hugetlb: handle memory hot-plug events
Register per node hstate attributes only for nodes with memory. As
suggested by David Rientjes.
With Memory Hotplug, memory can be added to a memoryless node and a node
with memory can become memoryless. Therefore, add a memory on/off-line
notifier callback to [un]register a node's attributes on transition
to/from memoryless state.
N.B., Only tested build, boot, libhugetlbfs regression.
i.e., no memory hotplug testing.
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Reviewed-by: Andi Kleen <andi@firstfloor.org>
Acked-by: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: Adam Litke <agl@us.ibm.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Eric Whitney <eric.whitney@hp.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/vm/hugetlbpage.txt b/Documentation/vm/hugetlbpage.txt
index 6a8e466..bc31636 100644
--- a/Documentation/vm/hugetlbpage.txt
+++ b/Documentation/vm/hugetlbpage.txt
@@ -231,7 +231,8 @@
Per Node Hugepages Attributes
A subset of the contents of the root huge page control directory in sysfs,
-described above, has been replicated under each "node" system device in:
+described above, will be replicated under each the system device of each
+NUMA node with memory in:
/sys/devices/system/node/node[0-9]*/hugepages/
