adb remount failed

shanshanx@shanshanx:~$ adb root
adbd is already running as root
shanshanx@shanshanx:~$ adb remount
dm_verity is enabled on the system partition.
Use "adb disable-verity" to disable verity.
If you do not, remount may succeed, however, you will still not be able to write to these volumes.
remount of system failed: Read-only file system
remount failed

you can use
1.adb disable-verity and than adb reboot ( may be not work sometimes)

2.device/xx/baytrail/xx/fstab
/dev/block/by-name/android_system       /system         ext4    ro                                         wait,verify  
u can got it ,we can remove verify and than rebuild(u must has codebase)