Re: [PATCH 6/8] mm/zsmalloc, zswap: Handle objcg charging and lifetime in zsmalloc

[Yosry Ahmed <yosry@kernel.org>]

> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index 067215a6ddcc..88c7cd399261 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -963,6 +963,44 @@ static bool alloc_zspage_objcgs(struct size_class *class, gfp_t gfp,
>         return true;
>  }
>
> +static void zs_charge_objcg(struct zpdesc *zpdesc, struct obj_cgroup *objcg,
> +                           int size, unsigned long offset)
> +{
> +       struct mem_cgroup *memcg;
> +
> +       if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
> +               return;
> +
> +       VM_WARN_ON_ONCE(!(current->flags & PF_MEMALLOC));
> +
> +       /* PF_MEMALLOC context, charging must succeed */
> +       if (obj_cgroup_charge(objcg, GFP_KERNEL, size))
> +               VM_WARN_ON_ONCE(1);
> +
> +       rcu_read_lock();
> +       memcg = obj_cgroup_memcg(objcg);
> +       mod_memcg_state(memcg, MEMCG_ZSWAP_B, size);
> +       mod_memcg_state(memcg, MEMCG_ZSWAPPED, 1);

Zsmalloc should not be updating zswap stats (e.g. in case zram starts
supporting memcg charging).  How about moving the stat updates to
zswap?