ppc64 oops..

[Paul Mackerras]

Nick Piggin writes:

> I really don't think we've missed PG_reserved. The ZERO_PAGE accounting
> thing may be a problem, but that problem didn't come about due to
> removal of PageReserved, but rather the concurrent removal of ZERO_PAGE
> special casing we had there - it can be reinstated (and a solution for
> 2.6.15 won't be difficult).

Not that I'm any sort of a VM expert, but it seems to me that we need
some sort of way to mark things like the hashed page table on PowerPC
as being "special" memory that is there, but that the VM system should
just completely ignore.  That's what I thought PG_reserved was for,
and IMHO it's useful for that.  For sure we should eliminate the
abuses of PG_reserved, but I don't see that that means we should
eliminate PG_reserved itself.

Paul.