diff --git a/Documentation/ABI/testing/sysfs-devices-memory b/Documentation/ABI/testing/sysfs-devices-memory
index 58dbc592bc57d4ba8692ea0fc54484994b405abb..d8b0f80b9e33cf04938e4c6908c189a1115bbc1a 100644
--- a/Documentation/ABI/testing/sysfs-devices-memory
+++ b/Documentation/ABI/testing/sysfs-devices-memory
@@ -13,13 +13,13 @@ What: /sys/devices/system/memory/memoryX/removable
Date: June 2008
Contact: Badari Pulavarty <pbadari@us.ibm.com>
Description:
- The file /sys/devices/system/memory/memoryX/removable
- indicates whether this memory block is removable or not.
- This is useful for a user-level agent to determine
- identify removable sections of the memory before attempting
- potentially expensive hot-remove memory operation
+ The file /sys/devices/system/memory/memoryX/removable is a
+ legacy interface used to indicated whether a memory block is
+ likely to be offlineable or not. Newer kernel versions return
+ "1" if and only if the kernel supports memory offlining.
Users: hotplug memory remove tools
http://www.ibm.com/developerworks/wikis/display/LinuxP/powerpc-utils
+ lsmem/chmem part of util-linux
What: /sys/devices/system/memory/memoryX/phys_device
Date: September 2008
@@ -44,23 +44,25 @@ Date: September 2008
Contact: Badari Pulavarty <pbadari@us.ibm.com>
Description:
The file /sys/devices/system/memory/memoryX/state
- is read-write. When read, its contents show the
- online/offline state of the memory section. When written,
- root can toggle the the online/offline state of a removable
- memory section (see removable file description above)
- using the following commands::
+ is read-write. When read, it returns the online/offline
+ state of the memory block. When written, root can toggle
+ the online/offline state of a memory block using the following
+ commands::
# echo online > /sys/devices/system/memory/memoryX/state
# echo offline > /sys/devices/system/memory/memoryX/state
- For example, if /sys/devices/system/memory/memory22/removable
- contains a value of 1 and
- /sys/devices/system/memory/memory22/state contains the
- string "online" the following command can be executed by
- by root to offline that section::
-
- # echo offline > /sys/devices/system/memory/memory22/state
-
+ On newer kernel versions, advanced states can be specified
+ when onlining to select a target zone: "online_movable"
+ selects the movable zone. "online_kernel" selects the
+ applicable kernel zone (DMA, DMA32, or Normal). However,
+ after successfully setting one of the advanced states,
+ reading the file will return "online"; the zone information
+ can be obtained via "valid_zones" instead.
+
+ While onlining is unlikely to fail, there are no guarantees
+ that offlining will succeed. Offlining is more likely to
+ succeed if "valid_zones" indicates "Movable".
Users: hotplug memory remove tools
http://www.ibm.com/developerworks/wikis/display/LinuxP/powerpc-utils
@@ -70,8 +72,19 @@ Date: July 2014
Contact: Zhang Zhen <zhenzhang.zhang@huawei.com>
Description:
The file /sys/devices/system/memory/memoryX/valid_zones is
- read-only and is designed to show which zone this memory
- block can be onlined to.
+ read-only.
+
+ For online memory blocks, it returns in which zone memory
+ provided by a memory block is managed. If multiple zones
+ apply (not applicable for hotplugged memory), "None" is returned
+ and the memory block cannot be offlined.
+
+ For offline memory blocks, it returns by which zone memory
+ provided by a memory block can be managed when onlining.
+ The first returned zone ("default") will be used when setting
+ the state of an offline memory block to "online". Only one of
+ the kernel zones (DMA, DMA32, Normal) is applicable for a single
+ memory block.
What: /sys/devices/system/memoryX/nodeY
Date: October 2009
diff --git a/Documentation/admin-guide/mm/memory-hotplug.rst b/Documentation/admin-guide/mm/memory-hotplug.rst
index 245739f55ac7d157021a295656bab74b12a569aa..5307f90738aa9a072209293ee4464ab3592cfafb 100644
--- a/Documentation/admin-guide/mm/memory-hotplug.rst
+++ b/Documentation/admin-guide/mm/memory-hotplug.rst
@@ -162,14 +162,14 @@ Under each memory block, you can see 5 files:
which will be performed on all sections in the block.
``phys_device`` read-only: legacy interface only ever used on s390x to
expose the covered storage increment.
-``removable`` read-only: contains an integer value indicating
- whether the memory block is removable or not
- removable. A value of 1 indicates that the memory
- block is removable and a value of 0 indicates that
- it is not removable. A memory block is removable only if
- every section in the block is removable.
-``valid_zones`` read-only: designed to show which zones this memory block
- can be onlined to.
+``removable`` read-only: legacy interface that indicated whether a memory
+ block was likely to be offlineable or not. Newer kernel
+ versions return "1" if and only if the kernel supports
+ memory offlining.
+``valid_zones`` read-only: designed to show by which zone memory provided by
+ a memory block is managed, and to show by which zone memory
+ provided by an offline memory block could be managed when
+ onlining.
The first column shows it`s default zone.