ib_umem_odp_...dma_and_lock(9)

💖 ib_umem_odp_map_dma_and_lock(9) — a Kernel API Manual moment 💖

okay bestie, welcome to the Kernel API Manual, page ib_umem_odp_...dma_and_lock(9) — yes the name is a whole mouthful, we're abbreviating it in the title because even the manpage authors were like "girl, that's long" 💅 this one's about DMA-mapping userspace memory inside an ODP MR and then locking it. no cap, it's giving "plumbing but make it glam" ✨

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🌸 NAME 🌸

ib_umem_odp_map_dma_and_lock — DMA maps userspace memory in an ODP MR and locks it. that's the whole job description 🫶

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✨ SYNOPSIS ✨

int ib_umem_odp_map_dma_and_lock (struct ib_umem_odp *umem_odp , u64
user_virt , u64 bcnt , u64 access_mask , bool fault );

literally just that one call, bestie. five args, one int coming back at you 🔥

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🎀 ARGUMENTS 🎀

• umem_odp — the umem we're mapping and pinning. main character energy, it's the thing everything else is about 💖
• user_virt — the address we need to map from. like, where in userspace are we grabbing this from, bestie?
• bcnt — the minimal number of bytes to pin and map. heads up though: the mapping might end up bigger because of alignment (alignment said "i'm helping" 😭), and it may also be smaller if pinning or mapping a page errors out. the actual number of pages mapped comes back to you in the return value. iykyk 🌈
• access_mask — a bit mask of the access permissions requested for the given range. bit-mask era 💅
• fault — a bool telling us whether faulting is required for the given range. yes or no, no in-between 🦋

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👑 DESCRIPTION 👑

so here's the vibe: this maps the range you passed in to DMA addresses. iconic. upon success, the ODP MR will be locked so the caller can go finish its device page table update — the lock is basically the "do not disturb, updating my page table" sign on the door 🙈

returns the number of pages mapped on success, and a negative error code on failure. that's the whole contract, fr fr ⭐

if you see a negative number coming back, that's not a page count, bestie — that's the universe telling you something went wrong 💀

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💜 SEE ALSO 💜

• Kernel file ./drivers/infiniband/core/umem_odp.c
• ib_umem_odp_alloc_implicit(9)
• ib_umem_odp_alloc_child(9)
• ib_umem_odp_get(9)

go read those too, they're the friend group 🫶

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aaaand that's the page!! 🎀 living in ./drivers/infiniband/core, dated October 2026 — write that down, bestie, that's the lore ✨ slay, bye 💖