[PATCH 0/3] Allow ZRAM to use any zpool-compatible backend

[Vitaly Wool]

The coming patchset is a new take on the old issue: ZRAM can currently be used only with zsmalloc even though this may not be the optimal combination for some configurations. The previous (unsuccessful) attempt dates back to 2015 [1] and is notable for the heated discussions it has caused.

The patchset in [1] had basically the only goal of enabling ZRAM/zbud combo which had a very narrow use case. Things have changed substantially since then, and now, with z3fold used widely as a zswap backend, I, as the z3fold maintainer, am getting requests to re-interate on making it possible to use ZRAM with any zpool-compatible backend, first of all z3fold.

The preliminary results for this work have been delivered at Linux Plumbers this year [2]. The talk at LPC, though having attracted limited interest, ended in a consensus to continue the work and pursue the goal of decoupling ZRAM from zsmalloc.

The current patchset has been stress tested on arm64 and x86_64 devices, including the Dell laptop I'm writing this message on now, not to mention several QEmu confugirations.

[1] https://lkml.org/lkml/2015/9/14/356
[2] https://linuxplumbersconf.org/event/4/contributions/551/