I've read through the MMU code more than a few times and never noticed this. Who reads past tmpunmap anyways? ;)
Anthony diff -c /sys/src/9/pc/mmu.c /tmp/mmu.c /sys/src/9/pc/mmu.c:934,940 - /tmp/mmu.c:934,940 void* kaddr(ulong pa) { - if(pa > (ulong)-KZERO) + if(pa >= (ulong)-KZERO) panic("kaddr: pa=%#.8lux", pa); return (void*)(pa+KZERO); }