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How the OS locates evicted pages during a page fault

This easy operating systems question tests your understanding of how modern kernels handle page faults—one of the most fundamental operations in virtual memory management. It asks where and how the OS discovers a page that has been swapped to disk when a process requests it.

To answer, you need to reason about the bookkeeping structures the OS maintains to track which virtual pages have been evicted and where on disk they currently reside. The question probes whether you understand the relationship between page-table entries, metadata, and secondary storage, and how the kernel uses that information to retrieve missing pages. This is foundational material covered in depth in Operating Systems: Three Easy Pieces.

• The role of the present bit in page-table entries
• Metadata storage for swapped pages
• The page fault handler's lookup and retrieval process
• Disk I/O initiation and blocking in the kernel