 redacted chromium-browser.desktop[7256]: Created new window in existing browser session.
May 25 16:12:32 redacted wpa_supplicant[971]: wlp4s0: CTRL-EVENT-SIGNAL-CHANGE above=1 signal=-51 noise=9999 txrate=144400
May 25 16:15:43 redacted systemd-modules-load[433]: Inserted module 'lp'
May 25 16:15:43 redacted kernel: [ 0.000000] Linux version 4.15.0-22-generic (buildd@lgw01-amd64-013) (gcc version 7.3.0 (Ubuntu 7.3.0-16ubuntu3)) #24-Ubuntu SMP Wed May 16 12:15:17 UTC 2018 (Ubuntu 4.15.0-22.24-generic 4.15.17)
May 25 16:15:43 redacted kernel: [ 0.000000] Command line: BOOT_IMAGE=/vmlinuz-4.15.0-22-generic root=/dev/mapper/ubuntu–vg-root ro quiet splash vt.handoff=1

Noting the wpa_supplicant log message, I'm wondering whether it might have something to do with the driver for the wifi chipset (Intel 8260)…

Edit 1:

Found the Xorg.log file (~/.local/share/xorg/Xorg.0.log). Possible relevant excerpt:

[    25.113] (II) event7  - ThinkPad Extra Buttons: is tagged by udev as: Keyboard Switch
[    25.113] (II) event7  - ThinkPad Extra Buttons: device is a keyboard
[    25.456] (II) modeset(0): EDID vendor "AUO", prod id 8813
[    25.456] (II) modeset(0): Printing DDC gathered Modelines:
[    25.456] (II) modeset(0): Modeline "1920x1080"x0.0  141.00  1920 1936 1952 2104  1080 1083 1097 1116 -hsync -vsync (67.0 kHz eP)
[ 10304.821] (II) modeset(0): EDID vendor "AUO", prod id 8813
[ 10304.821] (II) modeset(0): Printing DDC gathered Modelines:
[ 10304.821] (II) modeset(0): Modeline "1920x1080"x0.0  141.00  1920 1936 1952 2104  1080 1083 1097 1116 -hsync -vsync (67.0 kHz eP)
[ 20955.619] (II) modeset(0): EDID vendor "AUO", prod id 8813
[ 20955.619] (II) modeset(0): Printing DDC gathered Modelines:
[ 20955.619] (II) modeset(0): Modeline "1920x1080"x0.0  141.00  1920 1936 1952 2104  1080 1083 1097 1116 -hsync -vsync (67.0 kHz eP)
[ 20955.953] (II) modeset(0): Allocate new frame buffer 3840x1080 stride
[ 20956.501] (II) modeset(0): EDID vendor "AUO", prod id 8813
[ 20956.501] (II) modeset(0): Printing DDC gathered Modelines:
[ 20956.501] (II) modeset(0): Modeline "1920x1080"x0.0  141.00  1920 1936 1952 2104  1080 1083 1097 1116 -hsync -vsync (67.0 kHz eP)
[ 30672.277] (II) modeset(0): EDID vendor "DEL", prod id 16498
[ 30672.277] (II) modeset(0): Using hsync ranges from config file
[ 30672.277] (II) modeset(0): Using vrefresh ranges from config file
[ 30672.277] (II) modeset(0): Printing DDC gathered Modelines:
[ 30672.277] (II) modeset(0): Modeline "1920x1080"x0.0  148.50  1920 2008 2052 2200  1080 1084 1089 1125 +hsync +vsync (67.5 kHz eP)
[ 30672.277] (II) modeset(0): Modeline "800x600"x0.0   40.00  800 840 968 1056  600 601 605 628 +hsync +vsync (37.9 kHz e)
[ 30672.277] (II) modeset(0): Modeline "640x480"x0.0   31.50  640 656 720 840  480 481 484 500 -hsync -vsync (37.5 kHz e)
[ 30672.277] (II) modeset(0): Modeline "640x480"x0.0   25.18  640 656 752 800  480 490 492 525 -hsync -vsync (31.5 kHz e)
[ 30672.277] (II) modeset(0): Modeline "720x400"x0.0   28.32  720 738 846 900  400 412 414 449 -hsync +vsync (31.5 kHz e)
[ 30672.277] (II) modeset(0): Modeline "1280x1024"x0.0  135.00  1280 1296 1440 1688  1024 1025 1028 1066 +hsync +vsync (80.0 kHz e)
[ 30672.277] (II) modeset(0): Modeline "1024x768"x0.0   78.75  1024 1040 1136 1312  768 769 772 800 +hsync +vsync (60.0 kHz e)
[ 30672.277] (II) modeset(0): Modeline "1024x768"x0.0   65.00  1024 1048 1184 1344  768 771 777 806 -hsync -vsync (48.4 kHz e)
[ 30672.277] (II) modeset(0): Modeline "800x600"x0.0   49.50  800 816 896 1056  600 601 604 625 +hsync +vsync (46.9 kHz e)
[ 30672.277] (II) modeset(0): Modeline "1152x864"x0.0  108.00  1152 1216 1344 1600  864 865 868 900 +hsync +vsync (67.5 kHz e)
[ 30672.277] (II) modeset(0): Modeline "1280x1024"x0.0  108.00  1280 1328 1440 1688  1024 1025 1028 1066 +hsync +vsync (64.0 kHz e)
[ 30672.277] (II) modeset(0): Modeline "1920x1080"x60.0  172.80  1920 2040 2248 2576  1080 1081 1084 1118 -hsync +vsync (67.1 kHz e)
[ 30682.433] (II) modeset(0): Allocate new frame buffer 1920x2160 stride
[ 30684.350] (II) modeset(0): EDID vendor "DEL", prod id 16498
[ 30684.350] (II) modeset(0): Using hsync ranges from config file
[ 30684.350] (II) modeset(0): Using vrefresh ranges from config file
[ 30684.350] (II) modeset(0): Printing DDC gathered Modelines:
[ 30684.350] (II) modeset(0): Modeline "1920x1080"x0.0  148.50  1920 2008 2052 2200  1080 1084 1089 1125 +hsync +vsync (67.5 kHz eP)
[ 30684.350] (II) modeset(0): Modeline "800x600"x0.0   40.00  800 840 968 1056  600 601 605 628 +hsync +vsync (37.9 kHz e)
[ 30684.350] (II) modeset(0): Modeline "640x480"x0.0   31.50  640 656 720 840  480 481 484 500 -hsync -vsync (37.5 kHz e)
[ 30684.350] (II) modeset(0): Modeline "640x480"x0.0   25.18  640 656 752 800  480 490 492 525 -hsync -vsync (31.5 kHz e)
[ 30684.350] (II) modeset(0): Modeline "720x400"x0.0   28.32  720 738 846 900  400 412 414 449 -hsync +vsync (31.5 kHz e)
[ 30684.350] (II) modeset(0): Modeline "1280x1024"x0.0  135.00  1280 1296 1440 1688  1024 1025 1028 1066 +hsync +vsync (80.0 kHz e)
[ 30684.351] (II) modeset(0): Modeline "1024x768"x0.0   78.75  1024 1040 1136 1312  768 769 772 800 +hsync +vsync (60.0 kHz e)
[ 30684.351] (II) modeset(0): Modeline "1024x768"x0.0   65.00  1024 1048 1184 1344  768 771 777 806 -hsync -vsync (48.4 kHz e)
[ 30684.351] (II) modeset(0): Modeline "800x600"x0.0   49.50  800 816 896 1056  600 601 604 625 +hsync +vsync (46.9 kHz e)
[ 30684.351] (II) modeset(0): Modeline "1152x864"x0.0  108.00  1152 1216 1344 1600  864 865 868 900 +hsync +vsync (67.5 kHz e)
[ 30684.351] (II) modeset(0): Modeline "1280x1024"x0.0  108.00  1280 1328 1440 1688  1024 1025 1028 1066 +hsync +vsync (64.0 kHz e)
[ 30684.351] (II) modeset(0): Modeline "1920x1080"x60.0  172.80  1920 2040 2248 2576  1080 1081 1084 1118 -hsync +vsync (67.1 kHz e)
[ 30685.182] (II) modeset(0): EDID vendor "DEL", prod id 16498
[ 30685.182] (II) modeset(0): Using hsync ranges from config file
[ 30685.182] (II) modeset(0): Using vrefresh ranges from config file
[ 30685.182] (II) modeset(0): Printing DDC gathered Modelines:
[ 30685.182] (II) modeset(0): Modeline "1920x1080"x0.0  148.50  1920 2008 2052 2200  1080 1084 1089 1125 +hsync +vsync (67.5 kHz eP)
[ 30685.182] (II) modeset(0): Modeline "800x600"x0.0   40.00  800 840 968 1056  600 601 605 628 +hsync +vsync (37.9 kHz e)
[ 30685.182] (II) modeset(0): Modeline "640x480"x0.0   31.50  640 656 720 840  480 481 484 500 -hsync -vsync (37.5 kHz e)
[ 30685.182] (II) modeset(0): Modeline "640x480"x0.0   25.18  640 656 752 800  480 490 492 525 -hsync -vsync (31.5 kHz e)
[ 30685.182] (II) modeset(0): Modeline "720x400"x0.0   28.32  720 738 846 900  400 412 414 449 -hsync +vsync (31.5 kHz e)
[ 30685.182] (II) modeset(0): Modeline "1280x1024"x0.0  135.00  1280 1296 1440 1688  1024 1025 1028 1066 +hsync +vsync (80.0 kHz e)
[ 30685.183] (II) modeset(0): Modeline "1024x768"x0.0   78.75  1024 1040 1136 1312  768 769 772 800 +hsync +vsync (60.0 kHz e)
[ 30685.183] (II) modeset(0): Modeline "1024x768"x0.0   65.00  1024 1048 1184 1344  768 771 777 806 -hsync -vsync (48.4 kHz e)
[ 30685.183] (II) modeset(0): Modeline "800x600"x0.0   49.50  800 816 896 1056  600 601 604 625 +hsync +vsync (46.9 kHz e)
[ 30685.183] (II) modeset(0): Modeline "1152x864"x0.0  108.00  1152 1216 1344 1600  864 865 868 900 +hsync +vsync (67.5 kHz e)
[ 30685.183] (II) modeset(0): Modeline "1280x1024"x0.0  108.00  1280 1328 1440 1688  1024 1025 1028 1066 +hsync +vsync (64.0 kHz e)
[ 30685.183] (II) modeset(0): Modeline "1920x1080"x60.0  172.80  1920 2040 2248 2576  1080 1081 1084 1118 -hsync +vsync (67.1 kHz e)
[ 30698.136] (II) modeset(0): EDID vendor "DEL", prod id 16498
[ 30698.136] (II) modeset(0): Using hsync ranges from config file
[ 30698.136] (II) modeset(0): Using vrefresh ranges from config file
[ 30698.136] (II) modeset(0): Printing DDC gathered Modelines:
[ 30698.136] (II) modeset(0): Modeline "1920x1080"x0.0  148.50  1920 2008 2052 2200  1080 1084 1089 1125 +hsync +vsync (67.5 kHz eP)
[ 30698.136] (II) modeset(0): Modeline "800x600"x0.0   40.00  800 840 968 1056  600 601 605 628 +hsync +vsync (37.9 kHz e)
[ 30698.136] (II) modeset(0): Modeline "640x480"x0.0   31.50  640 656 720 840  480 481 484 500 -hsync -vsync (37.5 kHz e)
[ 30698.136] (II) modeset(0): Modeline "640x480"x0.0   25.18  640 656 752 800  480 490 492 525 -hsync -vsync (31.5 kHz e)
[ 30698.136] (II) modeset(0): Modeline "720x400"x0.0   28.32  720 738 846 900  400 412 414 449 -hsync +vsync (31.5 kHz e)
[ 30698.136] (II) modeset(0): Modeline "1280x1024"x0.0  135.00  1280 1296 1440 1688  1024 1025 1028 1066 +hsync +vsync (80.0 kHz e)
[ 30698.136] (II) modeset(0): Modeline "1024x768"x0.0   78.75  1024 1040 1136 1312  768 769 772 800 +hsync +vsync (60.0 kHz e)
[ 30698.136] (II) modeset(0): Modeline "1024x768"x0.0   65.00  1024 1048 1184 1344  768 771 777 806 -hsync -vsync (48.4 kHz e)
[ 30698.136] (II) modeset(0): Modeline "800x600"x0.0   49.50  800 816 896 1056  600 601 604 625 +hsync +vsync (46.9 kHz e)
[ 30698.136] (II) modeset(0): Modeline "1152x864"x0.0  108.00  1152 1216 1344 1600  864 865 868 900 +hsync +vsync (67.5 kHz e)
[ 30698.136] (II) modeset(0): Modeline "1280x1024"x0.0  108.00  1280 1328 1440 1688  1024 1025 1028 1066 +hsync +vsync (64.0 kHz e)
[ 30698.136] (II) modeset(0): Modeline "1920x1080"x60.0  172.80  1920 2040 2248 2576  1080 1081 1084 1118 -hsync +vsync (67.1 kHz e)
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