when we perform this ( on linux redhat 7.x)
umount /grop/sdc umount: /grop/sdc: target is busy. (In some cases useful info about processes that use the device is found by lsof(8) or fuser(1))
we can see that mount failed on busy
but when we do remount then ... remount is success as the following:
mount -o rw,remount /grop/sdc echo $? 0
so very interesting
dose remount use the option like ( umount -l ) ? what the diffrent between remount to umount/mount ?