6efb5ece_t2_____Unix__Linux_System_Call__Error_Code
[Description] source is already mounted. Or, it cannot be remounted read-only, because it still holds files open for writing. Or, it cannot be mounted on target because target is still busy (it is the working directory of some task, the mount point of another device, has open files, etc.). Or, it could not be unmounted because it is busy. [Error Code] 
EBUSY
umount2() - Unix, Linux System Call