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SubjectRe: [PATCH] mm/hotplug: remove unnecessary BUG_ON in __offline_pages()
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On Tue, 2013-07-30 at 14:49 +0800, Xishi Qiu wrote:
> I think we can remove "BUG_ON(start_pfn >= end_pfn)" in __offline_pages(),
> because in memory_block_action() "nr_pages = PAGES_PER_SECTION * sections_per_block"
> is always greater than 0.

BUG_ON() is used for checking a condition that should never happen,
unless there is a bug. So, to me, what you described seems to match
with the use of BUG_ON() to prevent a potential bug in the caller.

Thanks,
-Toshi


> memory_block_action()
> offline_pages()
> __offline_pages()
> BUG_ON(start_pfn >= end_pfn)
>
> Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
> ---
> mm/memory_hotplug.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index ca1dd3a..8e333f9 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1472,7 +1472,6 @@ static int __ref __offline_pages(unsigned long start_pfn,
> struct zone *zone;
> struct memory_notify arg;
>
> - BUG_ON(start_pfn >= end_pfn);
> /* at least, alignment against pageblock is necessary */
> if (!IS_ALIGNED(start_pfn, pageblock_nr_pages))
> return -EINVAL;




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