Practice Exam 2, Problem 4: The Free List

Midterm 1 practice exam 2, problem 4 of 5 · Length: 10:36 · Exercises: 32k_physical_memory (Week 7) · Answer key: Solutions (PDF)

Worked on pages 15 to 18, with the allocator's code beside each part: (a) pgroundup of end, the pages init frees, the list it leaves, and six kalloc and kfree calls traced; (b) kfree with its last two lines swapped: a page that points at itself, two lost pages, and the self-test check that fails; (c) count_free, what it returns, and why the list lives in the free pages themselves. The answer key's handwriting is written onto the exam page as each step is worked.

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