My guess is that this is due to some inherent limitations of the Linux kernel swap mechanism ? Possibly so that you can safely disable zswap at runtime (you can

My guess is that this is due to some inherent limitations of the Linux kernel swap mechanism ? Possibly so that you can safely disable zswap at runtime (you can) ? Or quite possibly no one implemented it just yet & writing uncompressed pages is transparently compatible with what normal swapping does.