Re: XFS unhappy with large holey loopback and syncs -- [OT] vmalloc 45-bit/32PiB address limit

["Bryan J. Smith" <b.j.smith@xxxxxxxx>]

Andi Kleen <ak@xxxxxxx> wrote:
> For that it should use vmalloc - also no problem because it
> is backed in distributed order 0 4k pages. On 32bit the
vmalloc
> space is a bit limited, but 8MB is still only a small part
of
> it On x86-64 it's VmallocTotal: 34359738367 kB

If I'm reading that correctly, that's 45-bit/32PiB
addressing.  Where does that limit come from?

Is that the limit of Linux's new, 4-level page table logic in
x86-64 (the old 3-level page table being capable of
39-bit/512GiB), or is it something else?

Just curious.


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