MMU NOTIFIER(9)

💅 MMU Notifier 💅

okay bestie, this little icon lives in the Kernel API Manual, and it’s here to explain how coherent userptr handling works ✨ For coherent userptr handling, it registers an MMU notifier to inform the driver about updates on the page tables of a process. no cap, that’s the whole vibe 👑

When somebody tries to invalidate the page tables, we block the update until all operations on the pages in question are completed 🫶 Then those pages are marked as accessed and also dirty if it wasn’t a read only access. periodt 💅

New command submissions using the userptrs in question are delayed until all page table invalidation are completed and we once more see a coherent process address space 🌸 literally the coherence check of it all.

🔍 SEE ALSO 🔍

• Kernel file ./drivers/gpu/drm/amd/amdgpu/amdgpu_hmm.c
• amdgpu_hmm_invalidate_gfx(9)
• amdgpu_hmm_invalidate_hsa(9)
• amdgpu_hmm_register(9)
• amdgpu_hmm_unregister(9)
• amdgpu_hmm_range_valid(9)
• amdgpu_hmm_range_alloc(9)
• amdgpu_hmm_range_free(9)

mwah 💋 that’s the page, bestie — source/version: ./drivers/gpu/drm/amd/amdgpu, dated October 2026 🎀🦋