df reports a lot of none existing mount point

edit

My file /etc/fstab looks like this:

/dev/mapper/VgData-lv_data /storage                 ext4    defaults        1 2
/dev/mapper/VgData-lv_backup /backup                 ext4    defaults        1 2
/dev/mapper/VolGroup-lv_root /                       ext4    defaults        1 1
UUID=ab20316d-29ec-4f65-8984-a0392fed2386 /boot                   ext4    defaults        1 2
/dev/mapper/VolGroup-lv_swap swap                    swap    defaults        0 0

But when I run "df" I get in addition a lot of line with error "No such file or directory" (see below). How do I clean up this mess? It has no consequences but it should not be like that. I have been googled a lot but with no luck. Thanks.

/bin/df: `/tmp/systemd-namespace-JYZMQL/root': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/dev': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/dev/pts': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/dev/shm': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/dev/mqueue': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/dev/hugepages': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/proc/fs/nfsd': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/sys': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/sys/fs/cgroup': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/sys/fs/cgroup/systemd': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/sys/fs/cgroup/cpuset': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/sys/fs/cgroup/cpu,cpuacct': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/sys/fs/cgroup/memory': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/sys/fs/cgroup/devices': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/sys/fs/cgroup/freezer': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/sys/fs/cgroup/net_cls': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/sys/fs/cgroup/blkio': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/sys/fs/cgroup/perf_event': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/sys/kernel/security': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/sys/kernel/debug': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/sys/kernel/config': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/run': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/media': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/var/lib/nfs/rpc_pipefs': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/boot': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/backup': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/storage': No such file or directory
/bin/df: `/tmp/systemd-namespace-JYZMQL/root/tmp': No such file or directory