Red Hat Bugzilla – Bug 240248
kvm produces BUG warning when taking a CPU offline
Last modified: 2008-08-02 19:40:36 EDT
Description of problem: With the KVM module loaded, I took a CPU core offline, and got a BUG message. No VMs were created or running at the time. Version-Release number of selected component (if applicable): kernel-2.6.21-1.3116.fc7 kvm-19-2 How reproducible: Unable to reproduce, thus far Steps to Reproduce: 1. /etc/init.d/libvirtd start 2. echo 0 > /sys/devices/system/cpu/cpu1/online Actual results: See BUG message in dmesg (attached) Additional info: http://smolt.fedoraproject.org/show?UUID=492900d9-5ee0-441c-9792-fc2ecc86aa5d
Created attachment 154788 [details] dmesg BUG
After trying a few more times, I was able to reproduce this with the same steps -- but it is quite random, sometimes working, sometimes erroring. I also tried bringing the CPU back online after this error occurs, which leads to a soft lockup on CPU #1. (See attached file. Note: this dump was captured manually from a photo, may contain typos.)
Created attachment 154789 [details] crash when bringing cpu back online
Unfortunately this requires a change to the kernel core. I'll try to get a fix for the next upstream kvm release.
2.6.23-rc1 has cpu hotplug working with kvm. It should be easy to backport the patches (the same patches needed for suspend).
Based on the date this bug was created, it appears to have been reported against rawhide during the development of a Fedora release that is no longer maintained. In order to refocus our efforts as a project we are flagging all of the open bugs for releases which are no longer maintained. If this bug remains in NEEDINFO thirty (30) days from now, we will automatically close it. If you can reproduce this bug in a maintained Fedora version (7, 8, or rawhide), please change this bug to the respective version and change the status to ASSIGNED. (If you're unable to change the bug's version or status, add a comment to the bug and someone will change it for you.) Thanks for your help, and we apologize again that we haven't handled these issues to this point. The process we're following is outlined here: http://fedoraproject.org/wiki/BugZappers/F9CleanUp We will be following the process here: http://fedoraproject.org/wiki/BugZappers/HouseKeeping to ensure this doesn't happen again.