__memcg1_swapout(9)

💅 __memcg1_swapout(9)

okay so this is a page from the Kernel API Manual, and bestie, we're talking about __memcg1_swapout — the little function that transfers a memsw charge to swap. yes i know, very serious kernel business, but stay with me, it's actually iconic.

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✨ SYNOPSIS ✨

void __memcg1_swapout (struct folio *folio , struct swap_cluster_info
*ci );

that's the whole signature, no cap. two args, both pointers, and it returns void — so like, nothing comes back, it just does the thing. 💅

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🎀 ARGUMENTS 🎀

• folio — the folio whose memsw charge we're transferring. this is the main character of the whole operation, fr fr. 🦋
• ci — the locked swap cluster holding the swap entries. it's already locked, so don't you dare touch the lock, bestie. 🔒

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🌸 DESCRIPTION 🌸

so what does it actually do? it transfers the memsw charge of folio over to the swap entry stored in folio->swap. that's it, that's the vibe. the charge packs its bags and moves to the swap entry. slay. ✨

ngl it's a short description because the function is a short function — sometimes less is more, and this is giving "confident, precise, knows exactly what it's doing" energy. 👑

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💀 CONTEXT 💀

okay this part is highkey important so read it twice:

• folio must be isolated, unmapped, locked, and is just about to be freed.
• the caller must disable IRQs.
• the caller must hold the swap cluster lock.

🫶 requirements check before you call this, bestie — it's not optional. the folio is literally about to be freed, so the state has to be exactly right or things get extremely not-cute. 🙈

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🦋 SEE ALSO 🦋

go read these next, they're all in the kernel file ./mm/memcontrol-v1.c and they're all part of the same little friend group:

• memcg1_swapin(9)
• mem_cgroup_oom_synchronize(9)
• vmpressure_prio(9)
• vmpressure_register_event(9)
• vmpressure_unregister_event(9)

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and that's the page! 💖 this one lives in ./mm and the version/date on it is October 2026, which honestly feels like a future vibe but here we are. stay charged (memsw-ly speaking), lock your clusters, and i'll see you in the next manpage. mwah! 💅🎀