Judge a process is critical one or not at Kernal driver

Hello! Everyone!

I have been searching information on process info. I would like to know whether 

a process is critical one or not. I have already done it within the application layer.

However, I cannot judge whether a process is critical at the Driver layer(kernal)

I am a security software developer. I need to know whether a process is critical

so that I do not kill a critical process to avoid windows crash.

Can you help me on this issue?

Lots of love,