Re: kscreenlocker kicks out user sessions
On 07/11/2023 21:53, Max Nikulin wrote:
- Plasma X11 login
- Activate screen locker
- Switch to another user
- Select the same user in the desktop manager.
I have tried SDDM and LightDM with lightdm-gtk-greeter.
- Type password
In my case the created earlier session is terminated and desktop manager
screen appears again.
This recipe to get crash works rater reliable inside a VM, but not on
the host.
The following line appears in logs:
kscreenlocker_greet[2446]: pam_unix(kde:auth): authentication failure;
logname= uid=1001 euid=1001 tty= ruser= rhost= user=test
This message appears even in cases when the session is successfully
unlocked. So it is a misleading error.
kscreenlocker significantly increases probability of session
termination, but with more repetitions it may be experienced even with
fluxbox.
Actually I have seen 2 scenarios of crash as they appear in Xorg logs.
1. Perhaps something involved with polkit and a race with granting
permissions to current user:
[ 4721.881] (WW) qxl(0): drmSetMaster failed: Device or resource busy
[ 4721.881] (EE) qxl(0): failed to set mode: Permission denied(EE)
Fatal server error:
[ 4721.881] (EE) EnterVT failed for screen 0
[ 4721.881] (EE)
2. Segfault
[ 3444.301] (EE) Backtrace:
[ 3444.301] (EE) 0: /usr/lib/xorg/Xorg (OsLookupColor+0x139)
[0x55fc14832d29]
[ 3444.302] (EE) 1: /lib/x86_64-linux-gnu/libc.so.6 (__sigaction+0x40)
[0x7f983dc5afd0]
[ 3444.302] (EE) unw_get_proc_name failed: no unwind info found [-10]
[ 3444.302] (EE) 2: /usr/lib/xorg/modules/drivers/qxl_drv.so (?+0x0)
[0x7f983d65e0e7]
[ 3444.302] (EE) unw_get_proc_name failed: no unwind info found [-10]
[ 3444.302] (EE) 3: /usr/lib/xorg/modules/drivers/qxl_drv.so (?+0x0)
[0x7f983d65f1a7]
[ 3444.302] (EE) 4: /usr/lib/xorg/Xorg (xf86CrtcSetModeTransform+0x27f)
[0x55fc1473561f]
[ 3444.302] (EE) 5: /usr/lib/xorg/Xorg (xf86SetDesiredModes+0xec)
[0x55fc14735b4c]
[ 3444.302] (EE) unw_get_proc_name failed: no unwind info found [-10]
[ 3444.303] (EE) 6: /usr/lib/xorg/modules/drivers/qxl_drv.so (?+0x0)
[0x7f983d65ddc4]
[ 3444.303] (EE) 7: /usr/lib/xorg/Xorg (xf86CVTMode+0x23ae)
[0x55fc1473c52e]
[ 3444.303] (EE) 8: /usr/lib/xorg/Xorg (xf86VTEnter+0x81) [0x55fc146fee31]
[ 3444.303] (EE) 9: /usr/lib/xorg/Xorg (WakeupHandler+0xb3)
[0x55fc146c4243]
[ 3444.303] (EE) 10: /usr/lib/xorg/Xorg (WaitForSomething+0x198)
[0x55fc1482c6e8]
[ 3444.303] (EE) 11: /usr/lib/xorg/Xorg (SendErrorToClient+0x113)
[0x55fc146bf473]
[ 3444.303] (EE) 12: /usr/lib/xorg/Xorg (InitFonts+0x3bc) [0x55fc146c36cc]
[ 3444.303] (EE) 13: /lib/x86_64-linux-gnu/libc.so.6
(__libc_init_first+0x8a) [0x7f983dc461ca]
[ 3444.304] (EE) 14: /lib/x86_64-linux-gnu/libc.so.6
(__libc_start_main+0x85) [0x7f983dc46285]
[ 3444.304] (EE) 15: /usr/lib/xorg/Xorg (_start+0x21) [0x55fc146acb71]
[ 3444.304] (EE)
[ 3444.304] (EE) Segmentation fault at address 0x55f94a6d9e35
[ 3444.304] (EE)
Fatal server error:
[ 3444.304] (EE) Caught signal 11 (Segmentation fault). Server aborting
I have seen some bugs with OsLookupColor, but "xf86CrtcSetModeTransform"
does not appear in search results.
So likely it is something related with (deprecated?) QXL video driver.
kscreenlocker just makes the issue more apparent.
I am less sure now that I have really seen the bug on the host.
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