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Bug 749705

Summary: kde-plasma/plasma-workspace-5.19.5-r2: plasmashell crashes in libQt5Qml
Product: Gentoo Linux Reporter: Tom <sl.tom>
Component: Current packagesAssignee: Gentoo KDE team <kde>
Status: RESOLVED WORKSFORME    
Severity: normal CC: jstein
Priority: Normal    
Version: unspecified   
Hardware: x86   
OS: Linux   
Whiteboard:
Package list:
Runtime testing required: ---
Attachments: requested information

Description Tom 2020-10-17 12:57:51 UTC
Created attachment 666194 [details]
requested information

After upgrading to plasma-meta-5.19.5 kde won't run - after initializing 80% it hangs and, after some time, shows a black screen with only xosview running. I'm able to move the mouse, but nothing else happens.

/var/log/syslog shows plasmashell crashing inside libqt5qml:

Oct 17 14:07:24 laptop kernel: [10179.134284] plasmashell[16998]: segfault at 14 ip b71e186a sp bfe2cce0 error 4 in libQt5Qml.so.5.14.2[b715f000+2e1000]
Oct 17 14:07:24 laptop kernel: [10179.134291] Code: 74 24 28 e8 08 f8 f7 ff 83 c4 10 e9 79 ff ff ff 57 56 53 8b 4c 24 14 e8 d4 3c f8 ff 81 c3 a4 77 3d 00 8b 7c 24 10 85 c9 74 56 <8b> 71 04 31 c0 ba 00 80 02 00 85 f6 74 3c f6 46 10 0c 75 36 8b 76

Therefore I've recompiled qtdeclarative-5.14.2-r4, which holds the above library, but without success.

emerge -pqv of the relevant packages:

[ebuild   R   ] kde-plasma/plasma-meta-5.19.5  USE="browser-integration desktop-portal display-manager elogind handbook networkmanager sddm wallpapers -bluetooth -crypt -discover -grub -gtk -kwallet -legacy-systray -plymouth -pulseaudio -qrcode -sdk -systemd -thunderbolt" 
[ebuild   R   ] kde-plasma/plasma-workspace-5.19.5-r2  USE="handbook -appstream -calendar -debug -geolocation -gps -qalculate -qrcode -semantic-desktop -systemd -telemetry -test" 
[ebuild   R   ] kde-frameworks/plasma-5.74.0-r1  USE="X -debug -doc -gles2-only -test -wayland" 
[ebuild   R   ] dev-qt/qtdeclarative-5.14.2-r4  USE="jit widgets -debug -gles2-only -localstorage -test -vulkan"

The attached tar additionally holds this information:
- output of emerge --info
- small extract of /var/log/syslog up to the crash
- dot.Xerrors - from starting up to killing xinit

CU Tom
Comment 1 Andreas Sturmlechner gentoo-dev 2020-10-17 13:53:53 UTC
Please try with a clean testuser.
Comment 2 Tom 2020-10-17 15:15:09 UTC
Starting kde plasma as an ordinary user works, although slower.

OTOH running plasma as su worked for many years - and I am aware of the possible risk. ;)

Meanwhile searching the net (using xfce4) it looks like qtqml v5.14 might be the problem when using plasma v5.19 - several users using binary distributions had the same problem with a crashing plasmashell...
I've read about qtqml v5.15.2 should have fixed the segfault?

Do you think my problem could be solved marking all qt* v5.15 packages using the ~x86 flag?

CU Tom
Comment 3 Andreas Sturmlechner gentoo-dev 2020-10-17 15:45:20 UTC
(In reply to Tom from comment #2)
> Starting kde plasma as an ordinary user works, although slower.
> 
> OTOH running plasma as su worked for many years - and I am aware of the
> possible risk. ;)
Plasma session as root is unsupported and will be RESOLVED/INVALID.

(In reply to Tom from comment #2)
> several users using binary distributions had the same problem with a crashing
> plasmashell... I've read about qtqml v5.15.2 should have fixed the segfault?
You're first and only report of this kind in Gentoo. If you point me to where you read that, possibly even with link to the commit, then I will happily try and backport to 5.15.1.
Comment 4 Tom 2020-10-18 10:33:58 UTC
(In reply to Andreas Sturmlechner from comment #3)
> (In reply to Tom from comment #2)
> > several users using binary distributions had the same problem with a crashing
> > plasmashell... I've read about qtqml v5.15.2 should have fixed the segfault?
> You're first and only report of this kind in Gentoo. If you point me to
> where you read that, possibly even with link to the commit, then I will
> happily try and backport to 5.15.1.

Sadly I've killed my browser history yesterday and tried hard to find it again this morning, but without success...

In the meantime I've moved my old ~/.config directory out of the way, as it holds configurations for kde 4 and 5, and started the plasma desktop freshly as root - now it works again after reconfiguring it. :)

Looks like some of the old configuration files caused the segfault.

Sorry for making panic on this topic. ;)

CU Tom