On Mon, Aug 15, 2022 at 01:13:27AM -0600, Yu Zhao wrote: > + for (i = pmd_index(start), addr = start; addr != end; i++, addr = next) { > + pmd_t val = pmd_read_atomic(pmd + i); > + > + /* for pmd_read_atomic() */ > + barrier(); Please clarify the above. This is an entirely inadequate ordering comment. > + > + next = pmd_addr_end(addr, end);