https://bugs.kde.org/show_bug.cgi?id=509676
Bug ID: 509676
Summary: kwin crashes when monitors disconnected through dock
Classification: Plasma
Product: kwin
Version First 6.3.4
Reported In:
Platform: Ubuntu
OS: Linux
Status: REPORTED
Severity: crash
Priority: NOR
Component: multi-screen
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
Created attachment 185093
--> https://bugs.kde.org/attachment.cgi?id=185093&action=edit
Output of journalctl --user --since "30 minutes ago" | grep -E
"(kwin|wayland|EE)" during undock
Note: Running Plasma 6.4.3 from Kubuntu Beta PPA.
Debug symbols only available for 6.3.4, tried to take a trace with gdb, but I
get `(No debugging symbols found in kwin_wayland)`
SUMMARY
KWin Wayland crashes when disconnecting any DisplayPort monitor on Intel
TigerLake-LP GT2 with kernel 6.14.0.
KWin crashes when disconnecting display from dock, or disconnecting dock from
laptop.
Was previously running Kubuntu 24.04.3, which was working fine. (Plasma 5.27 I
believe), so I would imagine this was introduced in Plasma 6 when I upgraded to
Kubuntu 25.04.
STEPS TO REPRODUCE
1. Unplug a monitor (DisplayPort or HDMI) from HP USB-C or Thunderbolt docking
station (have not tried other dock vendors)
OBSERVED RESULT
KWin crashes, KDE apps are restarted, but all other apps remain closed.
EXPECTED RESULT
Screen layout changes and app remains open
SOFTWARE/OS VERSIONS
Operating System: Kubuntu 25.04
KDE Plasma Version: 6.4.3 (from Kubuntu Beta PPA), but the issue was present on
the Plasma version included in 25.04
KDE Frameworks Version: 6.14.0
Qt Version: 6.8.3
Kernel Version: 6.14.0-29-generic (64-bit)
Graphics Platform: Wayland
Processors: 8 × 11th Gen Intel® Core™ i5-1135G7 @ 2.40GHz
Memory: 64 GiB of RAM (62.5 GiB usable)
Graphics Processor: Intel® Iris® Xe Graphics (Intel TigerLake-LP GT2 Iris Xe
Graphics (device ID 9a49))
Manufacturer: HP
Product Name: HP ProBook 650 G8 Notebook PC
System Version: SBKPF
ADDITIONAL INFORMATION
Issue does not occur with a monitor attached directly to the laptop HDMI port.
Logs attached are of an undock event at 2025-09-19 08:00.
journalctl.log is output of `journalctl --user --since "30 minutes ago" | grep
-E "(kwin|wayland|EE)"`
`dmesg -w` shows:
1426 │ [ 75.352419] thunderbolt 0-1: device disconnected
1427 │ [ 75.367135] pcieport 0000:00:07.0: pciehp: Slot(0): Link Down
1428 │ [ 75.367190] pcieport 0000:00:07.0: pciehp: Slot(0): Card not
present
1429 │ [ 75.367255] pcieport 0000:02:04.0: Unable to change power state
from D3hot to D0, device inaccessible
1430 │ [ 75.370300] pcieport 0000:02:04.0: Runtime PM usage count
underflow!
1431 │ [ 75.370540] xhci_hcd 0000:03:00.0: remove, state 1
1432 │ [ 75.370612] usb usb6: USB disconnect, device number 1
1433 │ [ 75.370634] usb 6-1: USB disconnect, device number 2
1434 │ [ 75.370653] usb 6-1.3: USB disconnect, device number 3
1435 │ [ 75.370672] r8152-cfgselector 6-1.3.3: USB disconnect, device
number 4
1436 │ [ 75.371316] xhci_hcd 0000:03:00.0: xHCI host controller not
responding, assume dead
1437 │ [ 75.524654] xhci_hcd 0000:03:00.0: USB bus 6 deregistered
1438 │ [ 75.524708] xhci_hcd 0000:03:00.0: remove, state 1
1439 │ [ 75.524726] usb usb5: USB disconnect, device number 1
1440 │ [ 75.524732] usb 5-1: USB disconnect, device number 2
1441 │ [ 75.524737] usb 5-1.3: USB disconnect, device number 3
1442 │ [ 75.524741] usb 5-1.3.5: USB disconnect, device number 6
1443 │ [ 75.753192] usb 5-1.3.7: USB disconnect, device number 7
1444 │ [ 75.859260] kwin_wayland[4412]: segfault at 3c0 ip 000071a385944c6b
sp 00007ffec4f3d330 error 4 in libkwin.so.6.4.3[544c6b,71a3855ae000+551000]
likely on CPU 0 (core 0, socket 0)
1445 │ [ 75.859286] Code: 6b 60 e8 a8 2a cc ff 48 8d 7b 68 b9 62 00 00 00
48 c7 45 a8 00 00 00 00 48 89 c6 48 8d 05 bd 00 00 00 48 c7 45 b8 00 00 00 00
<f3> 48 a5 48 89 45 a0 48 8d 05 c7 ce cb ff bf 20 00 0
│ 0 00 48 89 45
Steps to Reproduce
1. Connect external monitor via Thunderbolt dock (DisplayPort)
2. Ensure monitor is working and detected properly
3. Physically disconnect the monitor cable from the dock
4. KWin immediately crashes
Expected Behavior
Monitor should disconnect cleanly without crashing the compositor. Applications
should remain running.
Actual Behavior
- KWin crashes immediately upon monitor disconnect
- All Wayland-native applications crash (Firefox, Chrome, Teams, DataGrip,
OnlyOffice)
- KDE applications survive
- System automatically restarts KWin after crash
Hardware Detection
```
[ 10.440714] i915 0000:00:02.0: [drm] Found tigerlake/uy (device ID 9a49)
integrated display version 12.00 stepping C0
[ 10.507838] i915 0000:00:02.0: [drm] Finished loading DMC firmware
i915/tgl_dmc_ver2_12.bin (v2.12)
[ 10.575607] [drm] Initialized i915 1.6.0 for 0000:00:02.0 on minor 1
```
Applied Kernel Parameters
Tried adding the following with no change in outcome. Logs are from system
WITHOUT these parameters present.
```
i915.enable_psr=0 i915.enable_dc=0 intel_idle.max_cstate=2
processor.max_cstate=2
```
KWin Environment Variables Tested
Tried adding the following, without any change in outcome. Logs are from system
WITHOUT these added.
```
KWIN_DRM_NO_AMS=1
KWIN_FORCE_SW_CURSOR=1
KWIN_DRM_USE_ATOMIC=0
QT_LOGGING_RULES="kwin_*.debug=true"
```
Reproducibility: 100% - crash occurs on every single monitor disconnect
Scope: Affects both single monitor disconnects from dock and full dock
undocking, but not directly attached monitor being disconnected from laptop.
Attempted Solutions
Intel driver parameters: Applied standard TigerLake stability parameters - no
effect
KWin configuration: Disabled atomic mode setting, various environment variables
- no effect
Plasma upgrade: Upgraded from 6.3.4 to 6.4.3 - issue persists
Hardware testing: Issue occurs with both USB-C and Thunderbolt docks and
monitors.
Additional Context
- Issue did not exist on Ubuntu 24.04.3 with Plasma 5.27.11.
I first noticed it after upgrading to 25.04 Plasma 6.3.4 (same kernel version).
- All monitors work correctly when connected, disconnecting one via undocking,
or by disconnecting a monitor from the dock causes the crash
- KDE applications survive crash better than non-KDE applications
- System otherwise stable, no other graphics issues
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