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    SubjectRe: [RFCv2 08/10] x86/mm: Make LAM_U48 and mappings above 47-bits mutually exclusive
    On Thu, May 12, 2022 at 03:36:31PM +0200, Thomas Gleixner wrote:
    > On Wed, May 11 2022 at 05:27, Kirill A. Shutemov wrote:
    > > LAM_U48 steals bits above 47-bit for tags and makes it impossible for
    > > userspace to use full address space on 5-level paging machine.
    >
    > > Make these features mutually exclusive: whichever gets enabled first
    > > blocks the othe one.
    >
    > So this patch prevents a mapping above 47bit when LAM48 is enabled, but
    > I fail to spot how an already existing mapping above 47bit would prevent
    > LAM48 from being enabled.
    >
    > Maybe I'm missing something which makes this magically mutually
    > exclusive.

    It is in 09/10. See lam_u48_allowed()

    --
    Kirill A. Shutemov

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