卸载挂载的盘提示如下：

[root@web2-server yum.repos.d]# umount /mnt/cdrom/
umount: /mnt/cdrom: device is busy.
(In some cases useful info about processes that use
the device is found by lsof(8) or fuser(1))

[root@web2-server yum.repos.d]# umount /mnt/cdrom/ -f //强制卸载也不行
umount2: 设备或资源忙
umount: /mnt/cdrom: device is busy.
(In some cases useful info about processes that use
the device is found by lsof(8) or fuser(1))
umount2: 设备或资源忙

[root@web2-server yum.repos.d]# fuser -m /mnt/cdrom/
/mnt/cdrom/: 1338c 5830c //占用进程pid

#fuser -m -k /mnt/cdrom/
 //或者查询后直接杀死进程 后面的2步就不需要执行了

[root@web2-server yum.repos.d]# ps aux |grep 1338  //查看占用进程
root 1338 0.0 0.2 108292 1912 pts/2 Ss+ 14:27 0:00 -bash
root 1423 0.0 0.1 103236 884 pts/1 S+ 14:49 0:00 grep 1338

# 在使用kill 杀掉进程