[libvirt-users] Ubuntu 14.04 LTS KVM issue: setdev ioctl failed on blockpoll: Device or resource busy

Hi, I ran into a strange issue when I brought up my virtual device on KVM after I upgraded my box to Ubuntu 14.04 LTS. My virtual device has two disks: one boot disk and one empty disk. It was able to boot up, but ioctl on the second disk image failed with error messages like: setdev ioctl failed on blockpoll: Device or resource busy Any thoughts what happened. It worked fine with Ubuntu 12. Our virtual device called open_bdev_exclusive and failed. AppArmor seems not the problem because I saw the same issue with app armor disabled. Thanks.