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Use /proc/self/pagemap to Inspect Your Process Layout

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Understand OOM Killer: Read Linux oom_kill.c Source Implement Swapping: Write Pages to Swap File

Language

Compiler

2.0s Limit 256MB

Implementation

Read and parse /proc/self/pagemap.

Requirements:

Open /proc/self/pagemap
Read page table entries for virtual addresses
Parse PFN (physical frame number) and flags
Check present, dirty, file-backed, anonymous flags
Print entry information
Cross-reference with /proc/self/maps
Allocate memory and check its PTEs

Success Criteria:

Successfully open and read pagemap
Parse binary format correctly
Display PFN and flags
Identify present vs swapped pages

Why This Matters

Tools like smem, pmap, and Chrome's about://memory-internals all read /proc/PID/pagemap to report real per-process memory usage instead of guessing from virtual address space size. Getting a bit offset wrong — present is bit 62, not 61 — silently reports swapped-out pages as resident, exactly the kind of bug that makes memory-usage dashboards lie to operators.

Hints

0 / 3 revealed

Validation Suite

main.c

Workspace 1.0