kernel: return from interrupt

Hi,

I was under the impression that the 5.3 release had an option for full
preemption.
If I am correct, why does the kernel refuse to schedule on a
return_from_interrupt if its not
going back to userland? 
I can understand this being a problem if interrupts were nested, or
return from a page fault in a
critical section. 
Please correct me if I am wrong, but if a *high* priority interrupt
thread is ready to run, it
should be given a chance. Presuming the *interrupted* kernel path is
going to give up the CPU
fast enough is probably not a good idea. 

I hope I have sent this to the right mailing list.

Thanks,
Anurekh