Crash on screen power save

[Timo Jyrinki]

Continuation to bug #1548766 to consider another upstream fix from https://codereview.qt-project.org/#/c/138681/

The fix could affect both monitor power saving or attaching/detaching cycles.

[Timo Jyrinki (timo-jyrinki)]

Could you test ppa:ci-train-ppa-service/landing-051 (you should get qtbase packages versioned 5.5.1+dfsg-14ubuntu3~xenial1~test1) and report back any differences in behavior on your setup?

The list of included patches can be seen at http://anonscm.debian.org/cgit/pkg-kde/qt/qtbase.git/tree/debian/patches/series?h=ubuntu - the name of the patch usually matches the commit message at http://code.qt.io/cgit/qt/qtbase.git/log/src/plugins/platforms/xcb

[Ryan (carbonfreeze)]

I'm seeing similar behavior to the previous PPA, when the screens are disconnected the panel fails to resize, and when the screens are reconnected plasma segfaults. Note that in my configuration, the internal display is disabled by kscreen to allow both external monitors to activate.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Launchpad Janitor (janitor)]

This bug was fixed in the package qtbase-opensource-src - 5.5.1+dfsg-14ubuntu3

---------------
qtbase-opensource-src (5.5.1+dfsg-14ubuntu3) xenial; urgency=medium

  * debian/patches/Xcb-fix-crash-on-screen-power-save.patch:
    - Fix additional cases where crash could occur on monitor disconnections
      or power save. (LP: #1551122)
  * Build with C.UTF-8 locale to (LP: #1551145) and re-enable tests (LP: #1548686)

 -- Timo Jyrinki <email address hidden> Wed, 02 Mar 2016 10:28:04 +0000

[Shawn Rutledge (shawn-t-rutledge)]

Updated to 5.5.1+dfsg-14ubuntu3. It's not enough to prevent Plasma from crashing if I disconnect/reconnect both monitors simultaneously with my script.

#!/bin/sh
restore=`unxrandr`
outputs=`xrandr | grep -i "^\\w" | grep connected | cut -d' ' -f1`
alloff="xrandr"
for o in $outputs
do
        alloff="$alloff --output $o --off"
done
echo $alloff
echo $restore
$alloff
sleep 2
$restore

But at least applications tend to survive, and plasma restarts itself.

[Shawn Rutledge (shawn-t-rutledge)]

likewise with 5.5.1+dfsg-15ubuntu1

[Timo Jyrinki (timo-jyrinki)]

Thanks for testing both of the new versions, at least it does not regress from the 5.5.1+dfsg14ubuntu2. Potentially the new patch helps in some situations as it did for Paul who submitted it to 5.6.

[Mike Butash (michael-butash)]

I'm currently on 5.5.1+dfsg-16ubuntu7, which should be newer and include these, no?

I found this digging into why xenial's kde5 plasma shell and all kde apps keep freaking when my 4k displays go away. Like others, I use big 4k tv's (3x of them) that give no signal when they power down, so the displays go away entirely with variable results.

Harassing the kwin guys led me here as deeper qt bugs, but still seems present as of stated version.

[Timo Jyrinki (timo-jyrinki)]

Upstream has struggled for a long time with these problems, and we have plenty of backported fixes from Qt 5.6 branch in our 16.04's Qt 5.5. Sadly they don't fix all issues still.

The next upload is already being prepared and is at https://launchpad.net/~ci-train-ppa-service/+archive/ubuntu/landing-016 if you want to test and report back if there is any change for you. It has yet another two patches to these issues and some other patches that are not related.

So you could test it with:
sudo apt-add-repository ppa:ci-train-ppa-service/landing-016
sudo apt update
sudo apt dist-upgrade

And later downgrade back (please do, to remove the PPA from system, the contents will change):
sudo apt install ppa-purge
sudo ppa-purge ppa:ci-train-ppa-service/landing-016

[Shawn Rutledge (shawn-t-rutledge)]

Maybe it's a little better, but not there yet. I have two monitors attached. I tried running Creator and Assistant, then running my script which uses xrandr to remove and re-add the displays. I tried this first in a Plasma session. When the screens came back to life I had only a black screen (kwin still running), no applications. Killed X and logged in again with OpenBox, and ran Creator and Assistant again. Kerchunk script, and this time Creator crashed but Assistant survived. Ran Creator again, used arandr to disable one monitor. Ran the script again, and again Creator crashed while Assistant survived. Tried again with the qopenglwindow example; that survives the kerchunk script too.

Maybe if I could have a look at which patches you have cherry-picked on top of 5.5, could figure out what is still missing.

[Shawn Rutledge (shawn-t-rutledge)]

BTW how soon will Ubuntu upgrade to Qt 5.6?

[Thomas Weissel (xapient)]

i use this repo (kde neon) http://archive.neon.kde.org/tmp/testing
which delivers an up2date plasma 5.6.4 and Qt 5.6 and the bug is still there.. sometimes the display configurations is messed up and if i disconnect (sleep or power off) one of my screens, plasma is gone :(

[Thomas Weissel (xapient)]

sorry... the repository is offline by now so i tried this one

deb http://archive.neon.kde.org/dev/unstable xenial main

kde 5.6.99
qt 5.6

status report:

the bug is still here but in a weird way.. plasma starts with one screen black.. deactivating/activating it in kscreen systemsettings brings it back to life..

powermanagment sleep "killed" the other display (black) but panel and rightclick remained active..
i could change the wallpaper and revived it by that action..

????
so it seems the new plasma is not segfaulting anymore but still doesn't know how to handle the situation

[removed (3yppo85ezb14clb5)]

Affects me as well, particularly during shutdown. When I try to shutdown, the screen goes completely black except for the Dr.Konqui windoe in the middle, complaining that ksmserver has segfaulted. If I try to continue with the report the window closes but the computer never shuts down, so I have to hold the power button. The same thing happens if I don't report it. It als segfaults when I unlock the computer after it goes to sleep, but that isn't as bad because I can restart it from Tilda.vThis wasn't a problem until recently, after many programs were updated all at once (I assume qt was in there somewhere). Assuming this update was supposed to be a fix, it didn't work.

[Timo Jyrinki (timo-jyrinki)]

@Shawn: http://anonscm.debian.org/cgit/pkg-kde/qt/qtbase.git/tree/debian/patches?h=ubuntu is currently about Qt 5.5. It has most of the xcb screen related patches backported one way or another (sometimes a bit tricky) from 5.6, but as mentioned here and elsewhere on the net also 5.6 users suffer from related problems.

Qt 5.6.1 is planned to be landed to Ubuntu 16.10, but 16.04 LTS and the bulk of the desktop users will remain on Qt 5.5 so any additional 5.5 patches will be welcome in the future too.