Bug 98464 - Xorg crashes with xserver-xorg-input-libinput 0.20.0
Summary: Xorg crashes with xserver-xorg-input-libinput 0.20.0
Alias: None
Product: xorg
Classification: Unclassified
Component: Input/libinput (show other bugs)
Version: 7.7 (2012.06)
Hardware: x86-64 (AMD64) Linux (All)
: medium major
Assignee: Peter Hutterer
QA Contact: Xorg Project Team
Depends on:
Reported: 2016-10-28 01:59 UTC by Jean-Philippe MENGUAL
Modified: 2016-12-21 00:04 UTC (History)
3 users (show)

See Also:
i915 platform:
i915 features:

Patch proposal (409 bytes, patch)
2016-10-28 01:59 UTC, Jean-Philippe MENGUAL
no flags Details | Splinter Review
Full Xorg log (25.69 KB, text/plain)
2016-11-08 03:44 UTC, Jean-Philippe MENGUAL
no flags Details
xorg.log (26.76 KB, text/plain)
2016-12-05 01:10 UTC, Peter Hutterer
no flags Details
backtrace (543 bytes, text/plain)
2016-12-14 06:55 UTC, Samuel Thibault
no flags Details
backtrace (2.10 KB, text/plain)
2016-12-14 10:57 UTC, Samuel Thibault
no flags Details
debugging information (15.50 KB, text/plain)
2016-12-18 17:30 UTC, Samuel Thibault
no flags Details

Description Jean-Philippe MENGUAL 2016-10-28 01:59:11 UTC
Created attachment 127578 [details] [review]
Patch proposal


On a Debian Stretch, randomly, after several minutes, X crashes.

Here are lines I get:
[957598.965] (EE).
[957598.965] (EE) Backtrace:
[957598.966] (EE) 0: /usr/lib/xorg/Xorg (xorg_backtrace+0x4a) [0x557cd4d7601a]
[957598.966] (EE) 1: /usr/lib/xorg/Xorg (0x557cd4bbc000+0x1be389) [0x557cd4d7a389]
[957598.966] (EE) 2: /lib/x86_64-linux-gnu/libc.so.6 (0x7f55d7ad0000+0x33040) [0x7f55d7b03040]
[957598.966] (EE) 3: /usr/lib/x86_64-linux-gnu/libinput.so.10 (0x7f55d0e36000+0xf214) [0x7f55d0e45214]
[957598.966] (EE) 4: /usr/lib/xorg/Xorg (XkbDDXKeybdCtrlProc+0x47) [0x557cd4d15127]
[957598.966] (EE) 5: /usr/lib/xorg/Xorg (XkbComputeControlsNotify+0x1a7) [0x557cd4d26387]
[957598.966] (EE) 6: /usr/lib/xorg/Xorg (0x557cd4bbc000+0x16b8c5) [0x557cd4d278c5]
[957598.966] (EE) 7: /usr/lib/xorg/Xorg (0x557cd4bbc000+0x1b6ae0) [0x557cd4d72ae0]
[957598.966] (EE) 8: /usr/lib/xorg/Xorg (WaitForSomething+0xd14) [0x557cd4d738a4]
[957598.967] (EE) 9: /usr/lib/xorg/Xorg (0x557cd4bbc000+0x53e9e) [0x557cd4c0fe9e]
[957598.967] (EE) 10: /usr/lib/xorg/Xorg (0x557cd4bbc000+0x58073) [0x557cd4c14073]
[957598.967] (EE) 11: /lib/x86_64-linux-gnu/libc.so.6 (__libc_start_main+0xf1) [0x7f55d7af02b1]
[957598.967] (EE) 12: /usr/lib/xorg/Xorg (_start+0x2a) [0x557cd4bfdfea]
[957598.967] (EE).
[957598.967] (EE) Segmentation fault at address 0xd0
[957598.967] (EE).
Fatal server error:
[957598.967] (EE) Caught signal 11 (Segmentation fault). Server aborting
[957598.967] (EE).
[957598.967] (EE).
Please consult the The X.Org Foundation support.
<------> at http://wiki.x.org
 for help..
[957598.967] (EE) Please also check the log file at "/var/log/Xorg.0.log" for additional information.
[957598.967] (EE).
[957598.967] (EE) Server terminated with error (1). Closing log file.

Samuel Thibault wrote a patch I'm testing. If I no longer have crashes in next 15 days, I'll report you should apply it to fix the problem.

Comment 1 Peter Hutterer 2016-10-28 02:40:31 UTC
do you get anything else in the log before? looks like this should only happen if the device disappears and that should show up in the log. Can you attach the full log please?
Comment 2 Jean-Philippe MENGUAL 2016-11-08 03:44:36 UTC
Created attachment 127828 [details]
Full Xorg log
Comment 3 Jean-Philippe MENGUAL 2016-11-08 03:46:50 UTC

Sorry for delay. I didn't have available what you request, so needed to collect. Here's a full log for Xorg then.

FYI: no longer crash since I've patched with attached patch.

Comment 4 Peter Hutterer 2016-11-08 06:16:13 UTC
Can you install the debuginfo packages please and figure out where exactly this is coming from? I need to know what's triggering this crash so I can reproduce it here.


Specifically, the two lines between WaitForSomething and XkbComputeControlsNotify are necessary. Thanks
Comment 5 Jean-Philippe MENGUAL 2016-12-04 10:25:06 UTC

The full log is here:

Tell me if it's helpful, otherwise I need to know what I should install and what files I should examine.

Comment 6 Peter Hutterer 2016-12-05 01:10:24 UTC
Created attachment 128337 [details]

Xorg.log from comment #5

Please don't link to pastebins, they have a habit of expiring before we get to read them.
Comment 7 Peter Hutterer 2016-12-05 03:10:09 UTC
hmm, still missing the important bits. Please follow the instruction here to figure out the missing two lines in the backtrace (the two below XkbComputeControlsNotify)
Comment 8 Jean-Philippe MENGUAL 2016-12-06 07:40:04 UTC

Sorry but how should I apply this tool in my case? Once installed. I run it after crash? I run eu-addr2line /usr/bin/Xorg until crash? I'm unable to apply for me:
eu-addr2line -e /opt/xorg/bin/Xorg 0x48d1a4

Does it apply on Xorg.log or for a new running session?

Comment 9 Peter Hutterer 2016-12-06 08:04:59 UTC
you run it against /usr/bin/Xorg but the binary has to be the same as the one that produced the crash. if you updated since, you need to re-produce the log. And then you just run
eu-addr2line -e /usr/bin/Xorg 0x555dc55e08c5
eu-addr2line -e /usr/bin/Xorg 0x555dc562bae0
That should give us the two locations of the callstack that matter. Hopefully :)

Oh, and now I see that this is during the vt switch, can you try version 0.22 please, that has some extra protections against device removal crashes - this may be the issue here.
Comment 10 Jean-Philippe MENGUAL 2016-12-13 18:56:40 UTC

ok I'll try this week. Do I have a solution to do this from a Lightdm session manager? To run X in debug mode from login in Lifhtdm?

Comment 11 Peter Hutterer 2016-12-13 22:18:26 UTC
note that to run eu-addr2line you only need the address and the same binary around, i.e. you can still run this now if you haven't updated since, it should only take a minute.

as for lightdm debug - sorry, no idea but there is no real "debug" mode in X anyway, the only thing you can do is to increase the verbosity in the log file. Which probably wouldn't help much in this case, the backtrace addresses will be more useful. 

After a bit of googling, the bug below suggests there's a way to pass commandline flags though, try -logverbose 7 or 10 to see more log messages.
Comment 12 Samuel Thibault 2016-12-14 06:55:21 UTC
Created attachment 128462 [details]
Comment 13 Samuel Thibault 2016-12-14 06:56:23 UTC
I forgot to write: also, the related users have the habit of switching
to a text VT and work there with brltty while Xorg is still running in
the other VT.
Comment 14 Samuel Thibault 2016-12-14 07:06:58 UTC
Grmbl, it seems that bugzilla ate my comment:  Hello,  Here is a backtrace obtained in a crash very similar to the situation here, which is what prompted me to write the patch that Jean-Philippe attached to this bug.  The proposed patch also did fix the following bug report:  https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=838703  The relation between all these crashes is that the users have brltty running, which runs a uinput device.  Jean-Philippe, could you try Debian's xserver-xorg-input-libinput 0.23.0-1, as suggested by Emilio in the Debian bug entry?  Samuel
Comment 15 Emilio Pozuelo Monfort 2016-12-14 10:13:07 UTC
(In reply to Samuel Thibault from comment #12)
> Created attachment 128462 [details]
> backtrace

Looks like your backtrace attachment is actually the comment that disappeared. Can you attach the proper backtrace?

Comment 16 Samuel Thibault 2016-12-14 10:57:10 UTC
Created attachment 128466 [details]


Anyway, here is the backtrace again
Comment 17 Peter Hutterer 2016-12-14 21:37:21 UTC
backtrace suggests that the device is already NULL by the time the led updated is called, if so that's another high chance that the fix from 0.23 addresses this issue, I really need someone to test that version please.
Comment 18 Samuel Thibault 2016-12-18 16:25:26 UTC

In http://bugs.debian.org/838703 , Sebastian Humenda reports that 0.23 doesn't fix the issue, and he has to apply the proposed patch to avoid the crashes.

Comment 19 Samuel Thibault 2016-12-18 17:30:28 UTC
Created attachment 128529 [details]
debugging information

FYI, I still have the core file, and I have rebuilt a chroot containing the proper versions, which I have uploaded to:


after chrooting into it, run

cd /var/tmp/debug/debug/debug/debug/debug/
gdb /usr/lib/xorg/Xorg  core

and the source lines are all available and correct.

I'm also attaching to this bug some debugging prints from there.
Comment 20 Sebastian Humenda 2016-12-19 17:42:05 UTC
I can still confirm the issue with the latest version, 0.23.0. When I apply the patch, the problem is gone.
Comment 21 Peter Hutterer 2016-12-20 10:11:25 UTC
Comment 22 Peter Hutterer 2016-12-21 00:04:27 UTC
commit f47f78eb0bd9fba455f01c8c6dead3bd75242b2b
Author: Peter Hutterer <peter.hutterer@who-t.net>
Date:   Tue Dec 20 15:36:55 2016 +1000

    Ignore LED updates for disabled devices

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