Comment 1 for bug 1719045

https://github.com/golang/go/blob/964639cc338db650ccadeafb7424bc8ebb2c0f6c/src/runtime/mem_linux.go has the message around the line 138:

                if uintptr(v)&(physPageSize-1) != 0 || n&(physPageSize-1) != 0 {
                                // madvise will round this to any physical page
                                // *covered* by this range, so an unaligned madvise
                                // will release more memory than intended.
                                throw("unaligned sysUnused")