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SubjectRe: [rfc] increase struct page size?!
Andrew Morton wrote:
> On Sat, 19 May 2007 11:15:01 -0700 William Lee Irwin III <wli@holomorphy.com> wrote:
>
>
>> Much the same holds for the atomic_t's; 32 + PAGE_SHIFT is
>> 44 bits or more, about as much as is possible, and one reference per
>> page per page is not even feasible. Full-length atomic_t's are just
>> not necessary.
>>
>
> You can overflow a page's refcount by mapping it 4G times. That requires
> 32GB of pagetable memory. It's quite feasible with remap_file_pages().
>
But do anybody ever need to do that?
Such an attack is easily thwarted by refusing to map it more
than, say 3G times?

Helge Hafting
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