Re: [PATCH 2 of 4] hotplug-memory: adding non-section-alignedmemory is bad

[KAMEZAWA Hiroyuki]

On Thu, 27 Mar 2008 17:28:38 -0700
Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -784,6 +784,9 @@
>  #define PAGES_PER_SECTION       (1UL << PFN_SECTION_SHIFT)
>  #define PAGE_SECTION_MASK	(~(PAGES_PER_SECTION-1))
>  
> +#define SECTION_SIZE		(1UL << SECTION_SIZE_BITS)
> +#define SECTION_SIZE_MASK	(SECTION_SIZE - 1)
> +
>  #define SECTION_BLOCKFLAGS_BITS \
>  	((1UL << (PFN_SECTION_SHIFT - pageblock_order)) * NR_PAGEBLOCK_BITS)
>  
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -300,6 +300,11 @@
>  	int ret;
>  	u64 start = res->start;
>  	u64 size = res->end - res->start + 1;
> +
> +	/* Adding non-section-aligned memory will give unexpected
> +	   and unintuitive results. */
> +	WARN_ON((start & SECTION_SIZE_MASK) != 0);
> +	WARN_ON((size & SECTION_SIZE_MASK) != 0);
>  
Why just WARNING ? not BUG_ON?

Thanks,
-Kame

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