Any chance to provide a screenshot? Which graphics driver is this about?

Created attachment 321250 [details]
example of the issue after logging in

the machine has integrated intel graphics with current drivers as in current Arch.

This is likely a mesa a bug. Which mesa version is this? When did it start happening? Can you try an older mesa version?

Mesa is on 11.1.2-1 here, and I don't think I can roll back easily right now

i forgot to add: the behaviour started to occur on the 5. 2.

And what packages got updated on that day?

nothing that would obviously suggest itself as a source for the problem:


[2016-02-04 09:33] [PACMAN] Running 'pacman -Syu'
[2016-02-04 09:33] [PACMAN] synchronizing package lists
[2016-02-04 09:33] [PACMAN] starting full system upgrade
[2016-02-04 09:33] [ALPM] transaction started
[2016-02-04 09:33] [ALPM] upgraded libbsd (0.8.1-1 -> 0.8.2-1)
[2016-02-04 09:33] [ALPM] upgraded pixman (0.32.8-1 -> 0.34.0-1)
[2016-02-04 09:33] [ALPM] upgraded plank (0.10.1-1 -> 0.10.1-2)
[2016-02-04 09:33] [ALPM] upgraded vlc (2.2.1-12 -> 2.2.1-13)
[2016-02-04 09:33] [ALPM] transaction completed
[2016-02-04 17:17] [PACMAN] Running 'pacman -Syu'
[2016-02-04 17:17] [PACMAN] synchronizing package lists
[2016-02-04 17:17] [PACMAN] starting full system upgrade
[2016-02-04 17:17] [ALPM] transaction started
[2016-02-04 17:17] [ALPM] upgraded gedit (3.18.2-1 -> 3.18.3-1)
[2016-02-04 17:17] [ALPM] upgraded giflib (5.1.1-1 -> 5.1.2-1)
[2016-02-04 17:17] [ALPM] upgraded goffice (0.10.24-1 -> 0.10.26-1)
[2016-02-04 17:17] [ALPM] upgraded gnumeric (1.12.24-1 -> 1.12.26-1)
[2016-02-04 17:17] [ALPM] upgraded libwacom (0.17-1 -> 0.18-1)
[2016-02-04 17:17] [ALPM] transaction completed
[2016-02-04 23:43] [PACMAN] Running 'pacman -Syu'
[2016-02-04 23:43] [PACMAN] synchronizing package lists
[2016-02-04 23:43] [PACMAN] starting full system upgrade
[2016-02-04 23:44] [ALPM] transaction started
[2016-02-04 23:44] [ALPM] upgraded libcap (2.24-2 -> 2.25-1)
[2016-02-04 23:44] [ALPM] upgraded bind-tools (9.10.3.P3-1 -> 9.10.3.P3-2)
[2016-02-04 23:44] [ALPM] upgraded v4l-utils (1.6.3-3 -> 1.10.0-1)
[2016-02-04 23:44] [ALPM] transaction completed

there was a mesa upgrade later (on the 11.), but that didn't have any impact, the last one before that was on 15.1.

however, there was a point release kernel update on the 3.2. (4.4.1-1 -> 4.4.1-2).

shot in the dark but: try going back to pixman 0.32

do you have an idea where I could get that? it is not in my package cache (i have the files 
/usr/lib/libpixman-1.so
/usr/lib/libpixman-1.so.0
/usr/lib/libpixman-1.so.0.32.8
 though).

(In reply to charlesaymard from comment #11)
> do you have an idea where I could get that? it is not in my package cache (i

You'll have to ask an Arch person or check their docs.

> have the files 
> /usr/lib/libpixman-1.so
> /usr/lib/libpixman-1.so.0
> /usr/lib/libpixman-1.so.0.32.8
>  though).

I suggested pixman 0.32 because

> [2016-02-04 09:33] [ALPM] upgraded pixman (0.32.8-1 -> 0.34.0-1)

so if you have those files on disk that's surprising. You'll have to find that out by yourself though.

i found a copy of the old pixman version and installed it, I'll see what happens (or not).

the issue just occured again with the older pixman version

Can you try older mesa and/or kernel ?

not really.. I would rather get an idea for what might be going on/how to find diagnostic info

fwiw the issue has not reoccurred in a while, with no specific action being taken. also, switching the dm to lightdm hadn't done anything.

on 3.20, this still happens some times (rarely), without any apparent regularity

*** This bug has been marked as a duplicate of bug 766146 ***