WARNING regarding 4.3.x kernel

[Cristian Sava]

I have a F23 server with minimal working X (no desktop).
All was working well with kernel-4.2.x
With kernel-4.3.x I get (in xterm):

[a53@s ~]$ su -c virt-manager
Password: 
[a53@s ~]$ No protocol specified
Unable to init server: Could not connect: Connection refused
(virt-manager:54862): Gtk-CRITICAL **: gtk_settings_get_for_screen:
assertion 'GDK_IS_SCREEN (screen)' failed
[a53@s ~]$ 

journalctl gives:

kernel: virt-manager[8896]: segfault at 0 ip 00007f612fce78a9 sp
00007ffe5a45e580 error 4 in libgtk-3.so.0.1800.6[7f612fa2d000+710000]
kernel: BUG: unable to handle kernel NULL pointer dereference at
0000000000000060

Searching the web I discovered that during years this error shows up
from time to time across different distributions (including Fedora).
This time it seems to be kernel related and does not show up with
Gnome.

C.S

[thibaut noah]

Did you report it? seems like someone forgot to check the pointer before
accessing it.

2016-01-21 9:12 GMT+01:00 Cristian Sava <csava(a)central.ucv.ro&gt;:

>  I have a F23 server with minimal working X (no desktop).
>  All was working well with kernel-4.2.x
>  With kernel-4.3.x I get (in xterm):
>
>  [a53@s ~]$ su -c virt-manager
>  Password:
>  [a53@s ~]$ No protocol specified
>  Unable to init server: Could not connect: Connection refused
>  (virt-manager:54862): Gtk-CRITICAL **: gtk_settings_get_for_screen:
>  assertion 'GDK_IS_SCREEN (screen)' failed
>  [a53@s ~]$
>
>  journalctl gives:
>
>  kernel: virt-manager[8896]: segfault at 0 ip 00007f612fce78a9 sp
>  00007ffe5a45e580 error 4 in libgtk-3.so.0.1800.6[7f612fa2d000+710000]
>  kernel: BUG: unable to handle kernel NULL pointer dereference at
>  0000000000000060
>
>  Searching the web I discovered that during years this error shows up
>  from time to time across different distributions (including Fedora).
>  This time it seems to be kernel related and does not show up with
>  Gnome.
>
>  C.S
>
>  --
>  users mailing list
>  users(a)lists.fedoraproject.org
>  To unsubscribe or change subscription options:
>  https://admin.fedoraproject.org/mailman/listinfo/users
>  Fedora Code of Conduct: http://fedoraproject.org/code-of-conduct
>  Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
>  Have a question? Ask away: http://ask.fedoraproject.org
>

[Cristian Sava]

On Thu, 2016-01-21 at 11:55 +0100, thibaut noah wrote:
>  Did you report it? seems like someone forgot to check the pointer
>  before accessing it. 
Not yet. Further investigation is needed.
What I've done now in virtual environment:
1-Install F23 server, default, no options.
2-Update, reboot
3-Install minimal X:
  dnf groupinstall base-x
  dnf install xterm xorg-x11-xbitmaps xorg-x11-fonts-ISO8859-15-75dpi
xorg-x11-fonts-ISO8859-15-100dpi xorg-x11-fonts-misc
  dnf install xorg-x11-xdm xorg-x11-xsm xorg-x11-xkb-extras xorg-x11-
xfs xorg-x11-xfs-utils xorg-x11-twm
4-Install VM environment:
  dnf install qemu qemu-common qemu-guest-agent qemu-img qemu-kvm qemu-
kvm-tools qemu-user qemu-system-x86
  dnf install libvirt virt-manager virt-install
5-Switch to graphical and the error is there:
  su -c virt-manager
6-Reboot and add very basic gnome:
  dnf install gnome-desktop3 gnome-commander gnome-abrt gnome-disk-
utility gnome-menus gnome-shell gnome-shell-extension-common gnome-
terminal gnome-themes-standard gnome-tweak-tool
7-reboot, switch to graphical:
 a) Still error in xterm: su -c virt-manager
 b) Surprise: the VM icon works as expected!
Same result on a phisical machine with the difference that trying to
switch back to multi-user freezes the box.
Anyone else want to test it?

>  2016-01-21 9:12 GMT+01:00 Cristian Sava
> <csava(a)central.ucv.ro&gt;:
>  > I have a F23 server with minimal working X (no desktop).
>  > All was working well with kernel-4.2.x
>  > With kernel-4.3.x I get (in xterm):
>  > 
>  > [a53@s ~]$ su -c virt-manager
>  > Password: 
>  > [a53@s ~]$ No protocol specified
>  > Unable to init server: Could not connect: Connection refused
>  > (virt-manager:54862): Gtk-CRITICAL **: gtk_settings_get_for_screen:
>  > assertion 'GDK_IS_SCREEN (screen)' failed
>  > [a53@s ~]$ 
>  > 
>  > journalctl gives:
>  > 
>  > kernel: virt-manager[8896]: segfault at 0 ip 00007f612fce78a9 sp
>  > 00007ffe5a45e580 error 4 in libgtk-
>  > 3.so.0.1800.6[7f612fa2d000+710000]
>  > kernel: BUG: unable to handle kernel NULL pointer dereference at
>  > 0000000000000060
>  > 
>  > Searching the web I discovered that during years this error shows
>  > up
>  > from time to time across different distributions (including
>  > Fedora).
>  > This time it seems to be kernel related and does not show up with
>  > Gnome.
>  > 
>  > C.S
>  >

[Chris Murphy]

Weird. I've been using virt-manager with kernel 4.3.3 and 4.4.0 on
Fedora 23 for some time without problems. Maybe check AVC messages?

ausearch -m AVC

Maybe it's worth relabeling:

restorecon -rv /

I don't know why but even after a clean install and no updates,
restorecon fixes labels. It's like they aren't set correctly to start
with for some reason. And then after any update I run it and it fixes
more things each time. Kinda annoying really. I don't feel like I
ought to need to relabel manually after every update. Maybe more than
one label is valid, just that one is more valid than another and
that's why the install label is sometimes different from post-install
label.

Chris Murphy

[Patrick O'Callaghan]

On Thu, 2016-01-21 at 12:22 -0700, Chris Murphy wrote:
>  Weird. I've been using virt-manager with kernel 4.3.3 and 4.4.0
> on
>  Fedora 23 for some time without problems. Maybe check AVC messages?
>  
>  ausearch -m AVC
>  
>  Maybe it's worth relabeling:
>  
>  restorecon -rv /
>  
>  I don't know why but even after a clean install and no updates,
>  restorecon fixes labels. It's like they aren't set correctly to start
>  with for some reason. And then after any update I run it and it fixes
>  more things each time. Kinda annoying really. I don't feel like I
>  ought to need to relabel manually after every update. Maybe more than
>  one label is valid, just that one is more valid than another and
>  that's why the install label is sometimes different from post-install
>  label. 
How is this related to the topic of this thread?

poc

[Cristian Sava]

On Thu, 2016-01-21 at 14:33 +0200, Cristian Sava wrote:
>  On Thu, 2016-01-21 at 11:55 +0100, thibaut noah wrote:
>  > Did you report it? seems like someone forgot to check the pointer
>  > before accessing it.
>  Not yet. Further investigation is needed.
>  What I've done now in virtual environment:
>  1-Install F23 server, default, no options.
>  2-Update, reboot
>  3-Install minimal X:
>    dnf groupinstall base-x
>    dnf install xterm xorg-x11-xbitmaps xorg-x11-fonts-ISO8859-15-75dpi
>  xorg-x11-fonts-ISO8859-15-100dpi xorg-x11-fonts-misc
>    dnf install xorg-x11-xdm xorg-x11-xsm xorg-x11-xkb-extras xorg-x11-
>  xfs xorg-x11-xfs-utils xorg-x11-twm
>  4-Install VM environment:
>    dnf install qemu qemu-common qemu-guest-agent qemu-img qemu-kvm
>  qemu-
>  kvm-tools qemu-user qemu-system-x86
>    dnf install libvirt virt-manager virt-install
>  5-Switch to graphical and the error is there:
>    su -c virt-manager
>  6-Reboot and add very basic gnome:
>    dnf install gnome-desktop3 gnome-commander gnome-abrt gnome-disk-
>  utility gnome-menus gnome-shell gnome-shell-extension-common gnome-
>  terminal gnome-themes-standard gnome-tweak-tool
>  7-reboot, switch to graphical:
>   a) Still error in xterm: su -c virt-manager
>   b) Surprise: the VM icon works as expected!
>  Same result on a phisical machine with the difference that trying to
>  switch back to multi-user freezes the box.
>  Anyone else want to test it?
>  
>  > 2016-01-21 9:12 GMT+01:00 Cristian Sava <csava(a)central.ucv.ro&gt;:
>  > > I have a F23 server with minimal working X (no desktop).
>  > > All was working well with kernel-4.2.x
>  > > With kernel-4.3.x I get (in xterm):
>  > > 
>  > > [a53@s ~]$ su -c virt-manager
>  > > Password: 
>  > > [a53@s ~]$ No protocol specified
>  > > Unable to init server: Could not connect: Connection refused
>  > > (virt-manager:54862): Gtk-CRITICAL **:
>  > > gtk_settings_get_for_screen:
>  > > assertion 'GDK_IS_SCREEN (screen)' failed
>  > > [a53@s ~]$ 
>  > > 
>  > > journalctl gives:
>  > > 
>  > > kernel: virt-manager[8896]: segfault at 0 ip 00007f612fce78a9 sp
>  > > 00007ffe5a45e580 error 4 in libgtk-
>  > > 3.so.0.1800.6[7f612fa2d000+710000]
>  > > kernel: BUG: unable to handle kernel NULL pointer dereference at
>  > > 0000000000000060
>  > > 
>  > > Searching the web I discovered that during years this error shows
>  > > up
>  > > from time to time across different distributions (including
>  > > Fedora).
>  > > This time it seems to be kernel related and does not show up with
>  > > Gnome.
>  > > 
>  > > C.S
>  > > 
>   
Tested with kernel-4.3.4 (x64 from koji) and the problem persist.

C.S.