Zswap currently does not do anything special about incompressible pages, it just passes them along to disk. So if the Crypto API can guarantee that compression nevers writes past PAGE_SIZE, the main benefit for zswap would be reducing the buffer size from PAGE_SIZE*2 to PAGE_SIZE. If/when zswap develops handling of incompressible memory (to avoid LRU inversion), I imagine we would handle compression errors and incompressible pages similarly. In both cases we'd store the page as-is and move th LRU along to write more pages to disk. There is no point to fail the reclaim operation in this case, because unlike zram we do have a choice :)
