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/
diff --git a/drivers/base/node.c b/drivers/base/node.c
index f502711..9e218a6 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -177,8 +177,8 @@
/*
* hugetlbfs per node attributes registration interface:
* When/if hugetlb[fs] subsystem initializes [sometime after this module],
- * it will register its per node attributes for all nodes online at that
- * time. It will also call register_hugetlbfs_with_node(), below, to
+ * it will register its per node attributes for all online nodes with
+ * memory. It will also call register_hugetlbfs_with_node(), below, to
* register its attribute registration functions with this node driver.
* Once these hooks have been initialized, the node driver will call into
* the hugetlb module to [un]register attributes for hot-plugged nodes.
@@ -188,7 +188,8 @@
static inline void hugetlb_register_node(struct node *node)
{
- if (__hugetlb_register_node)
+ if (__hugetlb_register_node &&
+ node_state(node->sysdev.id, N_HIGH_MEMORY))
__hugetlb_register_node(node);
}
@@ -233,6 +234,7 @@
sysdev_create_file(&node->sysdev, &attr_distance);
scan_unevictable_register_node(node);
+
hugetlb_register_node(node);
}
return error;
@@ -254,7 +256,7 @@
sysdev_remove_file(&node->sysdev, &attr_distance);
scan_unevictable_unregister_node(node);
- hugetlb_unregister_node(node);
+ hugetlb_unregister_node(node); /* no-op, if memoryless node */
sysdev_unregister(&node->sysdev);
}
@@ -384,8 +386,45 @@
}
return err;
}
+
+/*
+ * Handle per node hstate attribute [un]registration on transistions
+ * to/from memoryless state.
+ */
+
+static int node_memory_callback(struct notifier_block *self,
+ unsigned long action, void *arg)
+{
+ struct memory_notify *mnb = arg;
+ int nid = mnb->status_change_nid;
+
+ switch (action) {
+ case MEM_ONLINE: /* memory successfully brought online */
+ if (nid != NUMA_NO_NODE)
+ hugetlb_register_node(&node_devices[nid]);
+ break;
+ case MEM_OFFLINE: /* or offline */
+ if (nid != NUMA_NO_NODE)
+ hugetlb_unregister_node(&node_devices[nid]);
+ break;
+ case MEM_GOING_ONLINE:
+ case MEM_GOING_OFFLINE:
+ case MEM_CANCEL_ONLINE:
+ case MEM_CANCEL_OFFLINE:
+ default:
+ break;
+ }
+
+ return NOTIFY_OK;
+}
#else
static int link_mem_sections(int nid) { return 0; }
+
+static inline int node_memory_callback(struct notifier_block *self,
+ unsigned long action, void *arg)
+{
+ return NOTIFY_OK;
+}
#endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
int register_one_node(int nid)
@@ -499,13 +538,17 @@
return err;
}
+#define NODE_CALLBACK_PRI 2 /* lower than SLAB */
static int __init register_node_type(void)
{
int ret;
ret = sysdev_class_register(&node_class);
- if (!ret)
+ if (!ret) {
ret = node_states_init();
+ hotplug_memory_notifier(node_memory_callback,
+ NODE_CALLBACK_PRI);
+ }
/*
* Note: we're not going to unregister the node class if we fail
