linux-kernel - Re: [PATCH 2/3] memcg/hugetlb: Introduce mem_cgroup_charge

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Message-Id: <20241109010307.74840-1-sj@kernel.org>
Date: Fri,  8 Nov 2024 17:03:07 -0800
From: SeongJae Park <sj@...nel.org>
To: Joshua Hahn <joshua.hahnjy@...il.com>
Cc: SeongJae Park <sj@...nel.org>,
	shakeel.butt@...ux.dev,
	hannes@...xchg.org,
	mhocko@...nel.org,
	roman.gushchin@...ux.dev,
	muchun.song@...ux.dev,
	akpm@...ux-foundation.org,
	cgroups@...r.kernel.org,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	kernel-team@...a.com
Subject: Re: [PATCH 2/3] memcg/hugetlb: Introduce mem_cgroup_charge_hugetlb

Hi Joshua,

On Fri, 8 Nov 2024 13:29:45 -0800 Joshua Hahn <joshua.hahnjy@...il.com> wrote:

> This patch introduces mem_cgroup_charge_hugetlb, which combines the
> logic of mem_cgroup{try,commit}_hugetlb. This reduces the footprint of

Nit.  Seems the regular expression is not technically correct?

> memcg in hugetlb code, and also consolidates the error path that memcg
> can take into just one point.
> 
> Signed-off-by: Joshua Hahn <joshua.hahnjy@...il.com>
> 
> ---
>  include/linux/memcontrol.h |  2 ++
>  mm/hugetlb.c               | 34 ++++++++++++----------------------
>  mm/memcontrol.c            | 19 +++++++++++++++++++
>  3 files changed, 33 insertions(+), 22 deletions(-)
[...]
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 97f63ec9c9fb..95ee77fe27af 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -4529,6 +4529,25 @@ int mem_cgroup_hugetlb_try_charge(struct mem_cgroup *memcg, gfp_t gfp,
>  	return 0;
>  }
>  
> +int mem_cgroup_charge_hugetlb(struct folio *folio, gfp_t gfp)

Can we add a kernel-doc comment for this function?  Maybe that for
mem_cgroup_hugetlb_try_charge() can be stolen with only small updates?

> +{
> +	struct mem_cgroup *memcg = get_mem_cgroup_from_current();
> +	int ret = 0;
> +
> +	if (mem_cgroup_disabled() || !memcg_accounts_hugetlb() ||
> +		!memcg || !cgroup_subsys_on_dfl(memory_cgrp_subsys)) {
> +		ret = -EOPNOTSUPP;
> +		goto out;
> +	}
> +
> +	if (charge_memcg(folio, memcg, gfp))
> +		ret = -ENOMEM;
> +
> +out:
> +	mem_cgroup_put(memcg);
> +	return ret;
> +}
> +
>  /**
>   * mem_cgroup_swapin_charge_folio - Charge a newly allocated folio for swapin.
>   * @folio: folio to charge.
> -- 
> 2.43.5


Thanks,
SJ