[rini17]

You mean zswap part of cleancache? But that fell out of kernel completely, no? And zram gained support for backing device.

BTW most of zram tutorials get it wrong, you are supposed to manually mark idle pages and initiate writeback by periodically writing to /sys/block/zramX/idle and /sys/block/zramX/writeback . Otherwise zram will never ever write anything to backing device. It is documented in kernel docs, just that if you expect it to work automatically you might misread it.

And you can convert swap into such backing device, but then you don't do swapon on it (just remove it from fstab) nor it's necesary to format(mkswap) it.