[Part3 PATCH v2 0/4] Support hot-remove local pagetable pages.

From: Tang Chen
Date: Thu Jun 13 2013 - 09:39:35 EST

The following patch-set from Yinghai allocates pagetables to local nodes.
v1: https://lkml.org/lkml/2013/3/7/642
v2: https://lkml.org/lkml/2013/3/10/47
v3: https://lkml.org/lkml/2013/4/4/639
v4: https://lkml.org/lkml/2013/4/11/829

Since pagetable pages are used by the kernel, they cannot be offlined.
As a result, they cannot be hot-remove.

This patch fix this problem with the following solution:

1. Introduce a new bootmem type LOCAL_NODE_DATAL, and register local
pagetable pages as LOCAL_NODE_DATAL by setting page->lru.next to
LOCAL_NODE_DATAL, just like we register SECTION_INFO pages.

2. Skip LOCAL_NODE_DATAL pages in offline/online procedures. When the
whole memory block they reside in is offlined, the kernel can
still access the pagetables.
(This changes the semantics of offline/online a little bit.)

3. Do not free LOCAL_NODE_DATAL pages to buddy system because they
were skipped when in offline/online procedures. The memory block
they reside in could have been offlined.

Anyway, this problem should be fixed. Any better idea is welcome.

Change log:
v1 -> v2:
patch2: As suggested by Wu Jianguo, define a macro to check if a page
cantains local node data.
patch4: As suggested by Wu Jianguo, prevent freeing LOCAL_NODE_DATA
pages in free_pagetable() instead of in put_page_bootmem().

Tang Chen (4):
bootmem, mem-hotplug: Register local pagetable pages with
LOCAL_NODE_DATA when freeing bootmem.
mem-hotplug: Skip LOCAL_NODE_DATA pages in memory offline procedure.
mem-hotplug: Skip LOCAL_NODE_DATA pages in memory online procedure.
mem-hotplug: Do not free LOCAL_NODE_DATA pages to buddy system in
hot-remove procedure.

arch/x86/mm/init_64.c | 10 +++++++-
include/linux/memblock.h | 22 +++++++++++++++++
include/linux/memory_hotplug.h | 20 +++++++++++++--
mm/memblock.c | 52 ++++++++++++++++++++++++++++++++++++++++
mm/memory_hotplug.c | 31 +++++++++++++++++++++++
mm/page_alloc.c | 15 ++++++++++-
mm/page_isolation.c | 5 ++++
7 files changed, 149 insertions(+), 6 deletions(-)

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