No, if I remember correctly, there was no other way to do what I was doing without using some file on the filesystem as the chunk of memory to be swapped. Calling mmap() on /proc/self/mem allowed one to make a block of memory show up at the zero page and swap it with another with a single system call, instead of copying the block back and forth. It has been at least a decade since I touched that code, so I may be misremembering.