[libvirt] Mount events are not propagated to namespaces

Dear list, while trying to fix a bug of mine, I've realized the mounts are not being propagated into qemu namespaces once domains are running. That is, imagine you have a domain running and then you plug in a flash disk, mount it into host, because you have a file there that you want to hotplug as a disk to your domain. You're not hotplugging the whole flash disk, but a file on it. Problem is, that the mount event of the flash disk is not propagated to qemu namespace even though the root is remounted as MS_SLAVE|MS_REC right after the namespace is created. After some digging. I am able to reproduce this even without libvirt at all: # mount --make-rshared / # mount | grep floppy <empty/> # unshare -m /bin/bash # mount --make-rslave / Now mount floppy from a different terminal: # mount /dev/sdb1 /mnt/floppy/ # mount | grep floppy /dev/sdb1 on /mnt/floppy type ext4 (rw,relatime,data=ordered) At this point, mount should have been propagated into namespace. Well, it isn't: # mount | grep floppy <empty/> Do you have any idea what I am doing wrong? We need this to work not only because of the example described above, but for a whole lot more cases. Michal