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SubjectRe: [PATCH 5/6] Have ia64 use add_active_range() and free_area_init_nodes
KAMEZAWA Hiroyuki wrote:
> On Mon, 15 May 2006 11:19:27 +0100
> Andy Whitcroft <apw@shadowen.org> wrote:
>
>
>>Nick Piggin wrote:
>>
>>>Andy Whitcroft wrote:
>>>
>>>
>>>>Interesting. You are correct there was no config component, at the time
>>>>I didn't have direct evidence that any architecture needed it, only that
>>>>we had an unchecked requirement on zones, a requirement that had only
>>>>recently arrived with the changes to free buddy detection. I note that
>>>
>>>
>>>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.
>
>
> But clean-up/speed-up codes vanished these checks. (I don't know when this occurs)
> Sorry for misses these things.

Heh, sorry to make it sound like it was you who was responsible.

-apw
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