memory-hotplug: add sysfs valid_zones attribute
Currently memory-hotplug has two limits:
1. If the memory block is in ZONE_NORMAL, you can change it to
ZONE_MOVABLE, but this memory block must be adjacent to ZONE_MOVABLE.
2. If the memory block is in ZONE_MOVABLE, you can change it to
ZONE_NORMAL, but this memory block must be adjacent to ZONE_NORMAL.
With this patch, we can easy to know a memory block can be onlined to
which zone, and don't need to know the above two limits.
Updated the related Documentation.
[akpm@linux-foundation.org: use conventional comment layout]
[akpm@linux-foundation.org: fix build with CONFIG_MEMORY_HOTREMOVE=n]
[akpm@linux-foundation.org: remove unused local zone_prev]
Signed-off-by: Zhang Zhen <zhenzhang.zhang@huawei.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Wang Nan <wangnan0@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/memory-hotplug.txt b/Documentation/memory-hotplug.txt
index 45134dc..ea03abf 100644
--- a/Documentation/memory-hotplug.txt
+++ b/Documentation/memory-hotplug.txt
@@ -155,6 +155,7 @@
/sys/devices/system/memory/memoryXXX/phys_device
/sys/devices/system/memory/memoryXXX/state
/sys/devices/system/memory/memoryXXX/removable
+/sys/devices/system/memory/memoryXXX/valid_zones
'phys_index' : read-only and contains memory block id, same as XXX.
'state' : read-write
@@ -170,6 +171,15 @@
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.
+ The first column shows it's default zone.
+ "memory6/valid_zones: Normal Movable" shows this memoryblock
+ can be onlined to ZONE_NORMAL by default and to ZONE_MOVABLE
+ by online_movable.
+ "memory7/valid_zones: Movable Normal" shows this memoryblock
+ can be onlined to ZONE_MOVABLE by default and to ZONE_NORMAL
+ by online_kernel.
NOTE:
These directories/files appear after physical memory hotplug phase.
@@ -408,7 +418,6 @@
- allowing memory hot-add to ZONE_MOVABLE. maybe we need some switch like
sysctl or new control file.
- showing memory block and physical device relationship.
- - showing memory block is under ZONE_MOVABLE or not
- test and make it better memory offlining.
- support HugeTLB page migration and offlining.
- memmap removing at memory offline.