Need some assistance diagnosing a kded/plasma crash on logon
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Registered Member 
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Hi All,
I'm doing some testing with the Kubuntu 14.04 beta, and I'm attempting to diagnose why plasma and/or the kde daemon crashes on logon when authenticating with ldap. The situation: We use a custom LiveCD based configuration for deployment of our desktops[1], based on ubuntu and it's casper initramfs. Therefore this is being executed in a 'live' environment. I've configured ldap and pam to allow authentication/authorisation against our ldap servers, and this configuration works fine on an installed environment. However, when I deploy this same configuration in a live environment, KDE exhibits some unusual behaviour - after the ksplash loads, it presents me with a standard wallpaper, a blank panel, and an error message indicating that either the KDE Daemon or the Plasma Desktop Shell have segfaulted[2] I can click on the developer information tab, but the heading at the top is particularly accurate when it says "The generated crash information is probably not useful". Ive attached the generated log anyway[3] I can replicate this error on either a custom master of my own, or on the vanilla kubuntu 14.04 beta1 release. Now, I fully realise that I am working on a beta distro release, in an unusual environment. Neither of those things can be changed within the scope of this project at this point so, what I need is some direction on how I can best go about narrowing down/diagnosing the issue and reporting/potentially patching it. Thanks for any assistance  Nuts and bolts: Distro: (k)ubuntu 14.04 KDE: 4.12.2 (dpkg reports 4:4.12.3-0ubuntu1 - on a build from today) [1]: http://dot.kde.org/2014/02/18/kde-software-down-under [2]: http://i4.photobucket.com/albums/y131/c ... a64531.png [3]:
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Administrator
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This appears to be a crash in the Plasma NM applet - do your systems manage their connectivity using NetworkManager?
In terms of getting a better backtrace, please install debugging symbols for qt, kdelibs, libnm-qt and plasma-nm.
KDE Sysadmin
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Registered Member
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Thanks for the reply
Yes they do use network manager (at least the vanilla kubuntu does, and I try to keep as close to their package manifest as I can). I couldn't find all the debugging packages you mentioned, so I've installed the following packages: libqt4-dbg libqt5v8-5-dbg kdelibs5-dbg kde-workspace-dbg network-manager-dbg The results below are for the vanilla kubuntu beta1 livecd, for whatever reason the mirrors for my up-to-date build are super slow, so I won't have results for you before I finish work for the week. I figured some results were better than none  Also, some patterns have emerged: New users logging on without an existing profile get a kded crash AND a plasma crash Logging on with a user who's profile has been previously created only gets a kded crash Note: Profiles are created with the pam mkhomedir.so module The results below are from a first time logon, with both kded and plasma crashes KDE Daemon trace:
Plasma trace:
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Administrator
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I've checked with the developers - and they've only seen this crash when Qt 4 and Qt 5 libraries are intermixed.
Please verify the Kubuntu Live images are constituted from the correct packages.
KDE Sysadmin
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Registered Member
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[quote="bcooksley"]I've checked with the developers - and they've only seen this crash when Qt 4 and Qt 5 libraries are intermixed.
Please verify the Kubuntu Live images are constituted from the correct packages.[/quote] According to the package manifests, neither my builds or the vanilla kubuntu have any Qt 5 libraries, so I'm not sure how to verify what's "correct" - how do you recommend I do this? |
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Administrator
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Please provide the output of the following commands:
KDE Sysadmin
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Registered Member
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Sorry for the late reply, for some reason I didn't get a notification of your post -
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Registered Member
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Hi bcooksley, did the above output assist at all?
Ubuntu Trusty has moved to final beta so there's a little bit of pressure to work out why this is happening -
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Registered Member
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I realise there are a lot of similar bugs. This is specifically reproducible when I enable LDAP authentication on a casper booted live environment. I also realise that it's a fairly non-specific symptom to report, so I'm trying to narrow it down further if possible (hence the q's) |
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Registered Member
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Thanks for looking into it - that 331151 link was very useful. I did a rebuild, KDE has upgraded and this patch looks like it's been incorporated, because I'm no longer getting the plasma crash. However I'm still seeing a kded crash (gdb log attached) on every logon, regardless if the profile has been created or not. [edit] I take it back, plasma crash is still happening on first logon (maybe not consistently now) -
[/edit] I'm not sure what I should be seeing in the other two bugs. They're old (~2010) and resolved as fixed or invalid, but I'm operating on current packages here.
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Registered Member
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I've decided to try and get it moving in launchpad since I suspect it's related to the casper initramfs environment -
https://bugs.launchpad.net/ubuntu/+sour ... ug/1300515 |
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Administrator
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Can you see if kded4 manages to output anything into ~/.xsession-errors before it crashes?
Based on the trace I strongly suspect that Qt itself is causing the application to exit - and this notice will only be posted in the log.
KDE Sysadmin
[img]content/bcooksley_sig.png[/img] |
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They're all the same backtrace and refer to LDAP. It's extremely unlikely that there's a such old bug in QDBusPendingReply, thus the actual bug is probably not fixed, might be related to thread and timing and is likely triggered by a not holding prerequisite, regarding either dbus, networkmanager or qsharedmemory. I doubt that the bug you're encountering is somehow new but the very same as all other bugs with the very same backtrace and all fixes have just been fixes on symptoms. |
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