linux-kernel - Re: [PATCH linux-next] mm/huge_memory: mark racy access on huge_anon_orders

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Date: Mon, 13 May 2024 18:00:36 +0200
From: David Hildenbrand <david@...hat.com>
To: xu.xin16@....com.cn, akpm@...ux-foundation.org
Cc: willy@...radead.org, shy828301@...il.com, linux-kernel@...r.kernel.org,
 linux-mm@...ck.org, ziy@...dia.com
Subject: Re: [PATCH linux-next] mm/huge_memory: mark racy access on
 huge_anon_orders_always

On 11.05.24 08:44, xu.xin16@....com.cn wrote:
> From: Ran Xiaokai <ran.xiaokai@....com.cn>
> 
> huge_anon_orders_always and huge_anon_orders_always are accessed

"huge_anon_orders_always" mentioned twice.

> lockless, it is better to use the READ_ONCE() wrapper.
> This is not fixing any visible bug, hopefully this can cease some
> KCSAN complains in the future.
> Also do that for huge_anon_orders_madvise.
> 
> Signed-off-by: Ran Xiaokai <ran.xiaokai@....com.cn>
> ---
>   include/linux/huge_mm.h | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> index de0c89105076..6573430ea600 100644
> --- a/include/linux/huge_mm.h
> +++ b/include/linux/huge_mm.h
> @@ -122,8 +122,8 @@ static inline bool hugepage_flags_enabled(void)
>   	 * So we don't need to look at huge_anon_orders_inherit.
>   	 */
>   	return hugepage_global_enabled() ||
> -	       huge_anon_orders_always ||
> -	       huge_anon_orders_madvise;
> +			READ_ONCE(huge_anon_orders_always) ||
> +			READ_ONCE(huge_anon_orders_madvise);

Don't mess up the alignment please.

>   }
> 
>   static inline int highest_order(unsigned long orders)

Acked-by: David Hildenbrand <david@...hat.com>

-- 
Cheers,

David / dhildenb