folio_putback_lru(9)

✨ folio_putback_lru(9) ✨

okay bestie, welcome to the Kernel API Manual 🎀 — this is the folio_putback_lru page and it's literally the "oops put it back" of the memory-management world. no cap.

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💖 NAME 💖

folio_putback_lru — put a previously isolated folio back onto the appropriate LRU list. it's giving "return to sender, but make it kernel" 🦋

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🌸 SYNOPSIS 🌸

void folio_putback_lru (struct folio *folio );

that's it. that's the whole signature. no return value, no drama, no hidden parameters. slay 💅

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⭐ ARGUMENTS ⭐

• folio — the folio that's getting returned to an LRU list. that's your main character right there 👑

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🌈 DESCRIPTION 🌈

so here's the vibe: you take a folio that was previously isolated and you add it to the appropriate LRU list. that's the whole job. iconic, low-effort, high-impact 🫶

and like — big caveat incoming — the folio may still be unevictable for other reasons. so don't go thinking this magically makes it reclaimable, bestie, because it does not 💀 it just goes back on the list. folio_putback_lru does not read the room on your behalf.

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🧚 CONTEXT 🧚

listen closely, this part is non-negotiable:

• lru_lock must not be held 🔒🚫
• interrupts must be enabled ⚡✅

get either of those wrong and, like, don't. just don't 🙈

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🦋 SEE ALSO 🦋

• Kernel file ./mm/vmscan.c
• writeback_throttling_sane(9)
• lruvec_lru_size(9)
• remove_mapping(9)
• folio_isolate_lru(9)
• check_move_unevictable_folios(9)

go read folio_isolate_lru(9) next, it's the prequel 😭🔥

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fr fr: this page lives in ./mm, it's the October 2026 edition, and it's folio_putback_lru(9) all the way down. now go put that folio back where it belongs 💜🎀