Pixels on screen when copying large files in 14.04

[Peter Taps]

I have reasonably good experience in installing and using Ubuntu. I have installed various releases of Ubuntu on hundreds of machines so far. There is a subtle problem in Ubuntu 14.04 kernel. It manifests itself when copying large files. The screen gets filled with colored pixels. The source file could either come from a mounted external disk or via sftp.

The problem happens only with large files but not with smaller sizes. The file I am testing with is about 5G in size.

After many trials, I have reduced the problem to this basic setup:

1. Install Ubuntu 14.04 Server 64-bit through standard installation. No need to install any additional package. Reboot and login. You will be placed in a console window.
2. sudo mount /dev/sdc2 ~/myextdrive
3. cp ~/myextdrive/mylargefile.mp4 ~/Temp/

After a couple of seconds during the copy operation, the screen gets completely filled with colored pixels.

The system is still alive. After about five minutes, I can do a "sudo reboot" (although I don't see what I am typing).

To ensure that the problem is only with 14.04, I formatted the disk and installed 13.04 Server on the disk and tried steps 2 and 3. It works with no problems.

Next, I ran "do-release-upgrade." This eventually upgraded to 13.10. I tried steps 2 and 3 once again. No problems.

Next, I ran "apt-get update, upgrade, dist-upgrade, and do-release-upgrade. This time the system was upgraded to 14.04. I tried steps 2 and 3 once again. The problem reappears.

I tried to run ubuntu-bug but there is no crash report that has been generated. If there is any log information that you would like to see, please let me know and I can send it.

Regards,
Peter

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Freenode.

To change the source package that this bug is filed about visit https://bugs.launchpad.net/ubuntu/+bug/1369374/+editstatus and add the package name in the text box next to the word Package.

[This is an automated message. I apologize if it reached you inappropriately; please just reply to this message indicating so.]

[Peter Taps (ptrtap)]

I tried to add linux-image-3.13.0-35-generic as the package. However, the edit status link does not work anymore. Thanks.

[Peter Taps (ptrtap)]

I see if this is a problem with mode setting, I also added nomodeset to grub. Makes no difference.

[penalvch (penalvch)]

Peter Taps, thank you for taking the time to report this bug and helping to make Ubuntu better. Please execute the following command only once, as it will automatically gather debugging information, in a terminal:
apport-collect 1369374

When reporting bugs in the future please use apport by using 'ubuntu-bug' and the name of the package affected. You can learn more about this functionality at https://wiki.ubuntu.com/ReportingBugs.

[Launchpad Janitor (janitor)]

[Expired for linux (Ubuntu) because there has been no activity for 60 days.]