Thread (33 messages) flat view 33 messages, 6 authors, 2006-05-23

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

From: Nick Piggin <hidden>
Date: 2006-05-16 00:32:07
Also in: linux-mm, lkml

KAMEZAWA Hiroyuki wrote:
On Mon, 15 May 2006 11:19:27 +0100
Andy Whitcroft [off-list ref] wrote:
quoted
quoted
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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