linux-kernel - Re: [PATCH] mm/x86: Use SWP_TYPE

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Message-ID: <9b018e35-de8e-76ab-8f7b-c7b23e640217@redhat.com>
Date:   Wed, 3 Aug 2022 15:18:13 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Peter Xu <peterx@...hat.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Cc:     Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] mm/x86: Use SWP_TYPE_BITS in 3-level swap macros

On 03.08.22 02:37, Peter Xu wrote:
> Replace all the magic "5" with the macro.
> 
> Signed-off-by: Peter Xu <peterx@...hat.com>
> ---
>  arch/x86/include/asm/pgtable-3level.h | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/include/asm/pgtable-3level.h b/arch/x86/include/asm/pgtable-3level.h
> index e896ebef8c24..28421a887209 100644
> --- a/arch/x86/include/asm/pgtable-3level.h
> +++ b/arch/x86/include/asm/pgtable-3level.h
> @@ -256,10 +256,10 @@ static inline pud_t native_pudp_get_and_clear(pud_t *pudp)
>  /* We always extract/encode the offset by shifting it all the way up, and then down again */
>  #define SWP_OFFSET_SHIFT	(SWP_OFFSET_FIRST_BIT + SWP_TYPE_BITS)
>  
> -#define MAX_SWAPFILES_CHECK() BUILD_BUG_ON(MAX_SWAPFILES_SHIFT > 5)
> -#define __swp_type(x)			(((x).val) & 0x1f)
> -#define __swp_offset(x)			((x).val >> 5)
> -#define __swp_entry(type, offset)	((swp_entry_t){(type) | (offset) << 5})
> +#define MAX_SWAPFILES_CHECK() BUILD_BUG_ON(MAX_SWAPFILES_SHIFT > SWP_TYPE_BITS)
> +#define __swp_type(x)			(((x).val) & ((1UL << SWP_TYPE_BITS) - 1))
> +#define __swp_offset(x)			((x).val >> SWP_TYPE_BITS)
> +#define __swp_entry(type, offset)	((swp_entry_t){(type) | (offset) << SWP_TYPE_BITS})
>  
>  /*
>   * Normally, __swp_entry() converts from arch-independent swp_entry_t to

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

-- 
Thanks,

David / dhildenb