Linux Internals: How /proc/self/mem writes to unwritable memory
Summary
This deep-dive explains how /proc/self/mem can write to unwritable memory, revealing punch-through semantics and the hardware/VM tricks behind it. It analyzes how the kernel bypasses MMU constraints via get_user_pages, kmap, and copy_to_user_page, and discusses implications for kernel vs user-space memory permissions and security.