You have been subscribed to a public bug: When installing qemu-kvm on a VM, KSM is enabled.
I have encountered this problem in trusty:$ lsb_release -a Distributor ID: Ubuntu Description: Ubuntu 14.04.1 LTS Release: 14.04 Codename: trusty $ uname -a Linux juju-gema-machine-2 3.13.0-40-generic #69-Ubuntu SMP Thu Nov 13 17:53:56 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux The way to see the behaviour: 1) $ more /sys/kernel/mm/ksm/run 0 2) $ sudo apt-get install qemu-kvm 3) $ more /sys/kernel/mm/ksm/run 1 To see the soft lockups, deploy a cloud on a virtualised env like ctsstack, run tempest on it, the compute nodes of the virtualised deployment will eventually stop responding with (run tempest 2 times at least): 24096.072003] BUG: soft lockup - CPU#0 stuck for 23s! [qemu-system-x86:24791] [24124.072003] BUG: soft lockup - CPU#0 stuck for 23s! [qemu-system-x86:24791] [24152.072002] BUG: soft lockup - CPU#0 stuck for 22s! [qemu-system-x86:24791] [24180.072003] BUG: soft lockup - CPU#0 stuck for 22s! [qemu-system-x86:24791] [24208.072004] BUG: soft lockup - CPU#0 stuck for 22s! [qemu-system-x86:24791] [24236.072004] BUG: soft lockup - CPU#0 stuck for 22s! [qemu-system-x86:24791] [24264.072003] BUG: soft lockup - CPU#0 stuck for 22s! [qemu-system-x86:24791] I am not sure whether the problem is that we are enabling KSM on a VM or the problem is that nested KSM is not behaving properly. Either way I can easily reproduce, please contact me if you need further details. ** Affects: qemu-kvm (Ubuntu) Importance: Undecided Status: New ** Tags: cts -- qemu-kvm package enables KSM on VMs https://bugs.launchpad.net/bugs/1413540 You received this bug notification because you are a member of Ubuntu Server Team, which is subscribed to qemu-kvm in Ubuntu. -- Ubuntu-server-bugs mailing list Ubuntu-server-bugs@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-server-bugs