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

CONFIG_ARCH_TASK_STRUCT_ALLOCATOR (not configurable)

configname: CONFIG_ARCH_TASK_STRUCT_ALLOCATOR

Linux Kernel Configuration
└─>General architecture-dependent options
└─>ARCH_TASK_STRUCT_ALLOCATOR
In linux kernel since version 3.1 (release Date: 2011-10-24)