linux-kernel - Re: [PATCH] mm: compare MIGRATE

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Date:	Fri, 21 Dec 2012 10:09:02 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Michal Nazarewicz <mina86@...a86.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: compare MIGRATE_ISOLATE selectively

On Thu, Dec 20, 2012 at 04:49:44PM +0100, Michal Nazarewicz wrote:
> On Thu, Dec 20 2012, Minchan Kim wrote:
> > diff --git a/include/linux/page-isolation.h b/include/linux/page-isolation.h
> > index a92061e..4ada4ef 100644
> > --- a/include/linux/page-isolation.h
> > +++ b/include/linux/page-isolation.h
> > @@ -1,6 +1,25 @@
> >  #ifndef __LINUX_PAGEISOLATION_H
> >  #define __LINUX_PAGEISOLATION_H
> >  
> > +#ifdef CONFIG_MEMORY_ISOLATION
> > +static inline bool page_isolated_pageblock(struct page *page)
> > +{
> > +	return get_pageblock_migratetype(page) == MIGRATE_ISOLATE;
> > +}
> > +static inline bool mt_isolated_pageblock(int migratetype)
> > +{
> > +	return migratetype == MIGRATE_ISOLATE;
> > +}
> 
> Perhaps “is_migrate_isolate” to match already existing “is_migrate_cma”?

Good poking. In fact, while I made this patch, I was very tempted by renaming
is_migrate_cma to cma_pageblock.

        is_migrate_cma(mt)

I don't know who start to use "mt" instead of "migratetype" but anyway, it's
not a good idea.

        is_migrate_cma(migratetype)

It's very clear for me because migratetype is per pageblock, we can know the
function works per pageblock unit.

> Especially as the “mt_isolated_pageblock” sound confusing to me, it
> implies that it works on pageblocks which it does not.

-ENOPARSE.

migratetype works on pageblock.
I admit mt is really dirty but I used page_alloc.c already has lots of mt, SIGH.

How about this?

1. Let's change all "mt" with "migratetype" again.
2. use is_migrate_isolate and is_migrate_cma for "migratetype".
3. use is_migrate_isolate_page instead of page_isolated_pageblock for "page".

Okay?

> 
> > +#else
> > +static inline bool page_isolated_pageblock(struct page *page)
> > +{
> > +	return false;
> > +}
> > +static inline bool mt_isolated_pageblock(int migratetype)
> > +{
> > +	return false;
> > +}
> > +#endif
> >  
> >  bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
> >  			 bool skip_hwpoisoned_pages);
> -- 
> Best regards,                                         _     _
> .o. | Liege of Serenely Enlightened Majesty of      o' \,=./ `o
> ..o | Computer Science,  Michał “mina86” Nazarewicz    (o o)
> ooo +----<email/xmpp: mpn@...gle.com>--------------ooO--(_)--Ooo--





-- 
Kind regards,
Minchan Kim
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