Re: [PATCH] mm/vmscan: reclaim every zone in per-node proactive reclaim

[Barry Song]

On Tue, Oct 20, 2026 at 2:50 AM Gregory Price (Meta) <gourry@xxxxxxxxxx> wrote:
>
> user_proactive_reclaim() limits per-node reclaim to
> gfp_zone(GFP_KERNEL), which is ZONE_NORMAL. Proactive reclaim serves no
> allocation, but that limit makes shrink_node() skip every ZONE_MOVABLE
> folio, so writing to /sys/devices/system/node/nodeN/reclaim never
> reclaims a node's movable memory. A movable-only node, such as dax/kmem
> or hotplugged memory onlined movable, reclaims nothing and fails with
> -EAGAIN.
>
> To reproduce, fill a movable-only node with clean page cache and write
> 200M to its nodeN/reclaim: the write fails with -EAGAIN and the page
> cache stays. The same write to a ZONE_NORMAL node frees 200MB.
>
> Scan every zone, as memory.reclaim does.
>
> Fixes: b980077899ea4 ("mm: introduce per-node proactive reclaim interface")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Gregory Price (Meta) <gourry@xxxxxxxxxx>
> ---

Makes a lot of sense to me.

Reviewed-by: Barry Song <baohua@xxxxxxxxxx>