Messages in this thread | | | Date | Fri, 21 Aug 2015 22:31:09 +0300 | From | "Kirill A. Shutemov" <> | Subject | Re: [PATCHv3 4/5] mm: make compound_head() robust |
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On Fri, Aug 21, 2015 at 11:11:27AM -0500, Christoph Lameter wrote: > On Fri, 21 Aug 2015, Kirill A. Shutemov wrote: > > > > Is this really true? For example if it's a slab page, will that page > > > ever be inspected by code which is looking for the PageTail bit? > > > > +Christoph. > > > > What we know for sure is that space is not used in tail pages, otherwise > > it would collide with current compound_dtor. > > Sl*b allocators only do a virt_to_head_page on tail pages.
The question was whether it's safe to assume that the bit 0 is always zero in the word as this bit will encode PageTail().
-- Kirill A. Shutemov
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