Re: [PATCH 3/4] virdevmapper: Don't use libdevmapper to obtain dependencies

On Tue, Aug 04, 2020 at 11:39 PM +0200, Andrea Bolognani <abologna(a)redhat.com&gt; wrote: > This patch broke libvirt in Debian for certain setups. > > With AppArmor enabled (the default), the error is > > $ virsh start cirros > error: Failed to start domain cirros > error: internal error: Process exited prior to exec: libvirt: > error : Cannot delete directory '/run/libvirt/qemu/1-cirros.dev': > Device or resource busy > > If I disable AppArmor by passing security='' on the kernel command > line, the error message changes to > > $ virsh start cirros > error: Failed to start domain cirros > error: internal error: Process exited prior to exec: libvirt: > QEMU Driver error : Unable to get devmapper targets for > /var/lib/libvirt/images/cirros.qcow2: Success > > An effective workaround is to set namespaces=[] in qemu.conf, but > that's of course not something that we want users doing :) > > The underlying issue seems to be caused by the fact that, on a Debian > installation that uses plain partitions instead of LVM, /proc/devices > doesn't contain an entry for device-mapper right after boot, which... > ... this code expects. > > Running > > $ sudo dmsetup info > No devices found We see the same problem as mentioned by Andrea. The host kernel configuration used: … CONFIG_BLK_DEV_DM_BUILTIN=y CONFIG_BLK_DEV_DM=m … As soon as we load the kernel module ‘dm-mod‘ everything works because then ‘device-mapper‘ is listed in /proc/devices.