nr_free_zone_pages(9)

💖 nr_free_zone_pages(9) 💖

okay so you found the kernel API manual, bestie — welcome to nr_free_zone_pages, straight out of the Kernel API Manual. she counts pages that live beyond the high watermark, and honestly? iconic behavior. let's get into it 🫶

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✨ SYNOPSIS ✨

unsigned long nr_free_zone_pages (int offset );

that's it. one arg. one unsigned long coming back at you. we love a simple signature, no cap 💅

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🌸 ARGUMENTS 🌸

• offset — the zone index of the highest zone. like, the top of the range she's gonna walk, iykyk 🦋

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🎀 DESCRIPTION 🎀

so here's the vibe: nr_free_zone_pages counts the number of pages that are beyond the high watermark within all zones at or below a given zone index. every zone at or under offset, she's checking it. thorough queen 👑

for each zone, the number of pages is calculated as:

nr_free_zone_pages = managed_pages - high_pages

literally that's the whole formula. managed_pages minus high_pages, per zone. math ate and left no crumbs ✨

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⭐ RETURN ⭐

number of pages beyond high watermark. that's the whole return value, fr fr 💜

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🌈 SEE ALSO 🌈

bestie there are so many friends in this friend group, buckle up:

• Kernel file ./mm/page_alloc.c — that's where the family lives 🏠
• __get_pfnblock_flags_mask(9)
• get_pfnblock_bit(9)
• get_pfnblock_migratetype(9)
• __set_pfnblock_flags_mask(9)
• set_pfnblock_bit(9)
• clear_pfnblock_bit(9)
• set_pageblock_migratetype(9)
• __move_freepages_block_isolate(9)
• __putback_isolated_page(9)
• __free_pages(9)
• free_pages(9)
• alloc_pages_exact(9)
• alloc_pages_exact_nid(9)
• free_pages_exact(9)
• nr_free_buffer_pages(9)
• find_next_best_node(9)
• free_reserved_pages(9)
• setup_per_zone_wmarks(9)
• __free_contig_range(9)
• alloc_contig_frozen_range(9)
• alloc_contig_range(9)
• alloc_contig_frozen_pages(9)
• alloc_contig_pages(9)
• free_contig_frozen_range(9)
• free_contig_range(9)
• alloc_pages_nolock(9)

like I said. big friend group. go say hi 💖

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ngl this page is short and sweet — no gotchas, no deprecation drama, no scary undefined behavior. just a page counter doing her thing. slay 🧚

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and that's the whole page, bestie!! this one came from the ./mm corner of the tree, dated October 2026, and the header up top says nr_free_zone_pages(9) in the Kernel API Manual — so you know exactly where to find her again 💅✨ see you in the next manpage, mwah 🍓