[PATCH v5 0/5] sparse_init rewrite

[Pavel Tatashin <pasha.tatashin@oracle.com>]

Changelog:
v5 - v4
	- Fixed the issue that was reported on ppc64 when
	  CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER is removed
	- Consolidated the new buffer allocation between vmemmap
	  and non-vmemmap variants of sparse layout.
	- Removed all review-by comments, because I had to do
	  significant amount of changes compared to previous version
	  and need another round of review.
	- I also would appreciate if those who reported problems with
	  PPC64 could test this change.
v4 - v3
	- Addressed comments from Dave Hansen
v3 - v1
	- Fixed two issues found by Baoquan He
v1 - v2
	- Addressed comments from Oscar Salvador

In sparse_init() we allocate two large buffers to temporary hold usemap and
memmap for the whole machine. However, we can avoid doing that if we
changed sparse_init() to operated on per-node bases instead of doing it on
the whole machine beforehand.

As shown by Baoquan
http://lkml.kernel.org/r/20180628062857.29658-1-bhe@redhat.com

The buffers are large enough to cause machine stop to boot on small memory
systems.

Another benefit of these changes is that they also obsolete
CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER.

Pavel Tatashin (5):
  mm/sparse: abstract sparse buffer allocations
  mm/sparse: use the new sparse buffer functions in non-vmemmap
  mm/sparse: move buffer init/fini to the common place
  mm/sparse: add new sparse_init_nid() and sparse_init()
  mm/sparse: delete old sprase_init and enable new one

 include/linux/mm.h  |   7 +-
 mm/Kconfig          |   4 -
 mm/sparse-vmemmap.c |  59 +--------
 mm/sparse.c         | 300 +++++++++++++++-----------------------------
 4 files changed, 105 insertions(+), 265 deletions(-)

-- 
2.18.0