Re: order of matching alloc_pages/free_pages call pairs. Are they always same?

["Joseph A. Knapka" <jknapka@earthlink.net>]

Bulent Abali wrote:
> 
> Is it reasonable to assume that matching
> alloc_pages/free_pages pairs will always have the same order
> as the 2nd argument?
> 
> For example
> pg = alloc_pages( , aorder);   free_pages(pg, forder);
> Is (aorder == forder) always true?
> 
> Or, are there any bizarro drivers etc which will intentionally
> free partial amounts, that is (forder < aorder)?

This would be a somewhat bizarre thing to do, but after thinking
about it a bit, I believe it would work fine - as long as you're
very careful to free blocks with appropriate order and alignment.

I'm not personally aware of any code that actually frees sub-blocks
of allocated blocks, but I expect that when I get around to looking
at the slab allocator (kmalloc(), kfree()) there will be code
in there that does so.

-- Joe


-- Joseph A. Knapka
"If I ever get reincarnated... let me make certain I don't come back
 as a paperclip." -- protagonist, H Murakami's "Hard-boiled Wonderland"
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