Using System Calls from kernel space

["endeavor john" <jendeavor@xxxxxxxxx>]

Hi All ,
            
I wanted to use a system call from kernel module to change the priority
of the process using sys_sched_setscheduler from kernel space 
after using get_fs by modifying the addr_limit of the task to KERNEL_DS using set_fs and get_fs  apis.
 
I wanted to what will be the disadvantage in using the System Calls from kernel space if  it not any file system call.
Thanks and Regards,
John Endeavour