Re: [PATCH 1/2] mm/vmpressure: skip tree=true accounting on cgroup v2

[Michal Koutný]

Hello Usama.

On Sat, Jun 06, 2026 at 04:41:33AM -0700, Usama Arif <usama.arif@xxxxxxxxx> wrote:
> --- a/mm/vmpressure.c
> +++ b/mm/vmpressure.c
> @@ -246,11 +246,13 @@ void vmpressure(gfp_t gfp, int order, struct mem_cgroup *memcg, bool tree,
>  		return;
>  
>  	/*
> -	 * The in-kernel users only care about the reclaim efficiency
> -	 * for this @memcg rather than the whole subtree, and there
> -	 * isn't and won't be any in-kernel user in a legacy cgroup.
> +	 * Only two combinations have a consumer:
> +	 *   cgroup v2 + tree=false -> in-kernel socket pressure
> +	 *   cgroup v1 + tree=true  -> userspace eventfds (memory.pressure_level)
> +	 * Skip the other two: nothing consumes the result.

This is a good finding, I had some troubles convincing myself that the
v2 has really only the memcg->socket_pressure. I think swapping the
order of the patches would make it easier to comprehend.


Michal

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