有时候,umount一个分区,提示设备忙,加上 -f 参数也不管用,然后 lsof 路径 又找不到任何进程,这时候就可以用 sudo umount -l 路径 卸载之。
man 如是说:

-f Force unmount (in case of an unreachable NFS system). (Requires kernel 2.1.116 or later.)

-l Lazy unmount. Detach the filesystem from the filesystem hierarchy now, and cleanup all references to the filesystem as soon as it is not busy anymore. (Requires kernel 2.4.11 or later.)