ttm_bo_vm_reserve(9)

ttm_bo_vm_reserve(9) 💅✨

okay so bestie, welcome to the Kernel API Manual — we're talking about ttm_bo_vm_reserve(9), and it's literally the reserve-a-buffer-object-in-a-retryable-vm-callback moment. No cap, it's giving "kernel plumbing but make it safe to retry." 🫶

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🌸 NAME 🌸

ttm_bo_vm_reserve - Reserve a buffer object in a retryable vm callback

✨ SYNOPSIS ✨

vm_fault_t ttm_bo_vm_reserve (struct ttm_buffer_object *bo , struct
       vm_fault *vmf );

🎀 ARGUMENTS 🎀

• bo — the buffer object, the main character of this whole reserve situation 👑
• vmf — the fault structure that got handed to the callback, so it's basically the receipt for why we're here 🧾

🦋 DESCRIPTION 🦋

okay so vm callbacks like fault and *_mkwrite allow the mmap_lock to be dropped during long waits, and after the wait the callback gets restarted. Why? So other threads using the same virtual memory space can get concurrent access to map and unmap completely unrelated buffer objects. Teamwork, but make it memory management. 🌈

TTM buffer object reservations sometimes wait for the GPU, so bestie, they should be considered long waits. This function reserves the buffer object interruptibly, taking that whole long-wait situation into account. Starvation is avoided by the vm system not allowing too many repeated restarts — the vm system is the bouncer at the club, basically 🕺.

This function is intended to be used in customized fault and _mkwrite handlers. iykyk 💅

⭐ RETURN ⭐

• 0 — success, and the bo was reserved. periodt ✨
• VM_FAULT_RETRY — if blocking wait. 😴
• VM_FAULT_NOPAGE — if blocking wait and retrying was not allowed. 🙈

💖 SEE ALSO 💖

Kernel file:

./drivers/gpu/drm/ttm/ttm_bo_vm.c

also bestie, go look at:

• ttm_bo_vm_fault_reserved(9)
• ttm_bo_access(9)
• ttm_bo_mmap_obj(9)

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This page is living in ./drivers/gpu/drm/ttm, dated October 2026, and it's ttm_bo_vm_reserve(9) — bye bestie, go reserve that buffer object responsibly 💜🦋🎀