How does the Linux kernel manage and free occupied RAM?

The Linux kernel manages RAM through the Memory Management Unit (MMU). The main mechanisms include:

1. Memory allocation: the kernel allocates memory to processes via system calls (e.g., malloc in user space), using fixed-size pages.

2. Caching and buffering: the kernel uses free memory for caching files and buffers to speed up data access.

3. Swapping: when RAM is insufficient, the kernel moves inactive pages to swap space (a file or partition on disk), freeing RAM for active processes.

4. Memory freeing: when memory is needed, the kernel clears caches and buffers, and unloads unused pages.

5. Garbage collection: in the context of memory, the kernel does not perform garbage collection, but frees pages that are no longer needed.

Thus, Linux efficiently manages memory, balancing performance and resource availability.