[Spice-devel] crashes / Assertion `uxa_pixmap_is_offscreen(src_pixmap)' failed

[Daniel Pocock]

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On 02/05/17 14:46, Christophe Fergeau wrote:
> On Tue, May 02, 2017 at 02:16:00PM +0200, Daniel Pocock wrote:
>> 
>> 
>> On 02/05/17 13:54, Christophe Fergeau wrote:
>>> On Tue, May 02, 2017 at 01:46:20PM +0200, Daniel Pocock wrote:
>>>> 
>>>> 
>>>> On 02/05/17 12:43, Christophe Fergeau wrote:
>>>>> On Tue, May 02, 2017 at 11:39:08AM +0200, Daniel Pocock
>>>>> wrote:
>>>>>> 
>>>>>> 
>>>>>> Hi,
>>>>>> 
>>>>>> I've observed that the Xorg process in my virtual server
>>>>>>  sometimes crashes when I launch Firefox.  Xorg.0.log had
>>>>>> an error about "Out of video memory: Could not allocate
>>>>>> 7274816 bytes", so I increased video RAM from 64MB to
>>>>>> 256MB.  On the last crash the error about memory was not
>>>>>> there, but I found this at the end of Xorg.0.log:
>>>>>> 
>>>>>> [170197.066] qxl_surface_create: Bad bpp: 1 (1)
>>>>>> [170197.076] qxl_surface_create: Bad bpp: 1 (1)
>>>>>> [170228.641] qxl_surface_create: Bad bpp: 1 (1)
>>>>>> [170281.094] qxl_surface_create: Bad bpp: 1 (1)
>>>>>> [170281.641] qxl_surface_create: Bad bpp: 1 (1)
>>>>> 
>>>>> These ones keep happening I think, and are harmless
>>>>> 
>>>>>> 
>>>>>> and in journalctl I found:
>>>>>> 
>>>>>> gdm-Xorg-:0[1538]: qxl_surface_create: Bad bpp: 1 (1) 
>>>>>> iceweasel.desktop[4967]: Gtk-Message: Failed to load
>>>>>> module "canberra-gtk-module" gdm-Xorg-:0[1538]:
>>>>>> qxl_surface_create: Bad bpp: 1 (1) gdm-Xorg-:0[1538]:
>>>>>> qxl_surface_create: Bad bpp: 1 (1) gdm-Xorg-:0[1538]:
>>>>>> Xorg: ../../../src/uxa/uxa-glyphs.c:991:
>>>>>> uxa_glyphs_via_mask: Assertion
>>>>>> `uxa_pixmap_is_offscreen(src_pixmap)' failed.
>>>>>> 
>>>>>> at the moment of the crash.  I opened a Debian bug[1]
>>>>>> with that error.
>>>>> 
>>>>> Would you have a core file when that happens?
>>>>> 
>>>> 
>>>> Not yet, but I'd be happy to try and get one.  Would you be
>>>> able to suggest how I tweak my system to generate core files
>>>> for the Xorg process?  Should I just replace the Xorg binary
>>>> with a wrapper script or is there a more official way to do
>>>> it by modifying /lib/systemd/system/gdm3.service or something
>>>> else?
>>> 
>>> On my f26 system, coredumpctl is just magic to grab coredumps,
>>> but I don't know how much integration work is needed. An
>>> alternative is to run a screen/tmux, and attach gdb to the
>>> running Xorg process in there, and switch to a VT once it
>>> crashed (hopefully this should be possible). Or I guess you can
>>> just enable core generation system-wide, and grab it in the
>>> location where it landed (this is defined in /proc/xxx)
>>> 
>> 
>> Thanks for that tip, I'm always glad to learn something new.  I
>> did this :
>> 
>> apt-get install -t jessie-backports systemd-coredump
>> 
>> and then I checked it is there:
>> 
>> $ sysctl -a | grep core_patt kernel.core_pattern =
>> |/lib/systemd/systemd-coredump %P %u %g %s %t 9223372036854775808
>> %e
>> 
>> I tried killing my shell with SEGV and it looks like I captured
>> somethin g:
>> 
>> $ sudo coredumpctl list TIME                            PID   UID
>> GID SIG PRESENT EXE Tue 2017-05-02 14:13:14 CEST   6152  1000
>> 1000  11 * /bin/bash
>> 
>> 
>> Am I all set now for the next Xorg crash or is there anything
>> else that might be worth tweaking?
> 
> I'd make sure that "coredumpctl gdb" is giving you a backtrace, 
> otherwise you are all set.
> 

I tried that, looks good.

I also did

 apt-get install gdb xserver-xorg-core-dbg xserver-xorg-video-qxl-dbg

to get the symbols.

Regards,

Daniel
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