folio_use_access_time(9)

💅 folio_use_access_time — from the Kernel API Manual, section 9, bestie

okay so this one is a lil kernel function from the 9 section of the manual (that's the kernel API one, iykyk) and honestly? it's giving "just a quick check, no big deal" ✨

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🌸 NAME 🌸

folio_use_access_time — check if a folio reuses cpupid for page access time 🫶

like literally, it's a yes-or-no vibe check on one single folio.

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🎀 SYNOPSIS 🎀

bool folio_use_access_time (struct folio *folio );

one argument, one boolean answer, that's the whole main character moment 💅

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🦋 ARGUMENTS 🦋

• folio — the folio to check. that's it. that's the argument. the folio. the one getting checked. 👑

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✨ DESCRIPTION ✨

okay so here's the tea ☕ — a folio's _last_cpupid field gets repurposed by memory tiering. like, it's got a whole second job now, no cap.

and in memory tiering mode specifically, the cpupid of a slow memory folio — and bestie, note that it's not toptier memory, we're talking slow memory only — is used to record page access time. 🕐

so if you're wondering "hmm is this folio's _last_cpupid doing access-time duty or not", that's exactly what this function is here to tell you. slay.

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🔥 RETURN 🔥

the folio's _last_cpupid is used to record page access time ✅ (so like, the return value tells you whether that's the case — fr fr)

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🌈 SEE ALSO 🌈

• Kernel file ./mm/memory-tiers.c
• next_demotion_node(9)
• register_mt_adistance_algorithm(9)
• unregister_mt_adistance_algorithm(9)
• mt_calc_adistance(9)

go read those too, they're literally the rest of the memory tiering friend group 🫶💜

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and that's the whole page, bestie 🎀 — this one comes courtesy of ./mm, dated October 2026, and it's folio_use_access_time(9) all day. periodt. 💅✨