adb remount 失败remount failed: Operation not permitted

1. 进入shell

adb shell

2. shell下输入命令

shell@android:/ $ su
shell@android:/ # mount -o rw,remount -t yaffs2 /dev/block/mtdblock3 /system
shell@android:/ # chmod 777 /system 
shell@android:/ # cd system
shell@android:/system # chmod 777 app
shell@android:/system # cd app
shell@android:/system/app # exit
shell@android:/ $ exit