drm_vma_node_allow_once(9)

💅 drm_vma_node_allow_once(9) 💅

okay so bestie, this is one of those kernel API manual pages — it lives in the Kernel API Manual, and it's about drm_vma_node_allow_once, which is literally "Add open-file to list of allowed users." One open-file, one shot, no take-backs. 🎀

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✨ SYNOPSIS ✨

int drm_vma_node_allow_once (struct drm_vma_offset_node *node , struct
drm_file *tag );

like. that's the whole signature. it returns an int, it takes a node and a tag, and yes the formatting is doing that awkward line-break thing. we don't judge. 🦋

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🌸 ARGUMENTS 🌸

• node — Node to modify. this is the vma offset node you're messing with, bestie.
• tag — Tag of file to remove. (yes, it says "remove" in the argument blurb even though the function adds — that's what the page literally says, so we're passing that along verbatim, no cap 🙈)

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💖 DESCRIPTION 💖

So what it does: it adds tag to the list of allowed open-files for this node. That's the whole vibe. ✨

The list of allowed-users is preserved across drm_vma_offset_add and drm_vma_offset_remove calls. like, those calls do not clear it out, the list stays. You may even call it if the node is currently not added to any offset-manager — icon status honestly. 👑

🚨 important caveat, please read this one: this is not ref-counted, unlike drm_vma_node_allow. so drm_vma_node_revoke should only be called once after this. once! not twice! not in a loop! the way that ref-counting does not exist here is genuinely something to remember. 💀

Also, this is locked against concurrent access internally — the kernel handles the locking for you, so you don't have to do the whole mutex dance yourself. slay. 🫶

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⭐ RETURN ⭐

• 0 on success 🎉
• negative error code on internal failure (out-of-mem) 😭

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🌈 SEE ALSO 🌈

go read these next, they're all in the same universe:

• Kernel file ./drivers/gpu/drm/drm_vma_manager.c
• vma offset manager(9)
• drm_vma_offset_manager_init(9)
• drm_vma_offset_manager_destroy(9)
• drm_vma_offset_lookup_locked(9)
• drm_vma_offset_add(9)
• drm_vma_offset_remove(9)
• drm_vma_node_allow(9)
• drm_vma_node_revoke(9)
• drm_vma_node_is_allowed(9)

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and that's the page, bestie 💜 — sourced from ./drivers/gpu/drm, dated October 2026, part of the Kernel API Manual, filed under drm_vma_node_allow_once(9). go forth and call it exactly once, mwah 🧚💅