unpin_folio(9)

💖 unpin_folio — kernel API manual, bestie edition 💖

okay so this is unpin_folio(9) from the Kernel API Manual, and it is genuinely one of the shortest little pages ever, so let's get into it 🫶

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✨ NAME ✨

unpin_folio — release a dma-pinned folio. that's it. that's the whole job. unpin_folio releases a folio that got dma-pinned. iconic, minimal, does exactly what it says 💅

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🌸 SYNOPSIS 🌸

void unpin_folio (struct folio *folio );

no return value, no drama, just void and vibes ✨

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🎀 ARGUMENTS 🎀

• folio — pointer to the folio that's getting released. yep, that's the whole argument list. one (1) folio, handed over so it can be set free 🦋

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💜 DESCRIPTION 💜

so here's the lore: folios that were pinned via memfd_pin_folios or other similar routines must be released — and you've got two ways to do it, either with unpin_folio or with unpin_folios. that's the rule, no cap. pinned means somebody's gotta unpin it eventually, and this is one of your two doors out 🚪✨

lowkey important: the original says must be released, so like… don't just leave your pinned folios hanging, bestie 😭

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🌈 SEE ALSO 🌈

it's giving "let me introduce you to the whole friend group" — the Kernel file ./mm/gup.c crew, all of them, in order:

• try_grab_folio(9)
• unpin_user_page(9)
• folio_add_pin(9)
• unpin_user_pages_dirty_lock(9)
• unpin_user_page_range_dirty_lock(9)
• unpin_user_pages(9)
• unpin_user_folio(9)
• unpin_folios(9)
• try_grab_folio_fast(9)
• follow_page_mask(9)
• __get_user_pages(9)
• fixup_user_fault(9)
• populate_vma_page_range(9)
• fault_in_writeable(9)
• fault_in_subpage_writeable(9)
• fault_in_readable(9)
• get_dump_page(9)
• get_user_pages_remote(9)
• get_user_pages(9)
• get_user_pages_fast_only(9)
• get_user_pages_fast(9)
• pin_user_pages_fast(9)
• pin_user_pages_remote(9)
• pin_user_pages(9)
• memfd_pin_folios(9)
• folio_add_pins(9)

like, the entire ./mm friend group showed up to the group chat 🔥 go read them all, iykyk 👑

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and that's the page, babe — brought to you from ./mm, dated October 2026, and filed under unpin_folio(9) in the Kernel API Manual. mwah 💋✨