Comment 127 for bug 1679898

Hi,

We still experience this bug. We use Hyper-V 2012 and use Veeam to create VM backups (though this fact might be irrelevant). We upgraded our Ubuntu 14.04 to the latest xenial kernel (4.4.0-91) and still experience the VM hanging/freezing/stacktracing regularly directly after backup. Sometimes the server becomes unresponsive and shows the following error in the syslog: "Hyper-V VSS: VSS: freeze of /boot: Operation not supported" (after that it dies). The stacktrace included now did not crash the server, but it was definitely caused by the VM backup.

Some more info:
uname -a:

Linux SERVERNAME 4.4.0-91-generic #114~14.04.1-Ubuntu SMP Wed Aug 9 08:47:26 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

lsmod | grep 'hv_' :

hv_utils 28672 2
hv_storvsc 20480 260
ptp 20480 1 hv_utils
scsi_transport_fc 65536 1 hv_storvsc
hv_netvsc 40960 0
hv_vmbus 90112 6 hyperv_keyboard,hv_netvsc,hid_hyperv,hv_utils,hyperv_fb,hv_storvsc

dpkg --list | grep '4.4':

ii linux-cloud-tools-4.4.0-91-generic 4.4.0-91.114~14.04.1 amd64 Linux kernel version specific cloud tools for version 4.4.0-91
ii linux-cloud-tools-virtual-lts-xenial 4.4.0.91.75 amd64 This package will always depend on the latest minimal generic kernel cloud tools.
ii linux-generic-lts-xenial 4.4.0.91.75 amd64 Complete Generic Linux kernel and headers
ii linux-headers-4.4.0-91 4.4.0-91.114~14.04.1 all Header files related to Linux kernel version 4.4.0
ii linux-headers-4.4.0-91-generic 4.4.0-91.114~14.04.1 amd64 Linux kernel headers for version 4.4.0 on 64 bit x86 SMP
ii linux-headers-generic-lts-xenial 4.4.0.91.75 amd64 Generic Linux kernel headers
ii linux-image-4.4.0-91-generic 4.4.0-91.114~14.04.1 amd64 Linux kernel image for version 4.4.0 on 64 bit x86 SMP
ii linux-image-extra-4.4.0-91-generic 4.4.0-91.114~14.04.1 amd64 Linux kernel extra modules for version 4.4.0 on 64 bit x86 SMP
ii linux-image-generic-lts-xenial 4.4.0.91.75 amd64 Generic Linux kernel image
ii linux-lts-xenial-cloud-tools-4.4.0-91 4.4.0-91.114~14.04.1 amd64 Linux kernel version specific cloud tools for version 4.4.0-91
ii linux-lts-xenial-tools-4.4.0-91 4.4.0-91.114~14.04.1 amd64 Linux kernel version specific tools for version 4.4.0-91
ii linux-tools-4.4.0-91-generic 4.4.0-91.114~14.04.1 amd64 Linux kernel version specific tools for version 4.4.0-91
ii linux-tools-virtual-lts-xenial 4.4.0.91.75 amd64 This package will always depend on the latest minimal generic kernel tools.

I hope this issue can get fixed soon. Stop making backups is not really an option for us.