default or selected kernelversion does not have config value CONFIG_BLK_CGROUP.
Result is shown for kernelversion 5.4.194

CONFIG_BLK_CGROUP (not configurable)

modulename: blk-cgroup.ko

configname: CONFIG_BLK_CGROUP

Linux Kernel Configuration
└─>Enable the block layer
└─>BLK_CGROUP
In linux kernel since version 2.6.33 (release Date: 2010-02-24)  
Generic block IO controller cgroup interface. This is the common
cgroup interface which should be used by various IO controlling
policies.

Currently, CFQ IO scheduler uses it to recognize task groups and
control disk bandwidth allocation (proportional time slice allocation)
to such task groups.

source code:
depends
CONFIG_BLOCK
CONFIG_CGROUPS or CONFIG_CFQ_GROUP_IOSCHED
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is selected by
CONFIG_BLK_CGROUP_IOCOST
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