The memory-notify-based approach aims to handle meory-less nodes, however, it just adds
the complexity of code as pointed by David in thread [1]. The handling of memory-less
nodes is introduced by commit 4faf8d950ec4 ("hugetlb: handle memory hot-plug events").
>From its commit message, we cannot find any necessity of handling this case. So, we can
simply register/unregister sysfs entries in register_node/unregister_node to simlify the
code.
https://lore.kernel.org/linux-mm/60933ffc-b850-976c-78a0-0ee6e0ea9ef0@xxxxxxxxxx/ [1]
Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
---
drivers/base/node.c | 7 +++++--
include/linux/node.h | 5 +++++
mm/hugetlb.c | 37 ++++++++++---------------------------
3 files changed, 20 insertions(+), 29 deletions(-)
diff --git a/drivers/base/node.c b/drivers/base/node.c
index ed391cb09999..cf115d5a9b8a 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -608,10 +608,12 @@ static int register_node(struct node *node, int num)
node->dev.groups = node_dev_groups;
error = device_register(&node->dev);
- if (error)
+ if (error) {
put_device(&node->dev);
- else
+ } else {
+ hugetlb_register_node(node);
compaction_register_node(node);
+ }
return error;
}
@@ -625,6 +627,7 @@ static int register_node(struct node *node, int num)
*/
void unregister_node(struct node *node)
{
+ hugetlb_unregister_node(node);
compaction_unregister_node(node);
node_remove_accesses(node);
node_remove_caches(node);
diff --git a/include/linux/node.h b/include/linux/node.h
index 427a5975cf40..f5d41498c2bf 100644
--- a/include/linux/node.h
+++ b/include/linux/node.h
@@ -138,6 +138,11 @@ extern void unregister_memory_block_under_nodes(struct memory_block *mem_blk);
extern int register_memory_node_under_compute_node(unsigned int mem_nid,
unsigned int cpu_nid,
unsigned access);
+
+#ifdef CONFIG_HUGETLBFS
+void hugetlb_register_node(struct node *node);
+void hugetlb_unregister_node(struct node *node);
+#endif
#else
static inline void node_dev_init(void)
{
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index d0617d64d718..722e862bb6be 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3898,6 +3898,7 @@ static void __init hugetlb_sysfs_init(void)
}
#ifdef CONFIG_NUMA
+static bool hugetlb_initialized __ro_after_init;
/*
* node_hstate/s - associate per node hstate attributes, via their kobjects,
@@ -3953,7 +3954,7 @@ static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
* Unregister hstate attributes from a single node device.
* No-op if no hstate attributes attached.
*/
-static void hugetlb_unregister_node(struct node *node)
+void hugetlb_unregister_node(struct node *node)
{
struct hstate *h;
struct node_hstate *nhs = &node_hstates[node->dev.id];
@@ -3983,19 +3984,22 @@ static void hugetlb_unregister_node(struct node *node)
* Register hstate attributes for a single node device.
* No-op if attributes already registered.
*/
-static int hugetlb_register_node(struct node *node)
+void hugetlb_register_node(struct node *node)
{
struct hstate *h;
struct node_hstate *nhs = &node_hstates[node->dev.id];
int err;
+ if (!hugetlb_initialized)
+ return;
+
if (nhs->hugepages_kobj)
- return 0; /* already allocated */
+ return; /* already allocated */
nhs->hugepages_kobj = kobject_create_and_add("hugepages",
&node->dev.kobj);
if (!nhs->hugepages_kobj)
- return -ENOMEM;
+ return;
for_each_hstate(h) {
err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj,
@@ -4005,28 +4009,9 @@ static int hugetlb_register_node(struct node *node)
pr_err("HugeTLB: Unable to add hstate %s for node %d\n",
h->name, node->dev.id);
hugetlb_unregister_node(node);
- return -ENOMEM;
+ break;
}
}
- return 0;
-}
-
-static int __meminit hugetlb_memory_callback(struct notifier_block *self,
- unsigned long action, void *arg)
-{
- int ret = 0;
- struct memory_notify *mnb = arg;
- int nid = mnb->status_change_nid;
-
- if (nid == NUMA_NO_NODE)
- return NOTIFY_DONE;
-
- if (action == MEM_GOING_ONLINE)
- ret = hugetlb_register_node(node_devices[nid]);
- else if (action == MEM_CANCEL_ONLINE || action == MEM_OFFLINE)
- hugetlb_unregister_node(node_devices[nid]);
-
- return notifier_from_errno(ret);
}
/*
@@ -4038,11 +4023,9 @@ static void __init hugetlb_register_all_nodes(void)
{
int nid;
- get_online_mems();
- hotplug_memory_notifier(hugetlb_memory_callback, 0);
+ hugetlb_initialized = true;
for_each_node_state(nid, N_MEMORY)
hugetlb_register_node(node_devices[nid]);
- put_online_mems();
}
#else /* !CONFIG_NUMA */
--
2.11.0
