貌似因為 U盤是 fat32的。所以你在分區的選項之前先輸入 o ，在輸入w ，接下來再按視屏上的操作就可以了。以下是我網上看到的解決方法：

How To Fix "Warning: Re-reading the partition table failed with error 22: Invalid argument" Error on Linux
If you are getting the following error while trying to change the default fat32 partition on a new drive to another linux partition type, I might have the answer for you.
This is the error that you keep getting:
WARNING: Re-reading the partition table failed with error 22: Invalid argument.
The kernel still uses the old table.
The new table will be used at the next reboot.
Syncing disks.
Here's the way to fix it, noting that this will wipe your drive. Start up fdisk for the appropriate drive (may not be /dev/sde for you)
fdisk /dev/sde
Then use the "o" option, which according to the menu is:
? ?o? ?create a new empty DOS partition table
Now write the changes to disk with "w", and then open up fdisk again. Now you can create your partition.
Don't forget to actually create the filesystem for your new partition, which can be done with "mkfs". You can also use the shortcut method like this:
mkfs.reiserfs /dev/sde1
The nice thing is that the shortcut is easy to type with command line completion.