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SubjectRe: how does kernel get the "current" task struct?
Jamie Lokier wrote:
> That's what I said. E.g., you have a zone starting at 4k that's 32k
> long. You initialise the allocator by calling free_page on each page.
> The buddy structure ends up looking like this:
>
> 4k @ 4k
> 16k @ 8k
> 4k @ 24k
>
No. It could end up like this, but it doesn't end up like this right now
:-(

__free_pages_ok() aligns the buddy algorithm to "page - mem_map +
zone->offset".

This means that 44k starting at 4k will end up as

32k @ 4k x = 0
8k @ 36k x = 8
4k @ 44k x = 10

where x = (page-mem_map+zone->offset)/sizeof(struct page).

I doubt that this is a problem, because zones are aligned on MB
boundaries, but perhaps this could become a problem for a weird
DISCONTIGMEM embedded system.

--
Manfred

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