dax_fault_iter(9)

💅 dax_fault_iter — the Kernel API Manual, bestie edition 🎀

okay so real talk, this page is from the Kernel API Manual (section 9, the kernel-functions girlies) and it's about one little function that does a very specific job. Let me put you on.

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✨ NAME ✨

dax_fault_iter — the common actor that handles pfn insertion in a PTE/PMD fault. yes, that's the whole vibe. it's the shared worker bee that shows up to slot your pfn in, whether you're faulting at the PTE level or the PMD level 💅

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🌸 SYNOPSIS 🌸

vm_fault_t dax_fault_iter (struct vm_fault *vmf , const struct
       iomap_iter *iter , unsigned long *pfnp , struct xa_state *xas , void
       **entry , bool pmd );

it literally returns a vm_fault_t, no cap. take the args, do the thing, hand back your fault status 🫶

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🦋 ARGUMENTS 🦋

six args, she's thorough, we respect it:

• vmf — your vm fault instance. the whole situation you're here to handle, iconic.
• iter — the iomap iter. lowkey essential, it's the iteration context you're working inside.
• pfnp — the pfn that's gonna be returned. it's a pointer, so yes, she writes back. main character energy for real 🔥
• xas — the dax mapping tree of a file. that's your struct xa_state, the map you're navigating 🌈
• entry — an unlocked dax entry that's going to be inserted. unlocked is the key word here, don't forget it 💀
• pmd — the bool that tells you whether this is a pmd fault or not. PTE vs PMD, she's distinguishing, periodt 👑

every argument matters, bestie — don't be out here passing the wrong one and then acting surprised 😭

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👑 SEE ALSO 👑

sibling functions, all from the kernel file ./fs/dax.c — go say hi, they're family:

• enum dax_wake_mode(9)
• dax_folio_reset_order(9)
• dax_lock_folio(9)
• dax_layout_busy_page_range(9)
• dax_iomap_copy_around(9)
• dax_iomap_rw(9)
• dax_iomap_fault(9)
• dax_finish_sync_fault(9)

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and that's the page, bestie! 💖 sourcing this straight from ./fs, dated October 2026 — so go forth, insert your pfns responsibly, and slay ✨🧚🍓