Messages in this thread | | | Date | Mon, 21 May 2007 11:12:59 +0200 | From | Helge Hafting <> | Subject | Re: [rfc] increase struct page size?! |
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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?
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