Teach you to change the kernel source code--sysfs virtual file system 2

Environment:uos
Kernel code version:4.19.90

First, in the previous article, custom folders and files were created in /sys/.
So, ask a question:
Why is it under the /sys/ folder by default when using the kobject_create_and_add() kernel interface to create a node?

Go to start_kernel with questions to find answers.

This is the calling process I found myself.

The last function sysfs_create_dir_ns() creates a folder, which has been changed by me.
That part of the change is the answer.
Look at the code first:

/** * When the interface is found to be NULL, why is it in the /sys directory by default */if (kobj->parent){parent = kobj-&