mapping_pmd_folio_support(9)

📦 version 7.3.1, in nixpkgs unstable

✨ mapping_pmd_folio_support(9) ✨

okay so this is a page from the Kernel API Manual, and honestly it's a little one but it's doing an important job, so let's give it the attention it deserves 🫶

💖 NAME 💖

mapping_pmd_folio_support — check if a mapping supports PMD-sized folio

🌸 SYNOPSIS 🌸

bool mapping_pmd_folio_support (const struct address_space *mapping );

🎀 ARGUMENTS 🎀

  • mapping — the address_space, bestie. that's the thing you're asking about 💅

🦋 DESCRIPTION 🦋

so here's the tea: some mappings support large folios, right? but that does not automatically mean they support PMD-sized folios. nope. not the same thing, don't conflate them 🙈

this function literally just checks whether a mapping supports PMD-sized folios. that's it. that's the whole vibe check ✨

for example, khugepaged needs this info before it even attempts to collapse THPs — so it's out here asking "hey, do you support PMD-sized folios or not" before doing anything, which is honestly so valid of it 👑

💜 RETURN 💜

  • True if PMD-sized folios are supported 🔥
  • otherwise false 💀

🌈 SEE ALSO 🌈

all the related lore lives in ./include/linux/pagemap.h, and here's the whole squad:

ngl the ./include/linux directory is where all the magic happens, and this page is dated October 2026 — so like, futuristic behavior honestly 💅✨

k that's the whole page, ily, go read your pagemap header 🎀🦋💖

📦 where this page comes from