default or selected kernelversion does not have config value CONFIG_FRONTSWAP.
Result is shown for kernelversion 6.9.9

CONFIG_FRONTSWAP (not configurable)

modulename: frontswap.ko

configname: CONFIG_FRONTSWAP

Linux Kernel Configuration
└─>Memory Management options
└─>FRONTSWAP
In linux kernel since version 3.1 (release Date: 2011-10-24)  
source code:
mm/frontswap.c
is depended by
CONFIG_ZSWAP