Re: [PATCH 5/6] Have ia64 use add_active_range() and free_area_init_nodes

[Nick Piggin <nickpiggin@yahoo.com.au>]

KAMEZAWA Hiroyuki wrote:

> On Mon, 15 May 2006 11:19:27 +0100
> Andy Whitcroft <apw@shadowen.org> wrote:
>
> > > Recently arrived? Over a year ago with the no-buddy-bitmap patches,
> > > right? Just checking because I that's what I'm assuming broke it...
> > Yep, sorry I forget I was out of the game for 6 months!  And yes that
> > was when the requirements were altered.
> When no-bitmap-buddy patches was included,
>
> 1. bad_range() is not covered by CONFIG_VM_DEBUG. It always worked.
> ==
> static int bad_range(struct zone *zone, struct page *page)
> {
>        if (page_to_pfn(page) >= zone->zone_start_pfn + zone->spanned_pages)
>                return 1;
>        if (page_to_pfn(page) < zone->zone_start_pfn)
>                return 1;
> ==
> And , this code
> ==
>                buddy = __page_find_buddy(page, page_idx, order);
>
>                if (bad_range(zone, buddy))
>                        break;
> ==
>
> checked whether buddy is in zone and guarantees it to have page struct.

Ah, my mistake indeed. Sorry.

> But clean-up/speed-up codes vanished these checks. (I don't know when this occurs)
> Sorry for misses these things.

I think if anything they should be moved into page_is_buddy, however 
page_to_pfn
is expensive on some architectures, so it is something we want to be 
able to opt
out of if we do the correct alignment.

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