I confirm it's fixed in 3.19.0-031900, it's still broken in 14.04.02 LTS with kernel 3.16.0-30-generic. With further testing, whatever is broken was fixed between 3.18rc2 and 3.18rc3 kernels:
Broken: 3.18.0-031800rc2 [1] Fixed: 3.18.0-031800rc3 [2] The number of commits between these two is rather high making it difficult to easily spot what may have fixed the bug; the diff from rc2 to rc3 is 621,132 bytes. The test setup is easy - using VirtualBox, create a new VM accepting all defaults. Install 14.04.02 LTS using all defaults, all very generic. In all broken cases specifying "noautogroup" on the kernel params bypasses the bug. I was able to record a MKV @100fps and extract two PNG files showing the best I can capture; it goes by so fast that even at 100fps I can't capture a few missing lines. [1] http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.18-rc2-vivid/ [2] http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.18-rc3-vivid/ ** Attachment added: "screencap of crash, 1/2" https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1422016/+attachment/4325063/+files/p2146.png -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1422016 Title: Kernel panic during system boot with sched_autogroup_enabled = 0 Status in linux package in Ubuntu: Confirmed Bug description: # lsb_release -rd Description: Ubuntu 14.04.1 LTS Release: 14.04 # uname -a Linux napa 3.13.0-32-generic #57-Ubuntu SMP Tue Jul 15 03:51:08 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux A kernel panic occurs while disabling the automatic task group creation within /etc/sysctl.conf using "kernel.sched_autogroup_enabled = 0". After adding the "noautogroup" kernel parameter to GRUB, the system will boot without issue. I have attached a screen shot of the stack trace as I was unable to capture the stack trace using netconsole, linux-crashdump, and /var/log/kern.log. Oddly enough, while trying one last approach (serial console) to capture the full trace within virtual box using a host pipe and setting console=ttyS0, the system booted without issue and disabled automatic task group creation. According to https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1055222, a fix for the issue has hit the Precise kernel and should be released in 3.2.0-36. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1422016/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
