I've had a number of lockups in the last 2 days since upgrading to Trusty and trying to run a VM under kvm which look to match this issue.
System appears to become unresponsive/hang with what looks like some kind of I/O lockup, cannot ls in a terminal etc before eventually display freezes. syslog shows kernel spew related to soft lockup after this point though. The issue appeared to coincide with a period of high disk I/O within the guest on both occasions. I'll look to reproduce on a less active guest outside of working day. This occured on a 64 bit system: lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu Trusty Tahr (development branch) Release: 14.04 Codename: trusty uname -a Linux moon127-pcsubu 3.13.0-12-generic #32-Ubuntu SMP Fri Feb 21 17:45:10 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux ** Attachment added: "syslog/kernel log of lockup" https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1268906/+attachment/3999385/+files/soft-lockup-syslog.txt -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1268906 Title: cpu soft lockup running kvm To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1268906/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs