Re: [PATCH] order>0 page freeing bug

[Andrew Morton]

David Howells <dhowells@xxxxxxxxxx> wrote:
>
> Here's a patch to fix a bug that occurs when an order>0 page allocation is
>  freed.
> 
>  The bug can be demonstrated by this example:
> 
>   (1) if __alloc_page() returns an order 1 allocation, you get back two pages,
>       both with count == 1
> 
>   (2) __free_pages() only decrements the counter on the first page
> 
>   (3) __free_pages_ok() calls free_pages_check() on both pages
> 
>   (4) free_pages_check() complains that the second page is a bad_page because
>       its count is not 0 at that point.

That doesn't sound right - if this was the case, each and every order>0
page freeing would be generating warnings, would it not?

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