Re: [PATCH 08/10] mm/page_alloc: use get_onbuddy_migratetype() to get buddy list type

From: Joonsoo Kim
Date: Mon Jul 14 2014 - 02:28:25 EST

On Mon, Jul 07, 2014 at 05:57:49PM +0200, Vlastimil Babka wrote:
> On 07/04/2014 09:57 AM, Joonsoo Kim wrote:
> >When isolating free page, what we want to know is which list
> >the page is linked. If it is linked in isolate migratetype buddy list,
> >we can skip watermark check and freepage counting. And if it is linked
> >in CMA migratetype buddy list, we need to fixup freepage counting. For
> >this purpose, get_onbuddy_migratetype() is more fit and cheap than
> >get_pageblock_migratetype(). So use it.
> Hm but you made get_onbuddy_migratetype() work only with
> CONFIG_MEMORY_ISOLATION. And __isolate_free_page is (despite the
> name) not at all limited to CONFIG_MEMORY_ISOLATION.

get_onbuddy_migratetype() is only used for determining whether this
page is on isolate buddy list or not. So if !CONFIG_MEMORY_ISOLATION,
default value of get_onbuddy_migratetype() makes things correct.

But, I should write some code comment.

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