pct fstrim - can't umount lvm disk

[achirkov]

Hi!
Today i run command pct fstrim 100 on disable lxc container and my ssh connection was disconnected.
After reconnect i try fstrim and get error:

mount: /var/lib/lxc/100/rootfs: /dev/mapper/vg0-vm--100--disk--0 already mounted on /var/lib/lxc/100/rootfs.

Ok, trying umount:

# umount -f /var/lib/lxc/100/rootfs/
umount: /var/lib/lxc/100/rootfs: target is busy.

How i can umount disk without restart proxmox host?

 

[achirkov]

After hour awaiting umount -f just worked.