Hi,
The accepted answer is - Where shared resources are accessed
But, I think a shared resource does not need to be always a critical section.
There could be read-only shared resources but not the critical section.
"The sequence of instructions between acquire and release is often called a critical section, and the lock protects list."
Above is the statement from the chapter 4 - Locking XV6 Book
Thanks & Regards,
Pritesh