free_iova_fast(9)

💖 free_iova_fast(9) 💖

okay so bestie, welcome to the Kernel API Manual ✨ — yes we're literally in the kernel docs together, hold my iced coffee 🧋. Today's main character is free_iova_fast, a little function living its best life in the IOMMU world 🦋.

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🌸 NAME 🌸

free_iova_fast — frees an iova pfn range and yeets it back into the rcache 🎀

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✨ SYNOPSIS ✨

void free_iova_fast (struct iova_domain *iovad , unsigned long pfn ,
       unsigned long size );

like, that's the whole signature. no cap. 💅

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🎀 ARGUMENTS 🎀

• iovad — the iova domain in question 👑 — it's giving "which sandbox are we playing in".
• pfn — a pfn that was allocated previously 🫶 — yes bestie it has to be one you already grabbed, not a random one you found on the floor.
• size — the # of pages in the range 📏.

so about that last one — the original page just casually drops the whole function description right under size (iconic placement, honestly 💀), and it says: this function frees an iova range by trying to put it into the rcache first, and if that fails it falls back to regular iova deallocation via free_iova 🔥. so like — rcache first, free_iova as the backup plan. not me having a whole fallback strategy 😭💜.

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🦋 SEE ALSO 🦋

kernel file ./drivers/iommu/iova.c 👀 and the whole squad:

• alloc_iova(9)
• find_iova(9)
• __free_iova(9)
• free_iova(9)
• alloc_iova_fast(9)
• put_iova_domain(9)
• reserve_iova(9)

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lowkey a reminder that this is kernel territory — read the args carefully before you call it, mkay? 🌈

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anyway that's the whole vibe check 🧚 — brought to you by ./drivers/iommu, dated October 2026, and yes the page title was free_iova_fast(9) all along, slay 💖✨🎀