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Help in locating source of Qt 5.6.0 assertion crash

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  • E Offline
    E Offline
    eureka
    wrote on last edited by
    #1

    I have reported a crash when running browser examples in Qt 5.6.0 on Ubuntu 14.04.
    The report is here ..

    https://forum.qt.io/topic/65459/qtwebenginewidgets-example-crash-report

    But no replies so far.
    Can anyone help to troubleshoot this pattern in Qt Creator Application Output
    ../../nouveau/pushbuf.c:726: nouveau_pushbuf_data: Assertion `kref' failed.
    which appears just before the crash occurs?

    So far in searching around I've found a few bug reports (google search the above pattern) .. but no solution.

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    • E Offline
      E Offline
      eureka
      wrote on last edited by eureka
      #2

      I have really hit a dead end with this Assertion `kref' failed report which I see when running Qt 5.6.0 example demobrowser.

      In Qt 5.6 Creator I tried starting a Debug session

      (1) Loaded project demobrowser into Qt Creator

      (2) Debug > Start Debugging

      (3) demobrowser builds with debug information seen.

      (4) Popup message box at end ...

      The inferior stopped because it received a signal from the operating system.

      Signal name : SIGABRT
      Signal meaning : Aborted

      (5) Looking at Qt Creator debug information panels

      Disassembler refers to __kernel_vsyscall
      Threads refers to #22 Chrome InProcGP Stopped: Aborted (Signal SIGABRT)

      (6) The full debugger dump is pasted into pastebin guest account

      http://pastebin.com/gi07NLQU

      The summary is seen at line 931 ...

      demobrowser: ../../nouveau/pushbuf.c:726: nouveau_pushbuf_data: Assertion `kref' failed.

      (7) I cannot decipher debug dumps so I'm hoping that some experienced developer can offer a clue on how to troubleshoot this crash.

      It seems to point to nouveau/mesa. But I'm guessing.

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      • SGaistS Offline
        SGaistS Offline
        SGaist
        Lifetime Qt Champion
        wrote on last edited by SGaist
        #3

        Hi,

        Looks like something lower level between web engine and nouveau. You should try to contact both of them folks.

        You might also want to bring that to the QtWebEngine mailing list You'll find there QtWebengine developers/maintainers. This forum is more user oriented.

        Interested in AI ? www.idiap.ch
        Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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        • E Offline
          E Offline
          eureka
          wrote on last edited by
          #4

          @SGaist

          Thanks for that tip. I'll head to that mailing list to research further.

          I did find today a few users who report similar problems with QtWebEngine.

          Here is one .. http://thankcoder.com/questions/k1xxt/qtwebengine-demo-application-crashes

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          • E Offline
            E Offline
            eureka
            wrote on last edited by
            #5

            SOLVED

            I picked up a clue from the owner of the PPA repo.

            The problem was in an open source NVIDIA driver I had installed. X.Org.
            This was seen in Ubuntu Software Centre > Software Sources > Additional Drivers
            I dropped to another NVIDIA driver (proprietary, tested).

            http://askubuntu.com/questions/498401/installing-nvidia-drivers-to-14-04

            Rebooted.

            I was able to run Qt 5.6.0 demobrowser without hitting previous nouveau crash.

            I may have to try different proprierary drivers but moving away from X.Org open source driver has removed the crash conditions.

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