linux-kernel - Re: [PATCH] mm: clean up obsolete check on space in page->flags

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Date:   Mon, 9 Dec 2019 10:32:37 +0100
From:   David Hildenbrand <david@...hat.com>
To:     Yu Zhao <yuzhao@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Arnd Bergmann <arnd@...db.de>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: clean up obsolete check on space in page->flags

On 08.12.19 19:35, Yu Zhao wrote:
> The check in linux/mm.h was intended to make sure we don't overrun
> page flags. But it's obsolete because it doesn't include
> LAST_CPUPID_WIDTH nor KASAN_TAG_WIDTH.
> 
> Just remove check since we already have it covered in
> linux/page-flags-layout.h (near the end of the file).
> 
> Signed-off-by: Yu Zhao <yuzhao@...gle.com>
> ---
>  include/linux/mm.h | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index c97ea3b694e6..2e7596cce9d8 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -921,10 +921,6 @@ vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf);
>  
>  #define ZONEID_PGSHIFT		(ZONEID_PGOFF * (ZONEID_SHIFT != 0))
>  
> -#if SECTIONS_WIDTH+NODES_WIDTH+ZONES_WIDTH > BITS_PER_LONG - NR_PAGEFLAGS
> -#error SECTIONS_WIDTH+NODES_WIDTH+ZONES_WIDTH > BITS_PER_LONG - NR_PAGEFLAGS
> -#endif
> -
>  #define ZONES_MASK		((1UL << ZONES_WIDTH) - 1)
>  #define NODES_MASK		((1UL << NODES_WIDTH) - 1)
>  #define SECTIONS_MASK		((1UL << SECTIONS_WIDTH) - 1)
> 

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

-- 
Thanks,

David / dhildenb