Bug 2338761 - A notification Xwayland has crashed was sometimes shown when Plasma 6.2.90 started and Xwayland had the error "Cannot write display number to fd 72"
Summary: A notification Xwayland has crashed was sometimes shown when Plasma 6.2.90 st...
Keywords:
Status: CLOSED RAWHIDE
Alias: None
Product: Fedora
Classification: Fedora
Component: kwin
Version: 42
Hardware: Unspecified
OS: Linux
unspecified
medium
Target Milestone: ---
Assignee: Rex Dieter
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard:
: 2343580 (view as bug list)
Depends On:
Blocks: F42FinalBlocker
TreeView+ depends on / blocked
 
Reported: 2025-01-18 18:48 UTC by Matt Fagnani
Modified: 2025-02-27 02:11 UTC (History)
7 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed: 2025-02-27 02:11:21 UTC
Type: ---
Embargoed:


Attachments (Terms of Use)
Journal of Plasma startup with Xwayland has crashed notification and debugging enabled (289.98 KB, text/plain)
2025-02-03 19:54 UTC, Matt Fagnani
no flags Details


Links
System ID Private Priority Status Summary Last Updated
KDE Software Compilation 498837 0 NOR RESOLVED A notification Xwayland has crashed was sometimes shown when Plasma 6.2.90 started even though Xwayland didn't appear to... 2025-02-27 02:06:45 UTC

Description Matt Fagnani 2025-01-18 18:48:18 UTC
I started Plasma 6.2.90 on Wayland using the Fedora Rawhide KDE live images Fedora-KDE-Desktop-Live-Rawhide-20250113.n.0.x86_64.iso and Fedora-KDE-Desktop-Live-Rawhide-20250118.n.0.x86_64.iso in QEMU/KVM VMs in GNOME Boxes and on bare metal. A notification Xwayland has crashed was sometimes shown when Plasma 6.2.90 started even though Xwayland didn't appear to have crashed. I saw this notification about 10/40 times I started Plasma. The notification popup had KWin Window Manager as its title so I'm assigning this to kwin. coredumpctl and the journal didn't show any crashes. ps aux | grep Xwayland showed Xwayland was running. Xwayland might not have started by the time the check for the notification was done at times in a race condition. I didn't see this notification with Plasma 6.2.5 or earlier.


Reproducible: Sometimes

Steps to Reproduce:
1. Download the Fedora Rawhide live image Fedora-KDE-Desktop-Live-Rawhide-20250118.n.0.x86_64.iso from https://koji.fedoraproject.org/koji/buildinfo?buildID=2629884
2. In a Fedora 41 KDE installation, start GNOME Boxes
3. Boot Fedora-KDE-Desktop-Live-Rawhide-20250118.n.0.x86_64.iso in a QEMU/KVM VM in GNOME Boxes with UEFI enabled, 3D acceleration enabled, and 4 GiB RAM.
4. If the notification wasn't shown, log out of Plasma in the VM and log in to Plasma until it does. Alternatively, reboot the VM until the notification appears.

Actual Results:  
A notification Xwayland has crashed was sometimes shown when Plasma 6.2.90 started even though Xwayland didn't appear to have crashed


Expected Results:  
No notification about Xwayland crashing should've been shown.


Linux/KDE Plasma: Fedora Rawhide/42
KDE Plasma Version: 6.2.90
KDE Frameworks Version: 6.10.0
Qt Version: 6.8.1

I reported this problem at https://bugs.kde.org/show_bug.cgi?id=498837

The openQA test KDE-live-iso desktop_notifications_live@uefi failed with Xwayland has crashed in the Notifications applet at https://openqa.fedoraproject.org/tests/3151128#step/desktop_notifications/19

Comment 1 Matt Fagnani 2025-02-03 19:54:19 UTC
Created attachment 2075029 [details]
Journal of Plasma startup with Xwayland has crashed notification and debugging enabled

The Xwayland has crashed notification appears to be from XwaylandLauncher::handleXwaylandFinished https://invent.kde.org/plasma/kwin/-/blob/master/src/xwayland/xwaylandlauncher.cpp#L270

void XwaylandLauncher::handleXwaylandFinished(int exitCode, QProcess::ExitStatus exitStatus)
{
    qCDebug(KWIN_XWL) << "Xwayland process has quit with exit status:" << exitStatus << "exit code:" << exitCode;

#if KWIN_BUILD_NOTIFICATIONS
    KNotification::event(QStringLiteral("xwaylandcrash"), i18n("Xwayland has crashed"));
#endif

In Plasma 6.2.90 in a VM, I put QT_LOGGING_RULES="*.debug=true;qt*.debug=false" in /etc/environment and I restarted Plasma until the Xwayland has crashed notification was shown. There was a fatal server error in Xwayland "Cannot write display number to fd 72", kwin failed to establish the the XCB connection, and Xwayland quit with the code 1.

Jan 21 23:22:47 kwin_wayland_wrapper[9053]: (EE)
Jan 21 23:22:47 kwin_wayland_wrapper[9053]: Fatal server error:
Jan 21 23:22:47 kwin_wayland_wrapper[9053]: (EE) Cannot write display number to fd 72
Jan 21 23:22:47 kwin_wayland_wrapper[9053]: (EE)
Jan 21 23:22:47 kwin_wayland[8992]: kwin_xwl: Failed to establish the XCB connection (error 1)
Jan 21 23:22:47 kwin_wayland[8992]: kwin_xwl: Xwayland process has quit with exit status: QProcess::NormalExit exit code: 1

Xwayland didn't create a core dump. I'm attaching the journal from the Plasma session with the Xwayland has crashed notification.

Comment 2 Adam Williamson 2025-02-03 21:22:31 UTC
*** Bug 2343580 has been marked as a duplicate of this bug. ***

Comment 3 Adam Williamson 2025-02-03 21:23:31 UTC
This is proposed as a Final blocker per "There must be no SELinux denial notifications or crash notifications on boot of or during installation from a release-blocking live image, or at first login after a default install of a release-blocking desktop" - https://fedoraproject.org/wiki/Fedora_42_Final_Release_Criteria#SELinux_and_crash_notifications . With this bug, about 1/3 to 1/4 of the time, you see such a notification when starting KDE.

Comment 4 Matt Fagnani 2025-02-05 23:04:17 UTC
kwin-6.2.91-2.fc42 failed to build with the backport with errors indicating the requested version 6.2.91 didn't match 6.2.90 in the f42 repo https://kojipkgs.fedoraproject.org//work/tasks/3455/128853455/build.log
...
CMake Warning at CMakeLists.txt:154 (find_package):
  Could not find a configuration file for package "Plasma" that is compatible
  with requested version "6.2.91".
  The following configuration files were considered but not accepted:
    /usr/lib64/cmake/Plasma/PlasmaConfig.cmake, version: 6.2.90
    /lib64/cmake/Plasma/PlasmaConfig.cmake, version: 6.2.90
CMake Error at CMakeLists.txt:161 (find_package):
  Could not find a configuration file for package "KDecoration3" that is
  compatible with requested version "6.2.91".
  The following configuration files were considered but not accepted:
    /usr/lib64/cmake/KDecoration3/KDecoration3Config.cmake, version: 6.2.90
    /lib64/cmake/KDecoration3/KDecoration3Config.cmake, version: 6.2.90
-- Configuring incomplete, errors occurred!
error: Bad exit status from /var/tmp/rpm-tmp.JRzD9Y (%build)

This problem might be because the 6.2.91 update was gated by the failed test with Discover crashing and then it was unpushed due to the f42 branching. https://bodhi.fedoraproject.org/updates/FEDORA-2025-c1d22427c2 Building kwin in the side tag f42-build-side-104195 kwin-6.2.91-1.fc42 was built in might avoid those errors. https://koji.fedoraproject.org/koji/buildinfo?buildID=2646632

Comment 5 Adam Williamson 2025-02-05 23:34:14 UTC
Yes, I know. I didn't bother building it on the side tag due to branching. The update has been unpushed now we've branched, and I don't know if we're planning to repush it or create a new one.

Comment 6 Aoife Moloney 2025-02-26 13:24:43 UTC
This bug appears to have been reported against 'rawhide' during the Fedora Linux 42 development cycle.
Changing version to 42.

Comment 7 Matt Fagnani 2025-02-27 02:11:21 UTC
This problem was fixed in kwin 6.3.0 by the patch of Vlad Zahorodnii at https://bugs.kde.org/show_bug.cgi?id=498837#c12


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