[lightdm-gtk-greeter] Login doesn't show, uses 100% CPU

[flobe]

lighdm version 1.28.0-1
lightdm-gtk-greeter version 2.0.6-1
kernel: 3.10.18-24

After booting, lightdm seems to start correctly, but lightdm-gtk-greeter uses 100%, never progresses, and never shows a login prompt.
xorg log: https://pastebin.com/JHDncPsK
lightdm log: https://pastebin.com/RyawbYk8
lightdm-gtk-greeter log: https://pastebin.com/NfU1G5qK
lightdm-gtk-greeter strace: https://pastebin.com/PtViu0wc
dmesg: https://pastebin.com/sguizEKh

I can gather more info if required. I'm not sure what triggered the problem, I think it occurred after installing a font and rebooting, but maybe I had also updated packages during that boot.

[TheSaint]

I think that you should try to disable plymouth.

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I don't have any plymouth packages installed, don't see plymouth listed in lightdm.conf or lightdm-gtk-greeter.conf, and don't see any plymouth services (enabled or disabled).

I tried installing plymouth from AUR and the lightdm log went away: https://pastebin.com/kZFJwsAX but lightdm-gtk-greeter is still using 100% CPU and I still have no login prompt.

[TheSaint]

Remove the lightdm service and try to use xinit/startx. Just a test to see what is the main cause.

[flobe]

I $this->bbcode_second_pass_code('', 'systemctl disable lightdm'), rebooted, and then ran $this->bbcode_second_pass_code('', 'lightdm') after non-graphical login (is this equivalent?). Results seemed the same, logs looked the same, failed to open a login prompt. One piece I missed is that both before and now, shutting down blocks for the full 1m30s timeout trying to stop lightdm service.

[nicolasvila]

Hi there.
I'm facing the same issue since a couple of weeks. I'm using ArchLinuxARM on an Odroid XU4.
Everything was OK until an upgrade caused the black screen of death.

I'v tried so many things, including launching the mate-session from the console. It works only if there is no /etc/X11/xorg.conf, which is annoying as I can't have hardware acceleration and the proper graphic driver...

I tried then to install other desktop managers:
gdm: works without xorg.conf
nodm: didn't work but maybe a configuration issue...
lxdm: works perfectly !!!

A clue : lightdm is started with "lightdm" user and so does lightdm-gtk-greeter. lxdm is started as "root". So my guess is that there's maybe some rights issue somewhere. Tried to recompile lightdm and lightdm-gtk-greeter without success...
I will stay with lxdm until I find a better solution to the problem and revert back to lightdm.
Hope it helps

[nicolasvila]

Seems related to a recent systemd upgrade in january. Upgrade to version 240 seems to be the cause:
viewtopic.php?f=60&t=13385
Bug discussion is there:
https://bugzilla.redhat.com/show_bug.cgi?id=1662857
I managed to start lightdm with a modification of the service file.

Add the following line in the [service] section of /lib/systemd/system/lightdm.service

LimitMEMLOCK=4k

[flobe]

$this->bbcode_second_pass_quote('nicolasvila', 'S')eems related to a recent systemd upgrade in january. Upgrade to version 240 seems to be the cause:
viewtopic.php?f=60&t=13385
Bug discussion is there:
https://bugzilla.redhat.com/show_bug.cgi?id=1662857
I managed to start lightdm with a modification of the service file.

Add the following line in the [service] section of /lib/systemd/system/lightdm.service

LimitMEMLOCK=4k