folio_precise_page_mapcount(9)

💅 folio_precise_page_mapcount(9) — from the Kernel API Manual, bestie ✨

okay so real talk, this one's from the kernel API manual and it's literally the vibe check for how many times a page got mapped 🫶

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✨ NAME ✨

folio_precise_page_mapcount — the exact number of mappings of this folio page, no cap 💖

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🎀 SYNOPSIS 🎀

int folio_precise_page_mapcount (struct folio *folio , struct page *page
);

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🌸 ARGUMENTS 🌸

• folio — the folio, bestie. that's the whole thing.
• page — the page. yes queen, that one.

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🦋 DESCRIPTION 🦋

so it returns the number of present user page table entries that reference this page, as tracked via the RMAP — either referenced directly (PTE) or as part of a larger area that covers this page (e.g., PMD). it's giving precise. it's giving tracked. iykyk 💅

use this function only for the calculation of existing statistics (USS, PSS, mapcount_max) and for debugging purposes (/proc/kpagecount).

and the big one, the line that matters most:

do not add new users. periodt. 🚫

like, this is not a "new feature" girlie, this is a "look at the existing numbers" girlie. do not come in here inventing a brand new caller, i'm begging 😭

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👑 RETURN 👑

the number of mappings of this folio page, purr 💜

and 0 for folios that are not mapped to user space or are not tracked via the RMAP (the example the manpage gives is the shared zeropage, iconic behaviour honestly).

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🌈 SEE ALSO 🌈

• Kernel file ./fs/proc/internal.h
• folio_average_page_mapcount(9)

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✨ and that's the page!! source/version: ./fs/proc, dated October 2026 — stay mapped, stay tracked, and remember: statistics only, no new users, mwah 🎀💖🦋