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Subject: Re: [PATCH] mm: memcg: remove direct use of
 __memcg_kmem_uncharge_page
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From: Muchun Song <muchun.song@linux.dev>
In-Reply-To: <20231213130414.353244-1-yosryahmed@google.com>
Date: Wed, 13 Dec 2023 22:26:50 +0800
Cc: Andrew Morton <akpm@linux-foundation.org>,
 Johannes Weiner <hannes@cmpxchg.org>,
 Michal Hocko <mhocko@kernel.org>,
 Roman Gushchin <roman.gushchin@linux.dev>,
 Shakeel Butt <shakeelb@google.com>,
 "Matthew Wilcox (Oracle)" <willy@infradead.org>,
 cgroups@vger.kernel.org,
 linux-mm@kvack.org
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References: <20231213130414.353244-1-yosryahmed@google.com>
To: Yosry Ahmed <yosryahmed@google.com>
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> On Dec 13, 2023, at 21:04, Yosry Ahmed <yosryahmed@google.com> wrote:
> 
> memcg_kmem_uncharge_page() is an inline wrapper around
> __memcg_kmem_uncharge_page() that checks memcg_kmem_online() before
> making the function call. Internally, __memcg_kmem_uncharge_page() has a
> folio_memcg_kmem() check.
> 
> The only direct user of __memcg_kmem_uncharge_page(),
> free_pages_prepare(), checks PageMemcgKmem() before calling it to avoid
> the function call if possible. Move the folio_memcg_kmem() check from
> __memcg_kmem_uncharge_page() to memcg_kmem_uncharge_page() as
> PageMemcgKmem() -- which does the same thing under the hood. Now
> free_pages_prepare() can also use memcg_kmem_uncharge_page().
> 
> No functional change intended.
> 
> Signed-off-by: Yosry Ahmed <yosryahmed@google.com>

Reviewed-by: Muchun Song <songmuchun@bytedance.com>

Thanks