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Details

Type: Bug
Resolution: Done
Priority: P1: Critical
Fix Version/s: 5.15.3, 5.15.7, 6.1.2, 6.2.0 Alpha
Affects Version/s: 5.15.2, 6.0.0
Component/s: QPA: Wayland
Labels:
- Reported_by_support_standard

Platform/s:

Linux/Wayland
Commits:
b19b0fbaf775e8b8eda1e03c265a5393d618c6c0 (qt/qtwayland/dev) a3ee3b1ac6752cb1e1bf86f8ef972f7d410e1d50 (qt/tqtc-qtwayland/5.15) c0ef4aa9529453197245f2db36df1d6b064e8532 (qt/qtwayland/6.1)

Description

Hi,

When running the following snippet, the program will segfault as soon as the instantiated window is hidden by the timer:

import QtQuick 2.15
import QtQuick.Window 2.2

Window {
    component TestPopup: Window {
        id: win
        visibility: Window.Windowed
        width: 150
        height: 150
        Rectangle {
            anchors.centerIn: parent
            width: 100
            height: 100
            color: "red"
            RotationAnimation on rotation {
                loops: Animation.Infinite
                from: 0
                to: 360
            }
        }
        Timer {
            running: true
            repeat: true
            interval: 500 + Math.random() * 500
            onTriggered: {
                if (win.visibility != Window.Hidden)
                    win.visibility = Window.Hidden;
                else
                    win.visibility = Window.Windowed;
            }
        }
    }
    TestPopup { color: "blue" }
}

I'm running the snippet with the following command:

QT_QPA_PLATFORM=wayland-egl qml snippet.qml

AFAIK this was working fine in Qt 5.9. What we see is that the platform window is destroyed after a call to setVisible(false), which triggers the destruction of the wl_egl_window and wl_surface. But the scenegraph thread is still using the window for rendering (ie calling swapBuffers), so the process crashes. I can reproduce this on both GNOME/wayland with up to date mesa drivers and also on embedded devices with proprietary drivers.

I can reproduce the issue with both Qt 5.15 and Qt 6.0.

Here's the stack trace with Qt6:

0x00007ffff1534db0 in QtWayland::wl_surface::damage_buffer(int, int, int, int) () from /home/rawoul/Work/Qt/6.0.1/gcc_64/plugins/platforms/../../lib/libQt6WaylandClient.so.6
(gdb) bt
#0  0x00007ffff1534db0 in QtWayland::wl_surface::damage_buffer(int, int, int, int) () at /home/rawoul/Work/Qt/6.0.1/gcc_64/plugins/platforms/../../lib/libQt6WaylandClient.so.6
#1  0x00007ffff1503a91 in QtWaylandClient::QWaylandAbstractDecoration::contentImage() () at /home/rawoul/Work/Qt/6.0.1/gcc_64/plugins/platforms/../../lib/libQt6WaylandClient.so.6
#2  0x00007ffff1a21ad1 in  () at /home/rawoul/Work/Qt/6.0.1/gcc_64/plugins/platforms/libqwayland-egl.so
#3  0x00007ffff6546bff in QOpenGLContext::swapBuffers(QSurface*) () at /home/rawoul/Work/Qt/6.0.1/gcc_64/bin/../lib/libQt6Gui.so.6
#4  0x00007ffff656a451 in  () at /home/rawoul/Work/Qt/6.0.1/gcc_64/bin/../lib/libQt6Gui.so.6
#5  0x00007ffff640eedd in QRhi::endFrame(QRhiSwapChain*, QFlags<QRhi::EndFrameFlag>) () at /home/rawoul/Work/Qt/6.0.1/gcc_64/bin/../lib/libQt6Gui.so.6
#6  0x00007fffc615addb in  () at /home/rawoul/Work/Qt/6.0.1/gcc_64/qml/QtQuick/../../lib/libQt6Quick.so.6
#7  0x00007fffc615c5f7 in  () at /home/rawoul/Work/Qt/6.0.1/gcc_64/qml/QtQuick/../../lib/libQt6Quick.so.6
#8  0x00007ffff5addec6 in  () at /home/rawoul/Work/Qt/6.0.1/gcc_64/bin/../lib/libQt6Core.so.6
#9  0x00007ffff5448590 in start_thread (arg=0x7fffc52db640) at pthread_create.c:463
#10 0x00007ffff536e223 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95