Linux – umount: /filesystem: device is busy. No processes found using lsof and fuser

root@linux:~ # df -hP | grep SCR
/dev/mapper/vgSAPlocal-lv_sapmnt_SCR 15G 2.0G 12G 15% /sapmnt/SCR
scsscr:/export/sapmnt/SCR/exe 4.2G 3.5G 473M 89% /sapmnt/SCR/exe
scsscr:/export/sapmnt/SCR/global 4.2G 362M 3.6G 9% /sapmnt/SCR/global
scsscr:/export/sapmnt/SCR/profile 2.0G 3.0M 1.9G 1% /sapmnt/SCR/profile

I unmounted the filesystems under /sapmnt/SCR

root@linux:~ # umount /sapmnt/SCR/exe /sapmnt/SCR/global /sapmnt/SCR/profile
root@linux:~ #

But I was unable to unmount /sapmnt/SCR

root@linux:~ # umount /sapmnt/SCR
umount: /sapmnt/SCR: device is busy.
(In some cases useful info about processes that use
the device is found by lsof(8) or fuser(1))

After using fuser and lsof, it didn’t find any processes.
I was able to unmount it after restarting the autofs service

root@linux:~ # service autofs restart
Stopping automount: [ OK ]
Starting automount: [ OK ]