People love to do comparisons with highmem_start_page.  However, where
CONFIG_HIGHMEM=y and there is no actual highmem, there's no real page
at *highmem_start_page.

That's usually not a problem, but CONFIG_NONLINEAR is a bit more strict
and catches the bogus address tranlations.

There are about a gillion different ways to find out of a 'struct page'
is highmem or not.  Why not just check page_flags?

Declare page_is_highmem() and use it wherever there used to be a
highmem_start_page comparison.  Then, kill off highmem_start_page.

 memhotplug-dave/arch/i386/mm/discontig.c    |    4 ----
 memhotplug-dave/arch/i386/mm/highmem.c      |    6 +++---
 memhotplug-dave/arch/i386/mm/init.c         |    1 -
 memhotplug-dave/arch/i386/mm/pageattr.c     |    5 +----
 memhotplug-dave/arch/mips/mm/highmem.c      |    6 +++---
 memhotplug-dave/arch/mips/mm/init.c         |    1 -
 memhotplug-dave/arch/ppc/mm/init.c          |    1 -
 memhotplug-dave/arch/sparc/mm/highmem.c     |    2 +-
 memhotplug-dave/arch/sparc/mm/init.c        |    2 --
 memhotplug-dave/arch/um/kernel/mem.c        |    5 -----
 memhotplug-dave/include/asm-ppc/highmem.h   |    6 +++---
 memhotplug-dave/include/asm-sparc/highmem.h |    4 ++--
 memhotplug-dave/include/linux/highmem.h     |   12 ++++++++++--
 memhotplug-dave/mm/memory.c                 |    2 --
 memhotplug-dave/net/core/dev.c              |    2 +-
 15 files changed, 24 insertions(+), 35 deletions(-)

-- Dave