[PATCH v2 0/8] mm/memory_hotplug: Factor out memory block device handling

[David Hildenbrand <david@redhat.com>]

We only want memory block devices for memory to be onlined/offlined
(add/remove from the buddy). This is required so user space can
online/offline memory and kdump gets notified about newly onlined memory.

Only such memory has the requirement of having to span whole memory blocks.
Let's factor out creation/removal of memory block devices. This helps
to further cleanup arch_add_memory/arch_remove_memory() and to make
implementation of new features easier. E.g. supplying a driver for
memory block devices becomes way easier (so user space is able to
distinguish different types of added memory to properly online it).

Patch 1 makes sure the memory block size granularity is always respected.
Patch 2 implements arch_remove_memory() on s390x. Patch 3 prepares
arch_remove_memory() to be also called without CONFIG_MEMORY_HOTREMOVE.
Patch 4,5 and 6 factor out creation/removal of memory block devices.
Patch 7 gets rid of some unlikely errors that could have happened, not
removing links between memory block devices and nodes, previously brought
up by Oscar.

Did a quick sanity test with DIMM plug/unplug, making sure all devices
and sysfs links properly get added/removed. Compile tested on s390x and
x86-64.

Based on git://git.cmpxchg.org/linux-mmots.git

Next refactoring on my list will be making sure that remove_memory()
will never deal with zones / access "struct pages". Any kind of zone
handling will have to be done when offlining system memory / before
removing device memory. I am thinking about remove_pfn_range_from_zone()",
du undo everything "move_pfn_range_to_zone()" did.

v1 -> v2:
- s390x/mm: Implement arch_remove_memory()
-- remove mapping after "__remove_pages"


David Hildenbrand (8):
  mm/memory_hotplug: Simplify and fix check_hotplug_memory_range()
  s390x/mm: Implement arch_remove_memory()
  mm/memory_hotplug: arch_remove_memory() and __remove_pages() with
    CONFIG_MEMORY_HOTPLUG
  mm/memory_hotplug: Create memory block devices after arch_add_memory()
  mm/memory_hotplug: Drop MHP_MEMBLOCK_API
  mm/memory_hotplug: Remove memory block devices before
    arch_remove_memory()
  mm/memory_hotplug: Make unregister_memory_block_under_nodes() never
    fail
  mm/memory_hotplug: Remove "zone" parameter from
    sparse_remove_one_section

 arch/ia64/mm/init.c            |   2 -
 arch/powerpc/mm/mem.c          |   2 -
 arch/s390/mm/init.c            |  15 +++--
 arch/sh/mm/init.c              |   2 -
 arch/x86/mm/init_32.c          |   2 -
 arch/x86/mm/init_64.c          |   2 -
 drivers/base/memory.c          | 109 +++++++++++++++++++--------------
 drivers/base/node.c            |  27 +++-----
 include/linux/memory.h         |   6 +-
 include/linux/memory_hotplug.h |  12 +---
 include/linux/node.h           |   7 +--
 mm/memory_hotplug.c            |  44 ++++++-------
 mm/sparse.c                    |  10 +--
 13 files changed, 104 insertions(+), 136 deletions(-)

-- 
2.20.1