folio_add_pin(9)

💖 folio_add_pin(9) — the Kernel API Manual, bestie edition 🎀

okay so real talk, this one's from the Kernel API Manual and it's short but it's important, so pay attention for like two seconds 🫶

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✨ NAME ✨

folio_add_pin — literally just "try to get an additional pin on a pinned folio". that's it. that's the whole vibe 💅

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🌸 SYNOPSIS 🌸

void folio_add_pin (struct folio *folio );

yes girl, void return, so nothing comes back out — it just does the thing ✨

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🦋 ARGUMENTS 🦋

• folio — the folio that's getting pinned. the main character of this whole operation 👑

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💜 DESCRIPTION 💜

so here's the tea: you hit up folio_add_pin when you want an additional pin on a folio that you already have a pin on. no cap — it's the "one more won't hurt" of the folio world 🍓

and the little exception that eats: if the folio is a zero_page, this function makes no change at all. absolutely nothing. it's giving "saw it, didn't care" 💀

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🌈 SEE ALSO 🌈

bestie this list is long, so buckle up. it's all the siblings and adjacent besties over in the Kernel file ./mm/gup.c:

• try_grab_folio(9)
• unpin_user_page(9)
• unpin_folio(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, go read all of them, i'll wait 💅 ngl that's the whole friend group right there 🔥

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💡 tiny vibe check: this page lives under ./mm, dated October 2026 — so when you're citing it in your notes, that's the source and the date, periodt 👑

hope that slayed for you, mwah 😭💖 🌸🦋✨