From: Johannes Weiner <hannes@cmpxchg.org>
To: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Michal Hocko <mhocko@kernel.org>,
Shakeel Butt <shakeel.butt@linux.dev>,
Muchun Song <muchun.song@linux.dev>
Subject: Re: [PATCH v3 3/3] mm: page_counters: initialize usage using ATOMIC_LONG_INIT() macro
Date: Fri, 26 Jul 2024 19:11:10 -0400 [thread overview]
Message-ID: <20240726231110.GF1702603@cmpxchg.org> (raw)
In-Reply-To: <20240726203110.1577216-4-roman.gushchin@linux.dev>
On Fri, Jul 26, 2024 at 08:31:10PM +0000, Roman Gushchin wrote:
> When a page_counter structure is initialized, there is no need to
> use an atomic set operation to initialize the usage counter because
> at this point the structure is not visible to anybody else.
> ATOMIC_LONG_INIT() is what should be used in such cases.
>
> Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev>
> ---
> include/linux/page_counter.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/linux/page_counter.h b/include/linux/page_counter.h
> index cf837d0f8ed1..5da11392b382 100644
> --- a/include/linux/page_counter.h
> +++ b/include/linux/page_counter.h
> @@ -53,7 +53,7 @@ static inline void page_counter_init(struct page_counter *counter,
> struct page_counter *parent,
> bool protection_support)
> {
> - atomic_long_set(&counter->usage, 0);
> + counter->usage = (atomic_long_t)ATOMIC_LONG_INIT(0);
Pretty cool that ATOMIC_LONG_INIT() return value needs a cast to
atomic_long_t! ^_^
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
next prev parent reply other threads:[~2024-07-26 23:11 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-26 20:31 [PATCH v3 0/3] mm: memcg: page counters optimizations Roman Gushchin
2024-07-26 20:31 ` [PATCH v3 1/3] mm: memcg: don't call propagate_protected_usage() needlessly Roman Gushchin
2024-07-26 23:08 ` Johannes Weiner
2024-07-26 20:31 ` [PATCH v3 2/3] mm: page_counters: put page_counter_calculate_protection() under CONFIG_MEMCG Roman Gushchin
2024-07-26 23:09 ` Johannes Weiner
2024-07-26 20:31 ` [PATCH v3 3/3] mm: page_counters: initialize usage using ATOMIC_LONG_INIT() macro Roman Gushchin
2024-07-26 21:37 ` Shakeel Butt
2024-07-26 23:11 ` Johannes Weiner [this message]
2024-07-28 20:54 ` Andrew Morton
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