Re: [PATCH] Revert "mm/vmscan: never demote for memcg reclaim"

[Dave Hansen]

On 5/18/22 12:09, Johannes Weiner wrote:
> However, with NUMA balancing now doing tier promotions, demotion is
> part of the page aging process. Global reclaim demotes the coldest
> toptier pages to secondary memory, where their life continues and from
> which they have a chance to get promoted back. Essentially, tiered
> memory systems have an LRU order that spans multiple nodes.

Thanks for the detailed explanation.  Ultimately, this was just intended
as an optimization to make cgroup reclaim more efficient.  But, I agree
that ordering correctness should trump efficiency.

Acked-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>