s390_wiggle_split_folio(9)

💅 s390_wiggle_split_folio(9) — the Kernel API Manual, but make it make sense ✨

okay so bestie, listen. this is s390_wiggle_split_folio from the s390 kernel crew, and honestly? the name alone is giving main character energy. her whole job is wiggling — like, she tries to drain away the extra references hanging onto a folio, and then if that folio is large, she goes ahead and splits it. no cap, that's the entire plot 🎀

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🌸 NAME 🌸

s390_wiggle_split_folio — try to drain extra references to a folio and split the folio if it is large.

like literally that's it. that's her. she wiggles, she drains, she splits. periodt 💅

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✨ SYNOPSIS ✨

int s390_wiggle_split_folio (struct mm_struct *mm , struct folio *folio );

look at that signature. iconic. she takes two things and she gives you back an int. slay 💖

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🦋 ARGUMENTS 🦋

• mm — the mm containing the folio to work on. yep, that mm. the one with the folio in it 👑
• folio — the folio. it's the folio. the star of the show 🍓

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💀 CONTEXT 💀

okay this part is important so pay attention bestie 🙈

• You must be holding an extra reference to the folio when you call her. not optional. required. non-negotiable.
• The mm lock should not be held. so like, put it down first, mkay?

fr fr, get the context wrong and you're gonna have a bad time 😭

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🌈 RETURN 🌈

• 0 — the operation was successful 💖 everything worked, she ate, no crumbs.
• -EAGAIN — splitting the large folio was not successful, BUT another attempt can be made. so like, not a flop, just a "try again" moment 🫶
• -EINVAL — in case of other folio splitting errors. yeah, those ones. the other ones 💀

also go check split_folio if you want the whole story, iykyk 👀

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⭐ SEE ALSO ⭐

• Kernel file ./arch/s390/kernel/uv.c
• __make_folio_secure(9)
• uv_find_secret(9)
• uv_retrieve_secret(9)

go read them. all of them. i'll wait 🧚

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and that's the whole page bestie!! 💜 this little gem lives in ./arch/s390/kernel and the version/date stamp on it says October 2026 — so yeah, she's from the future, and she's still wiggling folios. obsessed. stay hydrated, hold your extra refs, and never grab the mm lock. mwah 🫶✨🌸