folio_check_splittable(9)

💅 folio_check_splittable(9) — the Kernel API Manual, but make it cute

okay bestie, gather round, because today we're looking at folio_check_splittable, straight out of the Kernel API Manual (section 9, kernel girlies rise). it's giving "small function, big responsibility" and honestly? we love her for it. 🎀

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✨ NAME ✨

folio_check_splittable — literally just checks if a folio can be split down to a given order. that's it. that's the whole vibe check. 🦋

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🌸 SYNOPSIS 🌸

int folio_check_splittable (struct folio *folio , unsigned int new_order
, enum split_type split_type );

look at her. three params, one int, zero drama. ✨

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💖 ARGUMENTS 💖

• folio — the folio we're trying to split, bestie. this is our main character. 👑
• new_order — the smallest order of the after-split folios. and like, lowkey important context here: buddy allocator–style splitting generates folios with orders all the way from the folio's order - 1 down to new_order, so this isn't just "one number," it's the floor of a whole lil cascade. 🌈
• split_type — uniform or non-uniform split. pick your fighter. 💅

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🫶 DESCRIPTION 🫶

so folio_check_splittable checks whether folio can actually be split to new_order using the split_type method. that's the tea. 🍓

⚠️ and bestie, do NOT skip this: the truncated folio check must come first. like, before you do anything else. it's a prerequisite, not a suggestion. 🙈

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🔥 CONTEXT 🔥

folio must be locked. no cap. lock your folio before you come to this function, or you're gonna have a bad time. 💀

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⭐ RETURN ⭐

• 0 — slay, the folio can be split to new_order ✅
• otherwise — an error number gets returned 😭 (no zero, no party)

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🧚 SEE ALSO 🧚

all the kernel file besties from ./mm/huge_memory.c, linking arms in a little conga line:

• vmf_insert_pfn_pmd(9)
• vmf_insert_pfn_pud(9)
• vmf_insert_folio_pud(9)
• touch_pmd(9)
• zap_huge_pmd(9)
• __split_unmapped_folio(9)
• __folio_split(9)
• folio_split_unmapped(9)
• folio_split(9)
• min_order_for_split(9)

iykyk. go read them. obsessed with all of them fr fr. 💜

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kisses and good vibes from ./mm 🫶 — this iconic little page is dated October 2026, and it lives in folio_check_splittable(9) forever. periodt. 💖