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Subject: Re: [PATCH v14 040/138] mm/memcg: Convert mem_cgroup_charge() to take
 a folio
To:     "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        linux-kernel@vger.kernel.org
Cc:     linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
        Christoph Hellwig <hch@lst.de>,
        Michal Hocko <mhocko@kernel.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Vladimir Davydov <vdavydov.dev@gmail.com>
References: <20210715033704.692967-1-willy@infradead.org>
 <20210715033704.692967-41-willy@infradead.org>
From:   Vlastimil Babka <vbabka@suse.cz>
Message-ID: <40a868bf-61dc-1832-4799-ff85018ebcec@suse.cz>
Date:   Wed, 11 Aug 2021 12:54:05 +0200
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On 7/15/21 5:35 AM, Matthew Wilcox (Oracle) wrote:
> Convert all callers of mem_cgroup_charge() to call page_folio() on the
> page they're currently passing in.  Many of them will be converted to
> use folios themselves soon.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> Reviewed-by: Christoph Hellwig <hch@lst.de>


Acked-by: Vlastimil Babka <vbabka@suse.cz>


> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index c2ffad021e09..03283d97b62a 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -6681,10 +6681,9 @@ void mem_cgroup_calculate_protection(struct mem_cgroup *root,
>  			atomic_long_read(&parent->memory.children_low_usage)));
>  }
>  
> -static int __mem_cgroup_charge(struct page *page, struct mem_cgroup *memcg,
> +static int __mem_cgroup_charge(struct folio *folio, struct mem_cgroup *memcg,
>  			       gfp_t gfp)

The git/next version also renames this function to charge_memcg(), why? The new
name doesn't look that internal as the old one. I don't have a strong opinion
but CCing memcg maintainers who might.

>  {
> -	struct folio *folio = page_folio(page);
>  	unsigned int nr_pages = folio_nr_pages(folio);
>  	int ret;
>  
> @@ -6697,27 +6696,27 @@ static int __mem_cgroup_charge(struct page *page, struct mem_cgroup *memcg,
>  
>  	local_irq_disable();
>  	mem_cgroup_charge_statistics(memcg, nr_pages);
> -	memcg_check_events(memcg, page_to_nid(page));
> +	memcg_check_events(memcg, folio_nid(folio));
>  	local_irq_enable();
>  out:
>  	return ret;
>  }
>