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[Xen-devel] [PATCH v6 0/2] memory-hotplug: add automatic onlining policy for the newly added memory

Changes since v5:
Patch 1:
- Mention possible failures during automatic onlining in memory-hotplug.txt
  [David Rientjes]
- Add Daniel's Reviewed-by: (hope it stands)

- Change the last 'domU' -> 'target domain' in Kconfig [Daniel Kiper]
- Add Daniel's Reviewed-by:
- Add David's Acked-by:

Original description:

Currently, all newly added memory blocks remain in 'offline' state unless
someone onlines them, some linux distributions carry special udev rules

SUBSYSTEM=="memory", ACTION=="add", ATTR{state}=="offline", ATTR{state}="online"

to make this happen automatically. This is not a great solution for virtual
machines where memory hotplug is being used to address high memory pressure
situations as such onlining is slow and a userspace process doing this
(udev) has a chance of being killed by the OOM killer as it will probably
require to allocate some memory.

Introduce default policy for the newly added memory blocks in
/sys/devices/system/memory/auto_online_blocks file with two possible
values: "offline" which preserves the current behavior and "online" which
causes all newly added memory blocks to go online as soon as they're added.
The default is "offline".

Vitaly Kuznetsov (2):
  memory-hotplug: add automatic onlining policy for the newly added
  xen_balloon: support memory auto onlining policy

 Documentation/memory-hotplug.txt | 23 ++++++++++++++++++++---
 drivers/base/memory.c            | 34 +++++++++++++++++++++++++++++++++-
 drivers/xen/Kconfig              | 23 +++++++++++++++--------
 drivers/xen/balloon.c            | 11 ++++++++++-
 include/linux/memory.h           |  3 +++
 include/linux/memory_hotplug.h   |  4 +++-
 mm/memory_hotplug.c              | 17 +++++++++++++++--
 7 files changed, 99 insertions(+), 16 deletions(-)


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