CONFIG_PREEMPTION is selected by CONFIG_PREEMPT and by CONFIG_PREEMPT_RT. Both PREEMPT and PREEMPT_RT require the same functionality which today depends on CONFIG_PREEMPT.
The following series adjusts the core and x86 code to use CONFIG_PREEMPTION where appropriate and extends the x86 dumpstack implementation to display PREEMPT_RT instead of PREEMPT on a RT enabled kernel. Thanks, tglx