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    SubjectRe: Interaction between Xen and XFS: stray RW mappings
    dean gaudet wrote:
    > On Mon, 15 Oct 2007, Nick Piggin wrote:
    >
    >
    >> Yes, as Dave said, vmap (more specifically: vunmap) is very expensive
    >> because it generally has to invalidate TLBs on all CPUs.
    >>
    >
    > why is that? ignoring 32-bit archs we have heaps of address space
    > available... couldn't the kernel just burn address space and delay global
    > TLB invalidate by some relatively long time (say 1 second)?
    >

    Yes, that's precisely the problem. xfs does delay the unmap, leaving
    stray mappings, which upsets Xen.

    J
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