Linux umount操作报device is busy怎么办？

[root@qs-wg-db1 ~]# df -lh
Filesystem            Size  Used Avail Use% Mounted on
/dev/sdb3             125G  3.3G  115G   3% /
/dev/sdb1              99M   12M   82M  13% /boot
tmpfs                 3.9G     0  3.9G   0% /dev/shm
/dev/sda1             275G   72G  189G  28% /u01
/dev/sdc1              10G  2.0G  8.1G  20% /datatmp

[root@qs-wg-db1 ~]# fuser -km /datatmp
[root@qs-wg-db1 ~]# df -lh
Filesystem            Size  Used Avail Use% Mounted on
/dev/sdb3             125G  3.3G  115G   3% /
/dev/sdb1              99M   12M   82M  13% /boot
tmpfs                 3.9G     0  3.9G   0% /dev/shm
/dev/sda1             275G   72G  189G  28% /u01
/dev/sdc1              10G  2.0G  8.1G  20% /datatmp
[root@qs-wg-db1 ~]# umount /datatmp
[root@qs-wg-db1 ~]# df -lh
Filesystem            Size  Used Avail Use% Mounted on
/dev/sdb3             125G  3.3G  115G   3% /
/dev/sdb1              99M   12M   82M  13% /boot
tmpfs                 3.9G     0  3.9G   0% /dev/shm
/dev/sda1             275G   72G  189G  28% /u01
 

[root@qs-wg-db1 ~]#fuser –km /dev/cdrom
[root@qs-wg-db1 ~]#eject  -- 弹出光驱
 

# mkdir cdrom
# mount /dev/cdrom /mnt/cdrom
或者
# mount /dev/cdrom /media/cdrom
 

[root@qs-wg-db1 ~]# man fuser
FUSER(1)       User Commands     FUSER(1)
 
NAME
       fuser - identify processes using files or sockets
 
SYNOPSIS
       fuser [-a|-s|-c] [-4|-6] [-n  space ] [-k [-i] [-signal ] ] [-muvf] name
       fuser -l
       fuser -V
 
DESCRIPTION
       fuser displays the PIDs of processes using the specified files or file systems.  In the default display mode, each file name is followed by a letter denoting the  type
       of access:
              c      current directory.
              e      executable being run.
              f      open file. f is omitted in default display mode.
              F      open file for writing. F is omitted in default display mode.
              r      root directory.
              m      mmap'ed file or shared library.
 
       fuser  returns a non-zero return code if none of the specified files is accessed or in case of a fatal error. If at least one access  has  been  found,  fuser  returns zero.
       In  order  to  look  up processes using TCP and UDP sockets, the corresponding name space has to be selected with the -n option. By default fuser  will  look  in  both IPv6  and IPv4 sockets. To change the default, behavior, use the -4 and -6 options. The socket(s) can be specified by  the  local  and  remote  port,  and  the  remote address.  All  fields  are  optional, but commas in front of missing fields must be present:
       [lcl_port][,[rmt_host][,[rmt_port]]]
       Either symbolic or numeric values can be used for IP addresses and port numbers.
     
fuser outputs only the PIDs to stdout, everything else is sent to stderr.
 
OPTIONS
       -a     Show all files specified on the command line. By default,  only  files  that are accessed by at least one process are shown.
       -c     Same as -m option, used for POSIX compatibility.
       -f     Silently ignored, used for POSIX compatibility.
       -k     Kill  processes  accessing the file. Unless changed with -signal, SIGKILL is sent. An fuser process never kills itself, but may  kill  other  fuser  processes.  The  effective user ID of the process executing fuser is set to its real user ID before attempting to kill.
       -i     Ask the user for confirmation before  killing  a  process.  This  option  is silently ignored if -k is not present too.
       -l     List all known signal names.
       -m    name  specifies  a  file  on a mounted file system or a block device that is mounted. All processes accessing files on that file system are listed.  If adirectory  file  is  specified, it is automatically changed to name/. to use any file system that might be mounted on that directory.
 
       -n space Select a different name  space.  The  name  spaces  file  (file  names,  the default),  udp  (local  UDP ports), and tcp (local TCP ports) are supported. For ports, either the port number or the symbolic name can be specified.  If  there  is no ambiguity, the shortcut notation name/Ispace (e.g. 80/tcp ) can be used.
       -s     Silent operation. -u and -v are ignored in this mode.  -a must not  be  used with -s.
       -signal Use  the specified signal instead of SIGKILL when killing processes. Signals can be specified either by name (e.g. -HUP) or by  number  (e.g.  -1).  This option is silently ignored if the -k option is not used.
       -u     Append the user name of the process owner to each PID.
       -v     Verbose  mode.  Processes are shown in a ps-like style. The fields PID, USER and COMMAND are similar to ps. ACCESS shows how  the  process  accesses  the file.  If  the access is by the kernel (e.g. in the case of a mount point, awap file, etc.), kernel is shown instead of the PID.
       -V     Display version information.
       -4     Search only for IPv4 sockets. This option must  not  be  used  with  the  -6 option and only has an effect with the tcp and udp namespaces.
       -6     Search  only  for  IPv6  sockets.  This  option must not be used with the -4 option and only has an effect with the tcp and udp namespaces.
       -      Reset all options and set the signal back to SIGKILL.
FILES
/proc     location of the proc file system