Comment 2 for bug 476072

So in version 16.04 is is the same thing.......
When i want to wirite some thing in the partition /dev/sda1 witch is mounted on /cdrom
ubuntu@ubuntu:~$ sudo mount|grep sda1
/dev/sda1 on /cdrom type vfat (ro,noatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro)
ubuntu@ubuntu:~$

witch it contains
ubuntu@ubuntu:~$ ls /cdrom
boot ldlinux.c32 preseed SmartClean.ini
casper ldlinux.sys README.diskdefines syslinux
dists md5sum.txt $RECYCLE.BIN System Volume Information
EFI pics Remove_LiLi.bat
install pool

i can't dismount the partition and remount to write /EFI/ubuntu on this partition.
ubuntu@ubuntu:~$ sudo umount /cdrom
umount: /cdrom: target is busy
        (In some cases useful info about processes that
         use the device is found by lsof(8) or fuser(1).)
ubuntu@ubuntu:~$ sudo lsof +D /cdrom
lsof: WARNING: can't stat() fuse.gvfsd-fuse file system /run/user/999/gvfs
      Output information may be incomplete.
ubuntu@ubuntu:~$ sudo fuse /cdrom
sudo: fuse: command not found
ubuntu@ubuntu:~$ sudo fuser /cdrom
ubuntu@ubuntu:~$ sudo fuser -v /cdrom
                     USER PID ACCESS COMMAND
/cdrom: root kernel mount /cdrom
ubuntu@ubuntu:~$ sudo umount -lv /cdrom
umount: /cdrom (/dev/sda1) unmounted
ubuntu@ubuntu:~$ sudo ls /cdrom
ubuntu@ubuntu:~$ sudo mkdir /mnt/A
ubuntu@ubuntu:~$ sudo mount -v /dev/sda1 /mnt/A
mount: /dev/sda1 is already mounted or /mnt/A busy
ubuntu@ubuntu:~$