== BEFORE-FIX (vulnerable) ==
BUG: byte_count = mm_node->size<<PAGE_SHIFT truncates to 0x00000000, num_loops=0 -> VRAM clear SKIPPED
       Freshly allocated VRAM contains previous BO contents -> cross-user leak of GPU memory
== AFTER-FIX ==
FIX: byte_count is uint64_t, num_loops=1024 -> SDMA fill runs correctly