Bug 348053

Summary:	Screen locker freeze results into inaccessible session
Product:	[Unmaintained] kscreenlocker	Reporter:	Ancoron <ancoron.luciferis>
Component:	general	Assignee:	David Edmundson <kde>
Status:	RESOLVED UPSTREAM
Severity:	crash	CC:	bshah, mgraesslin, ndbecker2, plasma-bugs-null
Priority:	NOR
Version First Reported In:	unspecified
Target Milestone:	---
Platform:	Ubuntu
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Attachments:	Output of "ps auxnf" at the time of the freeze gdb all threads backtraces from plasmashell

Description Ancoron 2015-05-21 10:33:04 UTC

Occasionally, I experience complete UI freezes as described already in other bug reports which are either only temporary by itself or can be overcome with a "workaround" of hitting "Alt+Tab" to activate the task switcher.

However, if such a non-temporary freeze happens while the system is locked, the task switcher obviously cannot be activated which then results into an inaccessible session.

Though, switching to another console by keyboard works and the session an be killed. Nevertheless, in the cases I observed I always see a lot of Dolphin processes and others which are in Zombie state.

Reproducible: Always

Comment 1 Ancoron 2015-05-21 10:34:10 UTC

Created attachment 92759 [details]
Output of "ps auxnf" at the time of the freeze

Comment 2 Ancoron 2015-05-21 10:36:43 UTC

Created attachment 92760 [details]
gdb all threads backtraces from plasmashell

As far as I can see, the backtraces of the plasmashell process threads indicate it is blocked in XCB event reading.

Comment 3 Ancoron 2015-05-21 10:39:42 UTC

I also see a lot of these in the .xsession-errors file although I don't know if they are related or not:

warning - 0xaa0170 - kwin(3883)/(default) unknown: QXcbConnection: XCB error: 3 (BadWindow), sequence: 11425, resource id: 113250842, major code: 18 (ChangeProperty), minor code: 0

Comment 4 Neal Becker 2015-06-05 13:01:23 UTC

This might be the same bug I see, but mine is 100% reproducible.

I have 2 screens - 1 external monitor.

1. start kde with 2 monitors
2. close laptop lid to go to sleep
3. disconnect external monitor
4. open lid

Now (assuming you have lock-on-resume) I have a lock screen, but I can't enter the password.  Nothing happens when I hit keys.  Mouse cursor is responsive, but I can't do anything else.

Comment 5 Martin Flöser 2015-12-15 17:15:33 UTC

#2  0x00007f37bd951b72 in _xcb_conn_wait (c=c@entry=0x1d9d920, cond=cond@entry=0x7fff01df9f10, vector=vector@entry=0x0, count=count@entry=0x0) at ../../src/xcb_conn.c:447
#3  0x00007f37bd9533ff in wait_for_reply (c=c@entry=0x1d9d920, request=142151, e=e@entry=0x0) at ../../src/xcb_in.c:490
#4  0x00007f37bd953512 in xcb_wait_for_reply (c=c@entry=0x1d9d920, request=142151, e=e@entry=0x0) at ../../src/xcb_in.c:520
#5  0x00007f37bd956cc5 in xcb_get_geometry_reply (c=c@entry=0x1d9d920, cookie=..., e=e@entry=0x0) at xproto.c:3081
#6  0x00007f37b71c1422 in dri3_get_buffers (driDrawable=<optimized out>, loaderPrivate=0x1db8e60)
    at ../../../../src/glx/dri3_glx.c:1069
#7  0x00007f37b71c1422 in dri3_get_buffers (driDrawable=<optimized out>, format=4099, stamp=0x5e169b0, loaderPrivate=0x1db8e60, buffer_mask=1, buffers=0x7fff01dfa0e0) at ../../../../src/glx/dri3_glx.c:1431

blocked in the OpenGL driver :-(

The problem indicates dri3 being used. That was still rather broken a few months ago. I assume this issue is resolved nowadays. If not please reopen.

Comment 6 Ancoron 2015-12-15 17:52:10 UTC

For me, the issue seems to have been resolved by itself. Thanx anyway for checking back. :-)