Re: [PATCH v2 2/2] mm/zswap: Support batch writeback in shrink_memcg()

[Johannes Weiner]

On Fri, Jul 17, 2026 at 04:51:51PM +0800, Hao Jia wrote:
> @@ -1369,7 +1402,7 @@ static void shrink_worker(struct work_struct *w)
>  			goto resched;
>  		}
>  
> -		ret = shrink_memcg(memcg);
> +		ret = shrink_memcg(memcg, NR_ZSWAP_WB_BATCH);
>  		/* drop the extra reference */
>  		mem_cgroup_put(memcg);
>  
> @@ -1493,7 +1526,7 @@ bool zswap_store(struct folio *folio)
>  	objcg = get_obj_cgroup_from_folio(folio);
>  	if (objcg && !obj_cgroup_may_zswap(objcg)) {
>  		memcg = get_mem_cgroup_from_objcg(objcg);
> -		if (shrink_memcg(memcg)) {
> +		if (shrink_memcg(memcg, 1)) {

Why 64 for the global limit but only 1 for the cgroup limit? That
seems arbitrary in multiple ways.

Direct reclaim, kswapd, proactive reclaim, cgroup limit reclaim use
SWAP_CLUSTER_MAX for the batch size near-universally. It's magic too
to be sure, but at least you wouldn't have to make up new magic?

Otherwise, the patch looks good to me.