Bug 314663 - Input freezes after locking screen if not using the Desktop Widgets locker
Summary: Input freezes after locking screen if not using the Desktop Widgets locker
Status: RESOLVED FIXED
Alias: None
Product: kscreensaver
Classification: Miscellaneous
Component: locker-qml (show other bugs)
Version: 4.10.0
Platform: Arch Linux Linux
: NOR critical
Target Milestone: ---
Assignee: Plasma Bugs List
URL:
Keywords:
: 328021 (view as bug list)
Depends on:
Blocks:
 
Reported: 2013-02-08 11:39 UTC by Chris Warrick
Modified: 2015-04-20 20:52 UTC (History)
17 users (show)

See Also:
Latest Commit:
Version Fixed In:


Attachments
Strace of kscreenlocker_greet (1.99 MB, text/plain)
2013-08-06 20:15 UTC, Nick
Details

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Description Chris Warrick 2013-02-08 11:39:59 UTC
In 4.9, I used the OpenGL screensaver + widgets overlay mode of kscreensaver.  It worked really nicely.  After an upgrade to 4.10, only the Desktop Widgets + plain background works, other two options (Plain locker and Screen saver).  The other two result in an input freeze (the system doesn’t take kb/mouse input, but image on the screen is still shown and updated) that is recoverable only using Ctrl+Alt+Backspace.

Reproducible: Always

Steps to Reproduce:
1. Set screen locker to “simple locker” or “screen saver”.
2. Lock the screen.
Actual Results:  
Input freezed, display — not.

Expected Results:  
Screen nicely locked.

Using NVIDIA GeForce GTS 450 + Arch Linux [testing] + proprietary drivers.
Comment 1 John Layt 2013-02-12 21:27:06 UTC
I have exactly the same issues on openSuse 12.2, mouse and keyboard input other than super X keys are ignored, but it doesn't happen every time the screen locks.  If I go to unlock the screen the underlying desktop is immediately displayed rather than the unlock screen and I can only recover vie ctrl-alt-dbackspace.  On Thiago's advice I switched to the virtual console and ran "xwininfo -display :0" which complained it couldn't grab the mouse.  This apparently means an app froze up while it held the X grab, but killing all running apps failed to release the lock, so my assumption is that the screen locker itself has frozen.
Comment 2 devsk 2013-02-16 02:51:02 UTC
I have the exact same behaviour!

Any ideas if someone's working on  a fix? This kills the desktop for me. I need to be able to lock my desktop. Right now, not only I can't lock, but trying to do so means restarting kde, killing all apps running in it. This is a serious bug.
Comment 3 devsk 2013-02-16 08:05:00 UTC
There is some generic (library level) mouse grabbing issue with KDE. If I enable "Mouse Navigation" using the numpad, just pressing shift-insert is enough to lock my mouse. Nothing works after that. Only option is to ctrl-alt-f1, login and issue the 'export DISPLAY=:0 ; qdbus org.kde.ksmserver /KSMServer logout 0 0 0' to logout and log back in.

This used to work at some point obviously!
Comment 4 devsk 2013-02-27 03:59:40 UTC
Is anybody working on this very serious issue? How are people locking there workstations without the fix for this bug?
Comment 5 devsk 2013-02-27 07:54:17 UTC
I give up and move to use xlock....:)
Comment 6 John Layt 2013-02-27 14:51:27 UTC
You can work around the bug by going into System Settings / Display and Monitor / Screen Locker and selecting the "Simple Locker" type.  After that it works fine.
Comment 7 devsk 2013-02-27 16:02:58 UTC
John: are u even reading the bug report?....:-) Simple Locker is what is broken. At least for me.

"How are people locking there workstations without the fix for this bug?"

If simple locker worked, I wouldn't ask that...or move to xlock...:D

But here is a clue I got: running /usr/lib/kde4/libexec/kscreenlocker_g segfaults. So, ksmserver keeps on spawning it, input is frozen in the mean time because of locker process segfaulting.
Comment 8 devsk 2013-02-27 16:30:00 UTC
Not much but see if it helps:

(gdb) bt
#0  0x080590a3 in ScreenLocker::UnlockApp::desktopResized() ()
#1  0x00000000 in ?? ()

disassemble:

   0x08059023 <+4403>:  je     0x8058b12 <_ZN12ScreenLocker9UnlockApp14desktopResizedEv+3106>
   0x08059029 <+4409>:  mov    0x94(%esp),%eax
   0x08059030 <+4416>:  mov    %eax,(%esp)
   0x08059033 <+4419>:  call   0x8051170
   0x08059038 <+4424>:  mov    0x180(%esp),%edx
   0x0805903f <+4431>:  movl   $0x0,0x10(%esp)
   0x08059047 <+4439>:  movl   $0x805f372,0xc(%esp)
   0x0805904f <+4447>:  movl   $0x805f383,0x4(%esp)
   0x08059057 <+4455>:  mov    %eax,(%esp)
   0x0805905a <+4458>:  mov    %edx,0x8(%esp)
   0x0805905e <+4462>:  call   0x80504d0
   0x08059063 <+4467>:  jmp    0x8058b12 <_ZN12ScreenLocker9UnlockApp14desktopResizedEv+3106>
   0x08059068 <+4472>:  nop
   0x08059069 <+4473>:  lea    0x0(%esi,%eiz,1),%esi
   0x08059070 <+4480>:  lea    0xc0(%esp),%eax
   0x08059077 <+4487>:  movl   $0x805f353,0x4(%esp)
   0x0805907f <+4495>:  mov    %eax,(%esp)
   0x08059082 <+4498>:  call   0x8051010
   0x08059087 <+4503>:  sub    $0x4,%esp
   0x0805908a <+4506>:  mov    0xc0(%esp),%eax
   0x08059091 <+4513>:  mov    0xc(%eax),%edi
   0x08059094 <+4516>:  mov    0x94(%esp),%eax
   0x0805909b <+4523>:  mov    %eax,(%esp)
   0x0805909e <+4526>:  call   0x8051170
=> 0x080590a3 <+4531>:  mov    (%eax),%edx
---Type <return> to continue, or q <return> to quit---
   0x080590a5 <+4533>:  mov    %eax,(%esp)
   0x080590a8 <+4536>:  call   *(%edx)
   0x080590aa <+4538>:  mov    %edi,0x4(%esp)
   0x080590ae <+4542>:  mov    %eax,(%esp)
   0x080590b1 <+4545>:  call   0x80502d0
   0x080590b6 <+4550>:  mov    0xc0(%esp),%edx
   0x080590bd <+4557>:  mov    %eax,%edi
   0x080590bf <+4559>:  lock decl (%edx)
   0x080590c2 <+4562>:  setne  %al
   0x080590c5 <+4565>:  test   %al,%al
   0x080590c7 <+4567>:  jne    0x80590d8 <_ZN12ScreenLocker9UnlockApp14desktopResizedEv+4584>
   0x080590c9 <+4569>:  mov    0xc0(%esp),%eax
   0x080590d0 <+4576>:  mov    %eax,(%esp)
   0x080590d3 <+4579>:  call   0x80510f0
   0x080590d8 <+4584>:  cmp    $0xffffffff,%edi
   0x080590db <+4587>:  je     0x8058a3b <_ZN12ScreenLocker9UnlockApp14desktopResizedEv+2891>
Comment 9 Ryan Reamsbottom 2013-03-08 18:12:06 UTC
Can confirm here (Kubuntu 13.04, kde-workspace-bin Version: 4:4.10.1b-0ubuntu1)  - Simple Locker returns a black screen with no way to unlock.  Switching to Desktop Widgets allows me to unlock the screen.
Comment 10 devsk 2013-04-25 17:23:19 UTC
Anybody doing anything for this bug? It locks the system hard and should be considered a blocker bug.
Comment 11 Christoph Feck 2013-04-25 18:36:47 UTC
Is the simple locker the default setting for a fresh user account?
Comment 12 slash2bot 2013-05-23 18:36:09 UTC
I can confirm this bug. Upgraded to 13.04 (from 12.10, which was updated from 12.04).
Comment 13 devsk 2013-05-23 19:39:03 UTC
(In reply to comment #12)
> I can confirm this bug. Upgraded to 13.04 (from 12.10, which was updated
> from 12.04).

Vote for it then. I still am stunned at the lack of attention this bug gets. You lock your screen, you have to kill the whole desktop to use it again. How can a bug like this go unfixed in so many releases?
Comment 14 Nick 2013-08-06 20:15:39 UTC
Created attachment 81590 [details]
Strace of kscreenlocker_greet
Comment 15 Nick 2013-08-06 20:17:00 UTC
I had a similar problem then found this thread the other day. I uploaded my strace of the process.

https://bugs.kde.org/show_bug.cgi?id=322582
Comment 16 Chris Warrick 2013-08-15 13:24:16 UTC
I found the culprit on my side.  I fixed the problem by disabling Bespin’s translucency for kscreenlocker and kscreenlocker_greet.
Comment 17 Nick 2013-08-15 15:34:49 UTC
Could you elaborate? I'm not familiar with Bespin and/or how to disable this.

(In reply to comment #16)
> I found the culprit on my side.  I fixed the problem by disabling Bespin’s
> translucency for kscreenlocker and kscreenlocker_greet.
Comment 18 Chris Warrick 2013-08-15 15:58:09 UTC
(In reply to comment #17)
> Could you elaborate? I'm not familiar with Bespin and/or how to disable this.
> 
> (In reply to comment #16)
> > I found the culprit on my side.  I fixed the problem by disabling Bespin’s
> > translucency for kscreenlocker and kscreenlocker_greet.

System Settings → Application Appearance → Configure → Windows → Translucent Windows (Experimental!) → Exclude.
Comment 19 Eric Francis 2013-08-15 17:57:43 UTC
Confirmed that adding kscreenlocker and kscreenlocker_greet to Bespin's translucency exclusion list resolves the problem.
We should also verify if other style engines that do window transparency (Oxygen Transparent, and QtCurve (and the gtk engine?)) also have this problem and if so is there (currently) a way to disable transparency for these specific applications, or if further changes need to be made to those engines.
Comment 20 devsk 2013-08-15 18:14:31 UTC
I don't have the settings mentioned above. I am using plain Oxygen as my style. How do I get past the frozen input on locking screen?

I use Qtcurve for GTK apps.
Comment 21 Eric Francis 2013-08-15 18:17:19 UTC
QtCurve confirmed to have the problem when in QtCurve's config dialog, under Opacity the Windows opacity percent is less than 100%. 
    Fix: under Applications, ensure that kscreenlocker_greet (in addition to kscreenlocker) is included in the No background opacity list.

Oxygen Transparent confirmed to have the problem.
    Fix: in Oxygen Transparent's config -> General -> Exceptions... -> check kscreenlocker and add kscreenlocker_greet
Comment 22 Eric Francis 2013-08-15 18:23:27 UTC
(In reply to comment #20)
> I don't have the settings mentioned above. I am using plain Oxygen as my
> style. How do I get past the frozen input on locking screen?
> 
> I use Qtcurve for GTK apps.

I tried it just now with vanilla Oxygen (4.10) and did not run into the problem - the screensaver displayed as expected, on user input the screenlocker showed up and I was able to unluck as expected.

(btw, I found the following command to work in KDE 4.10 to disable the screenlocker if it can't be unlocked by normal means:
qdbus org.kde.kscreenlocker_greet-xxxx /MainApplication quit
replacing xxxx with the pid of the kscreenlocker_greet process)
Comment 23 devsk 2013-08-15 18:24:33 UTC
Removing Qtcurve from GTK and disabling translucency altogether does not fix this issue for me. The input still freezes and kscreenlocker_g keeps on getting reforked.
Comment 24 devsk 2013-08-15 18:27:20 UTC
> qdbus org.kde.kscreenlocker_greet-xxxx /MainApplication quit 
> replacing xxxx with the pid of the kscreenlocker_greet process)

That won't work if  kscreenlocker_greet PID is changing every 1 second, meaning kscreenlocker_greet is SEGV'ing repeatedly. Please read my responses above.
Comment 25 Thomas Lübking 2013-08-15 18:45:36 UTC
(In reply to comment #19)
> Confirmed that adding kscreenlocker and kscreenlocker_greet to Bespin's
> translucency exclusion list resolves the problem.

Interesting.
The Problem here will be that turning a window ARGB in fact creates a new (with new WId)

I'll blacklist them internally.

The window can for later Bespin (and Oxygen-Transparent, Hugo?) versions add 1<<4 to the dynamic Qt property "KStyleFeatureRequest" (not simply override it, but fetch the property value().toUInt() and set it back or'd by 1<<4
Comment 26 Thomas Lübking 2013-11-24 19:40:44 UTC
*** Bug 328021 has been marked as a duplicate of this bug. ***
Comment 27 Nikita Zlobin 2013-11-25 02:24:40 UTC
I recently made a report, which could be about same bug, but in 4.11.3 too: https://bugs.kde.org/show_bug.cgi?id=327567
Comment 28 Nikita Zlobin 2013-11-25 03:05:18 UTC
(In reply to comment #27)
> I recently made a report, which could be about same bug, but in 4.11.3 too:
> https://bugs.kde.org/show_bug.cgi?id=327567

Oops, wrong bug. I just picked kwin-related bug from My Bugs saved searches. I did one yesterday, but many of them are not in list.
Comment 29 Anssi Saari 2013-12-23 09:50:59 UTC
I found one reason why this bug happens: kscreenlocker_greet has a dependency on kdm, at least on Sabayon Linux. It needs some plugins provided by the kdm package which is why it crashes repeatedly.

Just installing kdm made screenlocking work for me. There's a related KDE bug https://bugs.kde.org/show_bug.cgi?id=314901 and a related Sabayon bug https://bugs.sabayon.org/show_bug.cgi?id=4235
Comment 30 artephius 2014-01-13 17:22:32 UTC
(In reply to comment #29)
> I found one reason why this bug happens: kscreenlocker_greet has a
> dependency on kdm, at least on Sabayon Linux. It needs some plugins provided
> by the kdm package which is why it crashes repeatedly.
> 
> Just installing kdm made screenlocking work for me. There's a related KDE
> bug https://bugs.kde.org/show_bug.cgi?id=314901 and a related Sabayon bug
> https://bugs.sabayon.org/show_bug.cgi?id=4235

I can confirm this on sabayon. Installed kdm and everything worked as expected.
Comment 31 Steven Franzen 2014-02-26 15:35:56 UTC
(In reply to comment #21)
> QtCurve confirmed to have the problem when in QtCurve's config dialog, under
> Opacity the Windows opacity percent is less than 100%. 
>     Fix: under Applications, ensure that kscreenlocker_greet (in addition to
> kscreenlocker) is included in the No background opacity list.

Confirmed that the issue is present on KDE 4.12.2 with QtCurve:
Name        : qtcurve-kde4
Arch        : x86_64
Version     : 1.8.14
Release     : 3.fc20 

I had to add kscreenlocker_greet to both the opacity and gradient exceptions for QtCurve in order to get the normal greeter.

Is this an issue that can be fixed within KDE, or should it also be filed against QtCurve/Oxygen Transparent/Bespin?
Comment 32 Yichao Yu 2014-02-26 15:40:36 UTC
The issue should already be fixed in QtCurve.
Comment 33 Thomas Lübking 2014-02-26 15:43:48 UTC
As in Bespin.
The locker could (and probably should) however be hardened against WId changes, since they can happen for other reasons as well (though most prominently altering the colortable, oc.)
Comment 34 Steven Franzen 2014-02-26 16:47:41 UTC
(In reply to comment #32)
> The issue should already be fixed in QtCurve.

Ah, cheers for the heads up; didn't realize you are the current maintainer of QtCurve ;). Removed the packaged version, installed the latest git version and was able to safely remove kscreenlocker_greet from the exceptions. The screen locker is drawn properly.
Comment 35 Klaus Fischer 2014-03-12 10:11:11 UTC
Is there a more verbose explanation of how to get rid of this problem when you experience it on a machine. It seems that it depends on the graphics card or some other issue. I am using 3 machines running kubuntu 13.10 running KDE 11.4.5 and only one of these machines seems to have this problem. I do not have the time to install updated packages from some repositories I don't know about and would be glad if there was a fix distributed by the standard update mechanism.

Thanks for your support.
Comment 36 Martin Flöser 2015-01-23 11:15:39 UTC
In summary it looks to me like this issue is fixed:
* bespin: fixed
* QtCurve: fixed
* oxygen-tranparent: fixed

As the problem doesn't occur with the default widget style as shipped by Plasma I'd say that there is nothing which we could do in addition.