[root@ip-172-31-67-44 ~]# df -PH
Filesystem      Size  Used Avail Use% Mounted on
devtmpfs        4.2M     0  4.2M   0% /dev
tmpfs           4.0G     0  4.0G   0% /dev/shm
tmpfs           1.6G  9.0M  1.6G   1% /run
/dev/nvme0n1p4  9.9G  1.5G  8.4G  16% /oldroot
none            4.0G  1.4G  2.6G  35% /
tmpfs           788M     0  788M   0% /run/user/1000

[root@ip-172-31-67-44 ~]# systemctl daemon-reexec

[root@ip-172-31-67-44 ~]# fuser -vmk /oldroot
                     USER        PID ACCESS COMMAND
/oldroot:            root     kernel mount /oldroot
                     root        552 ...e. systemd-journal
                     root        569 .rce. systemd-udevd
                     root        643 .rce. auditd
                     dbus        669 .rce. dbus-broker-lau
                     dbus        673 .rce. dbus-broker
                     root        676 .rce. irqbalance
                     root        678 .rce. systemd-logind
                     chrony      685 .rce. chronyd
                     root        714 .rce. NetworkManager
                     root        726 F..e. tuned
                     root        727 ...e. rhsmcertd
                     polkitd     991 ...e. polkitd
                     root       1046 .rce. rsyslogd
                     root       1049 ...e. crond
                     root       1050 ...e. agetty
                     root       1051 ...e. agetty
                     ec2-user   4252 ...e. (sd-pam

[root@ip-172-31-67-44 ~]# sleep 15

[root@ip-172-31-67-44 ~]# fuser -vm /oldroot
                     USER        PID ACCESS COMMAND
/oldroot:            root     kernel mount /oldroot

[root@ip-172-31-67-44 ~]# umount /oldroot

[root@ip-172-31-67-44 ~]# grep nvme /proc/mounts

[root@ip-172-31-67-44 ~]# df -PH
Filesystem      Size  Used Avail Use% Mounted on
devtmpfs        4.2M     0  4.2M   0% /dev
tmpfs           4.0G     0  4.0G   0% /dev/shm
tmpfs           1.6G   18M  1.6G   2% /run
none            4.0G  1.4G  2.6G  35% /
tmpfs           788M     0  788M   0% /run/user/1000

[root@ip-172-31-67-44 ~]# blkid
/dev/nvme0n1p4: LABEL="root" UUID="8b4a4ce6-cc11-42e3-afc4-bbb13f950d40" TYPE="xfs" PARTUUID="6264d520-3fb9-423f-8ab8-7a0a8e3d3562"
/dev/nvme0n1p3: LABEL="boot" UUID="af92dd76-6f1f-47ed-a0b7-126b19b67bd4" TYPE="xfs" PARTUUID="cb07c243-bc44-4717-853e-28852021225b"
/dev/nvme0n1p1: PARTUUID="fac7f1fb-3e8d-4137-a512-961de09a5549"
/dev/nvme0n1p2: SEC_TYPE="msdos" UUID="7B77-95E7" TYPE="vfat" PARTUUID="68b2905b-df3e-4fb3-80fa-49d1e773aa33"

[root@ip-172-31-67-44 ~]# lsblk
NAME        MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTS
nvme0n1     259:0    0   10G  0 disk
├─nvme0n1p1 259:1    0    1M  0 part
├─nvme0n1p2 259:2    0  200M  0 part
├─nvme0n1p3 259:3    0  600M  0 part
└─nvme0n1p4 259:4    0  9.2G  0 part

[root@ip-172-31-67-44 ~]#