Segmentation faults in libQt5 libraries

ZStefan · November 17, 2015, 11:01am

Installed Leap 42.1 on an old laptop. Running KDE. Display Manager is sddm and Window Manager is plasma5.

I encounter many segmentation faults when dealing with windows: moving, resizing or changing settings. The desktop environment freezes, but not the entire computer. Messages in /var/log/messages are like these:

kernel:  1577.597364] systemsettings5[1830]: segfault at 0 ip 00007fe39ce85fea sp 00007ffc6c677f70 error 4 in libQt5Qml.so.5.5.0[7fe39cc8f000+417000]

kernel:  1837.691088] kactivitymanage[1196]: segfault at 7fc0ac591d10 ip 00007fc0ac7d569a sp 00007ffecf5a2c78 error 4 in libQt5Sql.so.5.5.0[7fc0ac7c0000+3f000]

The version of libQtSql5 is 5.5.0.-2.1 and of libQtQuick5 is 5.5.0-1.4. Kernel version is 4.1.12-1-default. Graphic card driver is from Nvidia. The OS is updated daily.

Does anybody know the reason, or a solution?

ZStefan · November 22, 2015, 12:48pm

There is a long discussion of this failure since 2014. It seems that the KDE developers have no clue. Their suggestion is: try this, try that, without end.

But there are likely several errors involved, coming from Qt5, KDE’s parts, graphics driver, graphic card (chip).

https://bugs.kde.org/show_bug.cgi?id=338999

wolfi323 · November 22, 2015, 10:14pm

Hm, I am aware of such crashes of kactivitymanagerd (an update to KF5 is on the way which may make things better though), but they shouldn’t normally crash kwin, in particular not when just moving/resizing windows.

Those QML crashes are graphics driver related most of the time though.
So please post your /var/log/Xorg.0.log to show whether the nvidia driver is actually being used and is working.
And maybe the output of “glxinfo | grep render” too. (you may have to install the package Mesa-demo-x first)

Also, do you use multiple monitors?
That might still be a problem with current Qt5 versions.

You could try to disable Compositing in Configure Desktop->Display and Monitor->Compositor as a workaround, does that help?

ZStefan · November 23, 2015, 7:07am

A senior colleague, who worked with old computers for a long time, seeing Linux or Windows computer being configured or debugged, says: “The number of combinatorial possibilities is mind-boggling. How did you manage to navigate them?”

I went through many of those combinatorial possibilities trying to debug the segmentation fault in KDE. I have tried checking the SHA256 sums, redoing the dd onto memory stick, checking the hard drive and the RAM, re-installing Leap, updating, not updating, limiting the number or repositories, installing and removing Qt4, changing the compositor, various package settings, using Plasma5 and others, changing display manager and windows manager, various windows-related settings, nvidia and nouveau driver, creating new user, and many more.

I observed that most crashes occur when a new pop-up window is going to be created, for example, to expand a menu item.

Currently, I have found that the culprit may be the Plastik windows decoration, perhaps in combination with Qt5 and other settings. Plastik looks very nice and I have used it earlier, but when I switched from it to org.kde.breeze (what a sick name for a good product), the segmentation faults stopped. I haven’t had any since 1/2 day. Earlier, they were ocurring at a rate one per 2 hours when not configuring something and one in 10 minutes when I was doing configuration.

Crashes occur independent of nvidia driver. With nouveau as well.

I use one monitor.

Currently, in a working combination, compositing is enabled and the rendering backend is OpenGL 3.1. Some desktop effects are enabled. Once I see that the crashes indeed stopped, I will come back to disabling-enabling compositor, and report the results.

See continuation in the next post.

ZStefan · November 23, 2015, 7:10am

File /var/log/Xorg.0.log, with some information removed. The full file shows nothing related to crash:


   713.650]
X.Org X Server 1.17.2
Release Date: 2015-06-16
   713.650] X Protocol Version 11, Revision 0
   713.650] Build Operating System: openSUSE SUSE LINUX
   713.650] Current Operating System: Linux hp 4.1.12-1-default #1 SMP PREEMPT Thu Oct 29 06:43:42 
UTC 2015 (e24bad1) x86_64
   713.650] Kernel command line: BOOT_IMAGE=/boot/vmlinuz-4.1.12-1-default 
root=UUID=29acd9ee-d6c3-44ca-8fb0-7a2e050724ee resume=/dev/sda5 splash=verbose 5 showopts
   713.650] Build Date: 25 October 2015  12:36:08PM
   713.650]  
   713.650] Current version of pixman: 0.32.6
   713.650] Markers: (--) probed, (**) from config file, (==) default setting,
    (++) from command line, (!!) notice, (II) informational,
    (WW) warning, (EE) error, (NI) not implemented, (??) unknown.
   713.651] (==) Using config file: "/etc/X11/xorg.conf"
   713.651] (==) Using config directory: "/etc/X11/xorg.conf.d"
   713.651] (==) Using system config directory "/usr/share/X11/xorg.conf.d"
   713.651] (==) ServerLayout "Layout0"
   713.651] (**) |-->Screen "Screen0" (0)
   713.651] (**) |   |-->Monitor "Monitor0"
   713.651] (**) |   |-->Device "Device0"
   713.652] (**) |-->Input Device "Keyboard0"
   713.652] (**) |-->Input Device "Mouse0"
   713.652] (==) Automatically adding devices
   713.652] (==) Automatically enabling devices
   713.652] (==) Automatically adding GPU devices
   713.652] (WW) The directory "/usr/share/fonts/misc/sgi" does not exist.
   713.652]     Entry deleted from font path.
   713.652] (==) ModulePath set to "/usr/lib64/xorg/modules"
   713.652] (WW) Hotplugging is on, devices using drivers 'kbd', 'mouse' or 'vmmouse' will be 
disabled.
   713.652] (WW) Disabling Keyboard0
   713.652] (WW) Disabling Mouse0
   713.652] (II) Loader magic: 0x80dd00
   713.652] (II) Module ABI versions:
   713.652]     X.Org ANSI C Emulation: 0.4
   713.652]     X.Org Video Driver: 19.0
   713.652]     X.Org XInput driver : 21.0
   713.652]     X.Org Server Extension : 9.0
   713.653] (++) using VT number 7

   713.653] (II) systemd-logind: logind integration requires -keeptty and -keeptty was not provided, 
disabling logind integration
   713.653] (II) xfree86: Adding drm device (/dev/dri/card0)
   713.656] (--) PCI:*(0:1:0:0) 10de:0427:103c:30cc rev 161, Mem @ 0xce000000/16777216, 
0xd0000000/268435456, 0xcc000000/33554432, I/O @ 0x00002000/128
   713.656] (II) LoadModule: "glx"
   713.656] (II) Loading /usr/lib64/xorg/modules/extensions/libglx.so
   713.678] (II) Module glx: vendor="NVIDIA Corporation"
   713.678]     compiled for 4.0.2, module version = 1.0.0
   713.678]     Module class: X.Org Server Extension
   713.678] (II) NVIDIA GLX Module  340.93  Wed Aug 19 16:23:51 PDT 2015
   713.678] (II) LoadModule: "nvidia"
   713.678] (II) Loading /usr/lib64/xorg/modules/drivers/nvidia_drv.so
   713.679] (II) Module nvidia: vendor="NVIDIA Corporation"
   713.679]     compiled for 4.0.2, module version = 1.0.0
   713.679]     Module class: X.Org Video Driver
   713.679] (II) NVIDIA dlloader X Driver  340.93  Wed Aug 19 16:01:53 PDT 2015
   713.679] (II) NVIDIA Unified Driver for all Supported NVIDIA GPUs
   713.701] (II) Loading sub module "fb"
   713.701] (II) LoadModule: "fb"
   713.702] (II) Loading /usr/lib64/xorg/modules/libfb.so
   713.702] (II) Module fb: vendor="X.Org Foundation"
   713.702]     compiled for 1.17.2, module version = 1.0.0
   713.702]     ABI class: X.Org ANSI C Emulation, version 0.4
   713.702] (WW) Unresolved symbol: fbGetGCPrivateKey
   713.702] (II) Loading sub module "wfb"
   713.702] (II) LoadModule: "wfb"
   713.702] (II) Loading /usr/lib64/xorg/modules/libwfb.so
   713.702] (II) Module wfb: vendor="X.Org Foundation"
   713.702]     compiled for 1.17.2, module version = 1.0.0
   713.702]     ABI class: X.Org ANSI C Emulation, version 0.4
   713.702] (II) Loading sub module "ramdac"
   713.702] (II) LoadModule: "ramdac"
   713.702] (II) Module "ramdac" already built-in
   713.704] (**) NVIDIA(0): Depth 24, (--) framebuffer bpp 32
   713.704] (==) NVIDIA(0): RGB weight 888
   713.704] (==) NVIDIA(0): Default visual is TrueColor
   713.705] (==) NVIDIA(0): Using gamma correction (1.0, 1.0, 1.0)
   713.705] (**) NVIDIA(0): Enabling 2D acceleration
   714.132] (II) NVIDIA(0): Display (...) does not support NVIDIA 3D
   714.132] (II) NVIDIA(0):     Vision stereo.
   714.132] (II) NVIDIA(GPU-0): Found DRM driver nvidia-drm (20150116)
   714.134] (II) NVIDIA(0): NVIDIA GPU GeForce 8400M GS (G86M) at PCI:1:0:0 (GPU-0)
   714.134] (II) NVIDIA(0): Detected PCI Express Link width: 16X
   714.139] (--) NVIDIA(0): Valid display device(s) on GeForce 8400M GS at PCI:1:0:0

   715.628] (**) Option "config_info" 
"udev:/sys/devices/pci0000:00/0000:00:1d.7/usb2/2-4/2-4:1.0/input/input15/event14"
   715.628] (**) Option "xkb_rules" "evdev"
   715.628] (**) Option "xkb_model" "pc104"
   715.629] (II) config/udev: Adding input device AT Translated Set 2 keyboard (/dev/input/event0)
   715.629] (**) AT Translated Set 2 keyboard: Applying InputClass "evdev keyboard catchall"
   715.629] (**) AT Translated Set 2 keyboard: Applying InputClass "system-keyboard"
   715.629] (**) AT Translated Set 2 keyboard: Applying InputClass "evdev keyboard catchall"
   715.629] (II) Using input driver 'evdev' for 'AT Translated Set 2 keyboard'
   715.629] (**) AT Translated Set 2 keyboard: always reports core events
   715.629] (**) evdev: AT Translated Set 2 keyboard: Device: "/dev/input/event0"
   715.629] (--) evdev: AT Translated Set 2 keyboard: Vendor 0x1 Product 0x1
   715.629] (--) evdev: AT Translated Set 2 keyboard: Found keys
   715.629] (II) evdev: AT Translated Set 2 keyboard: Configuring as keyboard
   715.629] (**) Option "config_info" "udev:/sys/devices/platform/i8042/serio0/input/input0/event0"
   715.629] (II) XINPUT: Adding extended input device "AT Translated Set 2 keyboard" (type: KEYBOARD, 
id 13)
   715.629] (**) Option "xkb_rules" "evdev"
   715.629] (**) Option "xkb_model" "pc104"
   715.629] (**) Option "xkb_layout" "us"
   715.686] (II) config/udev: Adding input device PC Speaker (/dev/input/event9)
   715.686] (II) No input driver specified, ignoring this device.
   715.686] (II) This device may have been added with another device file.
   715.690] (II) config/udev: Adding input device HP WMI hotkeys (/dev/input/event10)
   715.690] (**) HP WMI hotkeys: Applying InputClass "evdev keyboard catchall"
   715.690] (**) HP WMI hotkeys: Applying InputClass "system-keyboard"
   715.690] (**) HP WMI hotkeys: Applying InputClass "evdev keyboard catchall"
   715.690] (II) Using input driver 'evdev' for 'HP WMI hotkeys'
   715.690] (**) HP WMI hotkeys: always reports core events
   715.690] (**) evdev: HP WMI hotkeys: Device: "/dev/input/event10"
   715.690] (--) evdev: HP WMI hotkeys: Vendor 0 Product 0
   715.690] (--) evdev: HP WMI hotkeys: Found keys
   715.690] (II) evdev: HP WMI hotkeys: Configuring as keyboard
   715.690] (**) Option "config_info" "udev:/sys/devices/virtual/input/input11/event10"
   715.690] (**) Option "xkb_rules" "evdev"
   715.690] (**) Option "xkb_model" "pc104"
   715.690] (**) Option "xkb_layout" "us"
   753.348] (II) NVIDIA(0): Setting mode "DFP-0:nvidia-auto-select"
   754.657] (II) NVIDIA(0): ACPI: failed to connect to the ACPI event daemon; the daemon
   754.657] (II) NVIDIA(0):     may not be running or the "AcpidSocketPath" X
   754.657] (II) NVIDIA(0):     configuration option may not be set correctly.  When the
   754.657] (II) NVIDIA(0):     ACPI event daemon is available, the NVIDIA X driver will
   754.657] (II) NVIDIA(0):     try to use it to receive ACPI event notifications.  For
   754.657] (II) NVIDIA(0):     details, please see the "ConnectToAcpid" and
   754.657] (II) NVIDIA(0):     "AcpidSocketPath" X configuration options in Appendix B: X
   754.657] (II) NVIDIA(0):     Config Options in the README.

Output of “glxinfo | grep render”, with some information removed:


direct rendering: Yes
OpenGL renderer string: GeForce .... GS/PCIe/SSE2
    GL_NVX_conditional_render, GL_NVX_gpu_memory_info,
    GL_NV_ES1_1_compatibility, GL_NV_blend_square, GL_NV_conditional_render,
    GL_NV_path_rendering, GL_NV_pixel_data_range, GL_NV_point_sprite,
    GL_NVX_conditional_render, GL_NVX_gpu_memory_info,
    GL_NV_ES1_1_compatibility, GL_NV_blend_square, GL_NV_conditional_render,
    GL_NV_path_rendering, GL_NV_pixel_data_range, GL_NV_point_sprite,
    GL_OES_element_index_uint, GL_OES_fbo_render_mipmap,

ZStefan · November 26, 2015, 2:27pm

On another computer, I encountered the same crash as soon as window decorations were changed to Plastik.

It is interesting that in opensuse 13.2 the theme was called Plastique.

Earlier, it was called Plastik.

Evidently, the name finally got angry and didn’t tolerate any more of its misspellings and changes.

I wish it worked… It was a very good one.

wolfi323 · November 26, 2015, 2:50pm

Plastique is a widget-style built into Qt4, nothing to do with the window decoration. It is imitating KDE3’s Plastik widget style, but is not exactly the same (that’s probably why they called it “Plastique” and not “Plastik”).

KDE’s windeco was always called Plastik and is also called Plastik in KDE4 in 13.2.

Evidently, the name finally got angry and didn’t tolerate any more of its misspellings and changes.

I wish it worked… It was a very good one.

I switched to Plastik here on my 13.2 system a few days ago (Plasma 5.4.3, KF 5.16.0) and haven’t got a single crash yet.
So it’s not only the windeco itself apparently, or there’s a bug in the versions shipped in Leap (but updates for Plasma5 and the Frameworks are pending).

ZStefan · November 26, 2015, 3:29pm

So how do I use Plastik or Plastique in Leap so that this doesn’t cause segmentation faults in Qt5?

ZStefan · November 26, 2015, 3:42pm

So how do I use Plastik or Plastique in Leap so that this doesn’t cause segmentation faults in Qt5?

wolfi323 · November 26, 2015, 4:10pm

How should I know?
It doesn’t crash here (13.2, radeon) in the first place.

I’m only using XRender compositing here though, maybe that’s the difference.
(Kwin doesn’t let me switch to OpenGL 2.1 although my card would support it, because the shader support is too poor…)

I will try tomorrow on an intel system with OpenGL 2.1.

As mentioned I’m using Plasma 5.4.3 and KDE Frameworks 5.16.0 though, which will be released as update for Leap as well soon.
But I also use Qt 5.5.1 from KDE:Qt5 (Leap only has 5.5.0 at the moment). As your crashes are in Qt, that might also be the deciding difference.
I’m not sure what the plans are regarding Qt5 in Leap, i.e. whether an official update to 5.5.1 or even 5.5.2 will be released.
It is possible to install it from KDE:Qt5 on Leap too, but it’s not easy because of the dependencies (you have to break some, and shouldn’t break the wrong ones or your desktop will not start at all any more…)

ZStefan · December 19, 2015, 7:44am

Can somebody knowledgeable look at this log file and tell where the fault is: in Qt5, KDE, Nvidia driver, version mismatch, somewhere else? Maybe a new version of the currently-defective software will arrive soon.

I encounter such crashed from time to time, in different computers. I do updates daily. Other Linux users also encounter them, as Internet search shows. But I couldn’t find a reason.

(Did somebody again use a deleted pointer?)

Application: kdeinit5 (kdeinit5), signal: Segmentation fault
Using host libthread_db library "/lib64/libthread_db.so.1".
[Current thread is 1 (Thread 0x7f1c5cbe6780 (LWP 3642))]

Thread 6 (Thread 0x7f1c45feb700 (LWP 3645)):
#0  0x00007f1c5af85c1d in poll () at /lib64/libc.so.6
#1  0x00007f1c5a484422 in  () at /usr/lib64/libxcb.so.1
#2  0x00007f1c5a48600f in xcb_wait_for_event () at /usr/lib64/libxcb.so.1
#3  0x00007f1c48971c29 in  () at /usr/lib64/libQt5XcbQpa.so.5
#4  0x00007f1c5b2fa55f in  () at /usr/lib64/libQt5Core.so.5
#5  0x00007f1c588f80a4 in start_thread () at /lib64/libpthread.so.0
#6  0x00007f1c5af8e04d in clone () at /lib64/libc.so.6

Thread 5 (Thread 0x7f1c3d3b1700 (LWP 3647)):
#0  0x00007f1c588fe7bc in __lll_lock_wait () at /lib64/libpthread.so.0
#1  0x00007f1c588fa4a4 in _L_lock_986 () at /lib64/libpthread.so.0
#2  0x00007f1c588fa306 in pthread_mutex_lock () at /lib64/libpthread.so.0
#3  0x00007f1c58eb9fcc in  () at /usr/lib64/libGL.so.1
#4  0x00007f1c58ebeb11 in  () at /usr/lib64/libGL.so.1
#5  0x00007f1c58ebefbb in  () at /usr/lib64/libGL.so.1
#6  0x00007f1c56cbbff0 in  () at /usr/lib64/tls/libnvidia-tls.so.352.63
#7  0x00007f1c57c7db60 in  () at /usr/lib64/libglib-2.0.so.0
#8  0x00007f1c57c3c999 in g_main_context_check () at /usr/lib64/libglib-2.0.so.0
#9  0x00007f1c57c3cdf8 in  () at /usr/lib64/libglib-2.0.so.0
#10 0x00007f1c57c3d19a in g_main_loop_run () at /usr/lib64/libglib-2.0.so.0
#11 0x00007f1c3deed426 in  () at /usr/lib64/libgio-2.0.so.0
#12 0x00007f1c57c61f65 in  () at /usr/lib64/libglib-2.0.so.0
#13 0x00007f1c588f80a4 in start_thread () at /lib64/libpthread.so.0
#14 0x00007f1c5af8e04d in clone () at /lib64/libc.so.6

Thread 4 (Thread 0x7f1c347a6700 (LWP 3649)):
#0  0x00007f1c5af85c1d in poll () at /lib64/libc.so.6
#1  0x00007f1c57c3ce64 in  () at /usr/lib64/libglib-2.0.so.0
#2  0x00007f1c57c3cf7c in g_main_context_iteration () at /usr/lib64/libglib-2.0.so.0
#3  0x00007f1c5b52ba5b in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib64/libQt5Core.so.5
#4  0x00007f1c5b4d2a63 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib64/libQt5Core.so.5
#5  0x00007f1c5b2f584a in QThread::exec() () at /usr/lib64/libQt5Core.so.5
#6  0x00007f1c374d3cf7 in KCupsConnection::run() () at /usr/lib64/libkcupslib.so
#7  0x00007f1c5b2fa55f in  () at /usr/lib64/libQt5Core.so.5
#8  0x00007f1c588f80a4 in start_thread () at /lib64/libpthread.so.0
#9  0x00007f1c5af8e04d in clone () at /lib64/libc.so.6

Thread 3 (Thread 0x7f1c2bfff700 (LWP 3650)):
#0  0x00007f1c5af85c1d in poll () at /lib64/libc.so.6
#1  0x00007f1c57c3ce64 in  () at /usr/lib64/libglib-2.0.so.0
#2  0x00007f1c57c3cf7c in g_main_context_iteration () at /usr/lib64/libglib-2.0.so.0
#3  0x00007f1c5b52ba5b in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib64/libQt5Core.so.5
#4  0x00007f1c5b4d2a63 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib64/libQt5Core.so.5
#5  0x00007f1c5b2f584a in QThread::exec() () at /usr/lib64/libQt5Core.so.5
#6  0x00007f1c5b2fa55f in  () at /usr/lib64/libQt5Core.so.5
#7  0x00007f1c588f80a4 in start_thread () at /lib64/libpthread.so.0
#8  0x00007f1c5af8e04d in clone () at /lib64/libc.so.6

Thread 2 (Thread 0x7f1c3287d700 (LWP 3768)):
#0  0x00007ffc5fd46b26 in clock_gettime ()
#1  0x00007f1c5af9ac9d in clock_gettime () at /lib64/libc.so.6
#2  0x00007f1c5b3aab06 in  () at /usr/lib64/libQt5Core.so.5
#3  0x00007f1c5b52a089 in QTimerInfoList::updateCurrentTime() () at /usr/lib64/libQt5Core.so.5
#4  0x00007f1c5b52a615 in QTimerInfoList::timerWait(timespec&) () at /usr/lib64/libQt5Core.so.5
#5  0x00007f1c5b52b82e in  () at /usr/lib64/libQt5Core.so.5
#6  0x00007f1c57c3c4ad in g_main_context_prepare () at /usr/lib64/libglib-2.0.so.0
#7  0x00007f1c57c3cd80 in  () at /usr/lib64/libglib-2.0.so.0
#8  0x00007f1c57c3cf7c in g_main_context_iteration () at /usr/lib64/libglib-2.0.so.0
#9  0x00007f1c5b52ba5b in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib64/libQt5Core.so.5
#10 0x00007f1c5b4d2a63 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib64/libQt5Core.so.5
#11 0x00007f1c5b2f584a in QThread::exec() () at /usr/lib64/libQt5Core.so.5
#12 0x00007f1c5b2fa55f in  () at /usr/lib64/libQt5Core.so.5
#13 0x00007f1c588f80a4 in start_thread () at /lib64/libpthread.so.0
#14 0x00007f1c5af8e04d in clone () at /lib64/libc.so.6

Thread 1 (Thread 0x7f1c5cbe6780 (LWP 3642)):
[KCrash Handler]
#6  0x00007f1c57c75f7c in g_variant_get_child_value () at /usr/lib64/libglib-2.0.so.0
#7  0x00007f1c57c74f94 in g_variant_iter_next () at /usr/lib64/libglib-2.0.so.0
#8  0x00007f1c3396f388 in polkit_details_new_for_gvariant () at /usr/lib64/libpolkit-gobject-1.so.0
#9  0x00007f1c339774eb in polkit_authorization_result_new_for_gvariant () at /usr/lib64/libpolkit-gobject-1.so.0
#10 0x00007f1c3396f65d in  () at /usr/lib64/libpolkit-gobject-1.so.0
#11 0x00007f1c3de84807 in g_simple_async_result_complete () at /usr/lib64/libgio-2.0.so.0
#12 0x00007f1c3deea47d in  () at /usr/lib64/libgio-2.0.so.0
#13 0x00007f1c3de84807 in g_simple_async_result_complete () at /usr/lib64/libgio-2.0.so.0
#14 0x00007f1c3dedf93a in  () at /usr/lib64/libgio-2.0.so.0
#15 0x00007f1c3de84807 in g_simple_async_result_complete () at /usr/lib64/libgio-2.0.so.0
#16 0x00007f1c3de84869 in  () at /usr/lib64/libgio-2.0.so.0
#17 0x00007f1c57c3cb65 in g_main_context_dispatch () at /usr/lib64/libglib-2.0.so.0
#18 0x00007f1c57c3ced8 in  () at /usr/lib64/libglib-2.0.so.0
#19 0x00007f1c57c3d19a in g_main_loop_run () at /usr/lib64/libglib-2.0.so.0
#20 0x00007f1c3397152a in polkit_authority_check_authorization_sync () at /usr/lib64/libpolkit-gobject-1.so.0
#21 0x00007f1c33b8f6ab in PolkitQt1::Authority::checkAuthorizationSync(QString const&, PolkitQt1::Subject const&, QFlags<PolkitQt1::Authority::AuthorizationFlag>) () at /usr/lib64/libpolkit-qt5-core-1.so.1
#22 0x00007f1c33da092d in  () at /usr/lib64/qt5/plugins/kauth/backend/kauth_backend_plugin.so
#23 0x00007f1c33da1bbe in  () at /usr/lib64/qt5/plugins/kauth/backend/kauth_backend_plugin.so
#24 0x00007f1c33da2535 in  () at /usr/lib64/qt5/plugins/kauth/backend/kauth_backend_plugin.so
#25 0x00007f1c5b504996 in QMetaObject::activate(QObject*, int, int, void**) () at /usr/lib64/libQt5Core.so.5
#26 0x00007f1c5738e247 in  () at /usr/lib64/libgobject-2.0.so.0
#27 0x00007f1c573a6418 in g_signal_emit_valist () at /usr/lib64/libgobject-2.0.so.0
#28 0x00007f1c573a7592 in g_signal_emit_by_name () at /usr/lib64/libgobject-2.0.so.0
#29 0x00007f1c539ab05d in  () at /usr/lib64/libffi.so.4
#30 0x00007f1c539aa781 in  () at /usr/lib64/libffi.so.4
#31 0x00007f1c5738e858 in g_cclosure_marshal_generic () at /usr/lib64/libgobject-2.0.so.0
#32 0x00007f1c5738e018 in g_closure_invoke () at /usr/lib64/libgobject-2.0.so.0
#33 0x00007f1c5739f22d in  () at /usr/lib64/libgobject-2.0.so.0
#34 0x00007f1c573a6da8 in g_signal_emit_valist () at /usr/lib64/libgobject-2.0.so.0
#35 0x00007f1c573a7062 in g_signal_emit () at /usr/lib64/libgobject-2.0.so.0
#36 0x00007f1c3dee98fc in  () at /usr/lib64/libgio-2.0.so.0
#37 0x00007f1c3ded9ae5 in  () at /usr/lib64/libgio-2.0.so.0
#38 0x00007f1c57c3cb65 in g_main_context_dispatch () at /usr/lib64/libglib-2.0.so.0
#39 0x00007f1c57c3ced8 in  () at /usr/lib64/libglib-2.0.so.0
#40 0x00007f1c57c3cf7c in g_main_context_iteration () at /usr/lib64/libglib-2.0.so.0
#41 0x00007f1c5b52ba3c in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib64/libQt5Core.so.5
#42 0x00007f1c5b4d2a63 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib64/libQt5Core.so.5
#43 0x00007f1c5b4da5d6 in QCoreApplication::exec() () at /usr/lib64/libQt5Core.so.5
#44 0x00007f1c48e285b4 in kdemain () at /usr/lib64/libkdeinit5_kded5.so
#45 0x0000000000408cc3 in  ()
#46 0x0000000000405d46 in main ()

wolfi323 · December 19, 2015, 2:05pm

This crash is in glib.
Might be caused by the nvidia driver, wouldn’t be the first time that it causes strange crashes/hangs in glib because of bugs in the signal handling.

More details about your backtrace:
Some kded module requests root permissions via kauth.
kauth in turn uses polkit to verify if this is allowed (and ask for the root password if necessary), which then crashes.

So to fix those crashes, find out which kded module is causing this, by disabling them one by one.
I would speculate it is the backlight control that requires root permissions (which would again point to an nvidia driver related problem), so try to disable the powermanagement module first (in Configure Desktop->Startup and Shutdown->Background Services) and see if it “fixes” the crashes.