Re: [PATCH 2/3] mm/zswap: Implement proactive writeback

[Nhat Pham]

On Mon, May 11, 2026 at 3:52 AM Hao Jia <jiahao.kernel@xxxxxxxxx> wrote:
>
> From: Hao Jia <jiahao1@xxxxxxxxxxx>
>
> Zswap currently writes back pages to backing swap devices reactively,
> triggered either by memory pressure via the shrinker or by the pool
> reaching its size limit. This reactive approach offers no precise
> control over when writeback happens, which can disturb latency-sensitive
> workloads, and it cannot direct writeback at a specific memory cgroup.
> However, there are scenarios where users might want to proactively
> write back cold pages from zswap to the backing swap device, for
> example, to free up memory for other applications or to prepare for
> upcoming memory-intensive workloads.
>
> Therefore, implement a proactive writeback mechanism for zswap by
> adding a new cgroup interface file memory.zswap.proactive_writeback
> within the memory controller.


We already have memory.reclaim, no? Would that not work to create
headroom generally for your use case? Is there a reason why we are
treating zswap memory as special here?