Series comparison

-[PATCH v6 0/3] Enhance sysfs handling for memory hotplug in weighted interleave
+[PATCH v7 0/3] Enhance sysfs handling for memory hotplug in weighted interleave
 ...
    - Hooks into memory hotplug notifier for runtime updates.
 These patches have been tested under CXL-based memory configurations,
 including hotplug scenarios, to ensure proper behavior and stability.
- mm/mempolicy.c | 194 ++++++++++++++++++++++++++++++++-----------------
+ mm/mempolicy.c | 193 +++++++++++++++++++++++++++++++------------------
-file changed, 126 insertions(+), 68 deletions(-)
+file changed, 124 insertions(+), 69 deletions(-)
-base-commit: 38fec10eb60d687e30c8c6b5420d86e8149f7557
+base-commit: 0af2f6be1b4281385b618cb86ad946eded089ac8
 --
 .34.1

-[PATCH v6 1/3] mm/mempolicy: Fix memory leaks in weighted interleave sysfs
+[PATCH v7 1/3] mm/mempolicy: Fix memory leaks in weighted interleave sysfs
 ...
 Signed-off-by: Rakie Kim <rakie.kim@sk.com>
 Signed-off-by: Honggyu Kim <honggyu.kim@sk.com>
 Signed-off-by: Yunjeong Mun <yunjeong.mun@sk.com>
 Reviewed-by: Gregory Price <gourry@gourry.net>
 ---
- mm/mempolicy.c | 64 +++++++++++++++++++++++++++-----------------------
+ mm/mempolicy.c | 66 ++++++++++++++++++++++++--------------------------
-file changed, 34 insertions(+), 30 deletions(-)
+file changed, 32 insertions(+), 34 deletions(-)
 diff --git a/mm/mempolicy.c b/mm/mempolicy.c
 index XXXXXXX..XXXXXXX 100644
 --- a/mm/mempolicy.c
 +++ b/mm/mempolicy.c
 ...
  static const struct kobj_type wi_ktype = {
 @@ -XXX,XX +XXX,XX @@ static int add_weighted_interleave_group(struct kobject *root_kobj)
      struct kobject *wi_kobj;
      int nid, err;
--    wi_kobj = kzalloc(sizeof(struct kobject), GFP_KERNEL);
--    if (!wi_kobj)
 +    node_attrs = kcalloc(nr_node_ids, sizeof(struct iw_node_attr *),
 +                 GFP_KERNEL);
 +    if (!node_attrs)
++        return -ENOMEM;
++
+     wi_kobj = kzalloc(sizeof(struct kobject), GFP_KERNEL);
+-    if (!wi_kobj)
++    if (!wi_kobj) {
++        kfree(node_attrs);
          return -ENOMEM;
-+    wi_kobj = kzalloc(sizeof(struct kobject), GFP_KERNEL);
-+    if (!wi_kobj) {
-+        err = -ENOMEM;
-+        goto node_out;
 +    }
-+
      err = kobject_init_and_add(wi_kobj, &wi_ktype, root_kobj,
                     "weighted_interleave");
-     if (err) {
+-    if (err) {
 -        kfree(wi_kobj);
 -        return err;
-+        kobject_put(wi_kobj);
+-    }
-+        goto err_out;
++    if (err)
-     }
++        goto err_put_kobj;
      for_each_node_state(nid, N_POSSIBLE) {
-@@ -XXX,XX +XXX,XX @@ static int add_weighted_interleave_group(struct kobject *root_kobj)
+         err = add_weight_node(nid, wi_kobj);
-             break;
+         if (err) {
              pr_err("failed to add sysfs [node%d]\n", nid);
 -            break;
 +            goto err_del_kobj;
          }
      }
 -    if (err)
-+    if (err) {
+-        kobject_put(wi_kobj);
 +        kobject_del(wi_kobj);
          kobject_put(wi_kobj);
 +        goto err_out;
 +    }
 +
      return 0;
 +
-+node_out:
++err_del_kobj:
-+    kfree(node_attrs);
++    kobject_del(wi_kobj);
-+err_out:
++err_put_kobj:
 +    kobject_put(wi_kobj);
 +    return err;
  }
  static void mempolicy_kobj_release(struct kobject *kobj)
 @@ -XXX,XX +XXX,XX @@ static void mempolicy_kobj_release(struct kobject *kobj)
 ...
      err = kobject_init_and_add(mempolicy_kobj, &mempolicy_ktype, mm_kobj,
                     "mempolicy");
      if (err)
 -        goto node_out;
-+        goto err_out;
++        goto err_put_kobj;
      err = add_weighted_interleave_group(mempolicy_kobj);
 -    if (err) {
 -        pr_err("mempolicy sysfs structure failed to initialize\n");
 -        kobject_put(mempolicy_kobj);
 -        return err;
 -    }
 +    if (err)
-+        goto err_del;
++        goto err_del_kobj;
 -    return err;
 -node_out:
 -    kfree(node_attrs);
 -mempol_out:
 -    kfree(mempolicy_kobj);
+-err_out:
+-    pr_err("failed to add mempolicy kobject to the system\n");
 +    return 0;
 +
-+err_del:
++err_del_kobj:
 +    kobject_del(mempolicy_kobj);
- err_out:
++err_put_kobj:
 -    pr_err("failed to add mempolicy kobject to the system\n");
 +    kobject_put(mempolicy_kobj);
      return err;
  }
 --
 .34.1

-[PATCH v6 2/3] mm/mempolicy: Prepare weighted interleave sysfs for memory hotplug
+[PATCH v7 2/3] mm/mempolicy: Prepare weighted interleave sysfs for memory hotplug
 ...
 Signed-off-by: Rakie Kim <rakie.kim@sk.com>
 Signed-off-by: Honggyu Kim <honggyu.kim@sk.com>
 Signed-off-by: Yunjeong Mun <yunjeong.mun@sk.com>
 Reviewed-by: Gregory Price <gourry@gourry.net>
 ---
- mm/mempolicy.c | 73 ++++++++++++++++++++++----------------------------
+ mm/mempolicy.c | 61 ++++++++++++++++++++++++--------------------------
-file changed, 32 insertions(+), 41 deletions(-)
+file changed, 29 insertions(+), 32 deletions(-)
 diff --git a/mm/mempolicy.c b/mm/mempolicy.c
 index XXXXXXX..XXXXXXX 100644
 --- a/mm/mempolicy.c
 +++ b/mm/mempolicy.c
 ...
 +    wi_group->nattrs[nid] = node_attr;
      return 0;
  }
 -static int add_weighted_interleave_group(struct kobject *root_kobj)
-+static int add_weighted_interleave_group(struct kobject *mempolicy_kobj)
++static int __init add_weighted_interleave_group(struct kobject *mempolicy_kobj)
  {
 -    struct kobject *wi_kobj;
      int nid, err;
 -    node_attrs = kcalloc(nr_node_ids, sizeof(struct iw_node_attr *),
 -                 GFP_KERNEL);
 -    if (!node_attrs)
 +    wi_group = kzalloc(struct_size(wi_group, nattrs, nr_node_ids),
-+            GFP_KERNEL);
++               GFP_KERNEL);
 +    if (!wi_group)
          return -ENOMEM;
 -    wi_kobj = kzalloc(sizeof(struct kobject), GFP_KERNEL);
 -    if (!wi_kobj) {
--        err = -ENOMEM;
+-        kfree(node_attrs);
--        goto node_out;
+-        return -ENOMEM;
 -    }
 -
 -    err = kobject_init_and_add(wi_kobj, &wi_ktype, root_kobj,
 +    err = kobject_init_and_add(&wi_group->wi_kobj, &wi_ktype, mempolicy_kobj,
                     "weighted_interleave");
--    if (err) {
+     if (err)
--        kobject_put(wi_kobj);
+         goto err_put_kobj;
 +    if (err)
          goto err_out;
 -    }
      for_each_node_state(nid, N_POSSIBLE) {
 -        err = add_weight_node(nid, wi_kobj);
 +        err = sysfs_wi_node_add(nid);
          if (err) {
              pr_err("failed to add sysfs [node%d]\n", nid);
--            break;
+             goto err_del_kobj;
-+            goto err_del;
+@@ -XXX,XX +XXX,XX @@ static int add_weighted_interleave_group(struct kobject *root_kobj)
          }
      }
 -    if (err) {
 -        kobject_del(wi_kobj);
 -        kobject_put(wi_kobj);
 -        goto err_out;
 -    }
      return 0;
--node_out:
+ err_del_kobj:
--    kfree(node_attrs);
+-    kobject_del(wi_kobj);
 +err_del:
 +    kobject_del(&wi_group->wi_kobj);
- err_out:
+ err_put_kobj:
 -    kobject_put(wi_kobj);
 +    kobject_put(&wi_group->wi_kobj);
      return err;
  }
 --
 .34.1

-[PATCH v6 3/3] mm/mempolicy: Support memory hotplug in weighted interleave
+[PATCH v7 3/3] mm/mempolicy: Support memory hotplug in weighted interleave
 ...
 events.
 Signed-off-by: Rakie Kim <rakie.kim@sk.com>
 Signed-off-by: Honggyu Kim <honggyu.kim@sk.com>
 Signed-off-by: Yunjeong Mun <yunjeong.mun@sk.com>
+Reviewed-by: Oscar Salvador <osalvador@suse.de>
 ---
- mm/mempolicy.c | 109 ++++++++++++++++++++++++++++++++++++++-----------
+ mm/mempolicy.c | 106 ++++++++++++++++++++++++++++++++++++++-----------
-file changed, 86 insertions(+), 23 deletions(-)
+file changed, 83 insertions(+), 23 deletions(-)
 diff --git a/mm/mempolicy.c b/mm/mempolicy.c
 index XXXXXXX..XXXXXXX 100644
 --- a/mm/mempolicy.c
 +++ b/mm/mempolicy.c
 ...
 +    int err;
 +    struct memory_notify *arg = data;
 +    int nid = arg->status_change_nid;
 +
 +    if (nid < 0)
-+        goto notifier_end;
++        return NOTIFY_OK;
 +
 +    switch(action) {
 +    case MEM_ONLINE:
 +        err = sysfs_wi_node_add(nid);
-+        if (err) {
++        if (err)
 +            pr_err("failed to add sysfs [node%d]\n", nid);
-+            return NOTIFY_BAD;
-+        }
 +        break;
 +    case MEM_OFFLINE:
 +        sysfs_wi_node_delete(nid);
 +        break;
 +    }
 +
-+notifier_end:
 +    return NOTIFY_OK;
  }
- static int add_weighted_interleave_group(struct kobject *mempolicy_kobj)
+ static int __init add_weighted_interleave_group(struct kobject *mempolicy_kobj)
-@@ -XXX,XX +XXX,XX @@ static int add_weighted_interleave_group(struct kobject *mempolicy_kobj)
+@@ -XXX,XX +XXX,XX @@ static int __init add_weighted_interleave_group(struct kobject *mempolicy_kobj)
-             GFP_KERNEL);
+                GFP_KERNEL);
      if (!wi_group)
          return -ENOMEM;
 +    mutex_init(&wi_group->kobj_lock);
      err = kobject_init_and_add(&wi_group->wi_kobj, &wi_ktype, mempolicy_kobj,
                     "weighted_interleave");
      if (err)
-         goto err_out;
+         goto err_put_kobj;
 -    for_each_node_state(nid, N_POSSIBLE) {
 +    for_each_online_node(nid) {
 +        if (!node_state(nid, N_MEMORY))
 +            continue;
 +
          err = sysfs_wi_node_add(nid);
          if (err) {
              pr_err("failed to add sysfs [node%d]\n", nid);
-@@ -XXX,XX +XXX,XX @@ static int add_weighted_interleave_group(struct kobject *mempolicy_kobj)
+@@ -XXX,XX +XXX,XX @@ static int __init add_weighted_interleave_group(struct kobject *mempolicy_kobj)
          }
      }
 +    hotplug_memory_notifier(wi_node_notifier, DEFAULT_CALLBACK_PRI);
      return 0;
- err_del:
+ err_del_kobj:
 --
 .34.1

The following patch series enhances the weighted interleave policy in the
memory management subsystem by improving sysfs handling, fixing memory leaks,
and introducing dynamic sysfs updates for memory hotplug support.

### Background
The weighted interleave policy distributes memory allocations across multiple
NUMA nodes based on their performance weight, thereby optimizing memory
bandwidth utilization. The weight values are configured through sysfs.

Previously, sysfs entries for weighted interleave were managed statically
at initialization. This led to several issues:
- Memory Leaks: Improper `kobject` teardown caused memory leaks
  when initialization failed or when nodes were removed.
- Lack of Dynamic Updates: Sysfs attributes were created only during
  initialization, preventing nodes added at runtime from being recognized.
- Handling of Unusable Nodes: Sysfs entries were generated for all
  possible nodes (`N_POSSIBLE`), including memoryless or unavailable nodes,
  leading to sysfs entries for unusable nodes and potential
  misconfigurations.

### Patch Overview
1. [PATCH 1/3] mm/mempolicy: Fix memory leaks in weighted interleave sysfs
   - Ensures proper cleanup of `kobject` allocations.
   - Adds `kobject_del()` before `kobject_put()` to clean up sysfs state correctly.
   - Prevents memory/resource leaks and improves teardown behavior.

2. [PATCH 2/3] mm/mempolicy: Prepare weighted interleave sysfs for memory hotplug
   - Refactors static sysfs layout into a new `sysfs_wi_group` structure.
   - Makes per-node sysfs attributes accessible to external modules.
   - Lays groundwork for future hotplug support by enabling runtime modification.

3. [PATCH 3/3] mm/mempolicy: Support memory hotplug in weighted interleave
   - Dynamically adds/removes sysfs entries when nodes are online/offline.
   - Limits sysfs creation to nodes with memory, avoiding unusable node entries.
   - Hooks into memory hotplug notifier for runtime updates.

These patches have been tested under CXL-based memory configurations,
including hotplug scenarios, to ensure proper behavior and stability.

mm/mempolicy.c | 194 ++++++++++++++++++++++++++++++++-----------------
 1 file changed, 126 insertions(+), 68 deletions(-)

base-commit: 38fec10eb60d687e30c8c6b5420d86e8149f7557
-- 
2.34.1

Memory leaks occurred when removing sysfs attributes for weighted
interleave. Improper kobject deallocation led to unreleased memory
when initialization failed or when nodes were removed.

This patch resolves the issue by replacing unnecessary `kfree()`
calls with proper `kobject_del()` and `kobject_put()` sequences,
ensuring correct teardown and preventing memory leaks.

By explicitly calling `kobject_del()` before `kobject_put()`,
the release function is now invoked safely, and internal sysfs
state is correctly cleaned up. This guarantees that the memory
associated with the kobject is fully released and avoids
resource leaks, thereby improving system stability.

Fixes: dce41f5ae253 ("mm/mempolicy: implement the sysfs-based weighted_interleave interface")
Signed-off-by: Rakie Kim <rakie.kim@sk.com>
Signed-off-by: Honggyu Kim <honggyu.kim@sk.com>
Signed-off-by: Yunjeong Mun <yunjeong.mun@sk.com>
Reviewed-by: Gregory Price <gourry@gourry.net>
---
 mm/mempolicy.c | 64 +++++++++++++++++++++++++++-----------------------
 1 file changed, 34 insertions(+), 30 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index XXXXXXX..XXXXXXX 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -XXX,XX +XXX,XX @@ static void sysfs_wi_release(struct kobject *wi_kobj)
 
 	for (i = 0; i < nr_node_ids; i++)
 		sysfs_wi_node_release(node_attrs[i], wi_kobj);
-	kobject_put(wi_kobj);
+
+	kfree(node_attrs);
+	kfree(wi_kobj);
 }
 
 static const struct kobj_type wi_ktype = {
@@ -XXX,XX +XXX,XX @@ static int add_weighted_interleave_group(struct kobject *root_kobj)
 	struct kobject *wi_kobj;
 	int nid, err;
 
-	wi_kobj = kzalloc(sizeof(struct kobject), GFP_KERNEL);
-	if (!wi_kobj)
+	node_attrs = kcalloc(nr_node_ids, sizeof(struct iw_node_attr *),
+			     GFP_KERNEL);
+	if (!node_attrs)
 		return -ENOMEM;
 
+	wi_kobj = kzalloc(sizeof(struct kobject), GFP_KERNEL);
+	if (!wi_kobj) {
+		err = -ENOMEM;
+		goto node_out;
+	}
+
 	err = kobject_init_and_add(wi_kobj, &wi_ktype, root_kobj,
 				   "weighted_interleave");
 	if (err) {
-		kfree(wi_kobj);
-		return err;
+		kobject_put(wi_kobj);
+		goto err_out;
 	}
 
 	for_each_node_state(nid, N_POSSIBLE) {
@@ -XXX,XX +XXX,XX @@ static int add_weighted_interleave_group(struct kobject *root_kobj)
 			break;
 		}
 	}
-	if (err)
+	if (err) {
+		kobject_del(wi_kobj);
 		kobject_put(wi_kobj);
+		goto err_out;
+	}
+
 	return 0;
+
+node_out:
+	kfree(node_attrs);
+err_out:
+	return err;
 }
 
 static void mempolicy_kobj_release(struct kobject *kobj)
@@ -XXX,XX +XXX,XX @@ static void mempolicy_kobj_release(struct kobject *kobj)
 	mutex_unlock(&iw_table_lock);
 	synchronize_rcu();
 	kfree(old);
-	kfree(node_attrs);
 	kfree(kobj);
 }
 
@@ -XXX,XX +XXX,XX @@ static int __init mempolicy_sysfs_init(void)
 	static struct kobject *mempolicy_kobj;
 
 	mempolicy_kobj = kzalloc(sizeof(*mempolicy_kobj), GFP_KERNEL);
-	if (!mempolicy_kobj) {
-		err = -ENOMEM;
-		goto err_out;
-	}
-
-	node_attrs = kcalloc(nr_node_ids, sizeof(struct iw_node_attr *),
-			     GFP_KERNEL);
-	if (!node_attrs) {
-		err = -ENOMEM;
-		goto mempol_out;
-	}
+	if (!mempolicy_kobj)
+		return -ENOMEM;
 
 	err = kobject_init_and_add(mempolicy_kobj, &mempolicy_ktype, mm_kobj,
 				   "mempolicy");
 	if (err)
-		goto node_out;
+		goto err_out;
 
 	err = add_weighted_interleave_group(mempolicy_kobj);
-	if (err) {
-		pr_err("mempolicy sysfs structure failed to initialize\n");
-		kobject_put(mempolicy_kobj);
-		return err;
-	}
+	if (err)
+		goto err_del;
 
-	return err;
-node_out:
-	kfree(node_attrs);
-mempol_out:
-	kfree(mempolicy_kobj);
+	return 0;
+
+err_del:
+	kobject_del(mempolicy_kobj);
 err_out:
-	pr_err("failed to add mempolicy kobject to the system\n");
+	kobject_put(mempolicy_kobj);
 	return err;
 }
 
-- 
2.34.1

Previously, the weighted interleave sysfs structure was statically
managed during initialization. This prevented new nodes from being
recognized when memory hotplug events occurred, limiting the ability
to update or extend sysfs entries dynamically at runtime.

To address this, this patch refactors the sysfs infrastructure and
encapsulates it within a new structure, `sysfs_wi_group`, which holds
both the kobject and an array of node attribute pointers.

By allocating this group structure globally, the per-node sysfs
attributes can be managed beyond initialization time, enabling
external modules to insert or remove node entries in response to
events such as memory hotplug or node online/offline transitions.

Instead of allocating all per-node sysfs attributes at once, the
initialization path now uses the existing sysfs_wi_node_add() and
sysfs_wi_node_delete() helpers. This refactoring makes it possible
to modularly manage per-node sysfs entries and ensures the
infrastructure is ready for runtime extension.

Signed-off-by: Rakie Kim <rakie.kim@sk.com>
Signed-off-by: Honggyu Kim <honggyu.kim@sk.com>
Signed-off-by: Yunjeong Mun <yunjeong.mun@sk.com>
Reviewed-by: Gregory Price <gourry@gourry.net>
---
 mm/mempolicy.c | 73 ++++++++++++++++++++++----------------------------
 1 file changed, 32 insertions(+), 41 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index XXXXXXX..XXXXXXX 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -XXX,XX +XXX,XX @@ struct iw_node_attr {
 	int nid;
 };
 
+struct sysfs_wi_group {
+	struct kobject wi_kobj;
+	struct iw_node_attr *nattrs[];
+};
+
+static struct sysfs_wi_group *wi_group;
+
 static ssize_t node_show(struct kobject *kobj, struct kobj_attribute *attr,
 			 char *buf)
 {
@@ -XXX,XX +XXX,XX @@ static ssize_t node_store(struct kobject *kobj, struct kobj_attribute *attr,
 	return count;
 }
 
-static struct iw_node_attr **node_attrs;
-
-static void sysfs_wi_node_release(struct iw_node_attr *node_attr,
-				  struct kobject *parent)
+static void sysfs_wi_node_delete(int nid)
 {
-	if (!node_attr)
+	if (!wi_group->nattrs[nid])
 		return;
-	sysfs_remove_file(parent, &node_attr->kobj_attr.attr);
-	kfree(node_attr->kobj_attr.attr.name);
-	kfree(node_attr);
+
+	sysfs_remove_file(&wi_group->wi_kobj,
+			  &wi_group->nattrs[nid]->kobj_attr.attr);
+	kfree(wi_group->nattrs[nid]->kobj_attr.attr.name);
+	kfree(wi_group->nattrs[nid]);
 }
 
 static void sysfs_wi_release(struct kobject *wi_kobj)
 {
-	int i;
-
-	for (i = 0; i < nr_node_ids; i++)
-		sysfs_wi_node_release(node_attrs[i], wi_kobj);
+	int nid;
 
-	kfree(node_attrs);
-	kfree(wi_kobj);
+	for (nid = 0; nid < nr_node_ids; nid++)
+		sysfs_wi_node_delete(nid);
+	kfree(wi_group);
 }
 
 static const struct kobj_type wi_ktype = {
@@ -XXX,XX +XXX,XX @@ static const struct kobj_type wi_ktype = {
 	.release = sysfs_wi_release,
 };
 
-static int add_weight_node(int nid, struct kobject *wi_kobj)
+static int sysfs_wi_node_add(int nid)
 {
 	struct iw_node_attr *node_attr;
 	char *name;
@@ -XXX,XX +XXX,XX @@ static int add_weight_node(int nid, struct kobject *wi_kobj)
 	node_attr->kobj_attr.store = node_store;
 	node_attr->nid = nid;
 
-	if (sysfs_create_file(wi_kobj, &node_attr->kobj_attr.attr)) {
+	if (sysfs_create_file(&wi_group->wi_kobj, &node_attr->kobj_attr.attr)) {
 		kfree(node_attr->kobj_attr.attr.name);
 		kfree(node_attr);
 		pr_err("failed to add attribute to weighted_interleave\n");
 		return -ENOMEM;
 	}
 
-	node_attrs[nid] = node_attr;
+	wi_group->nattrs[nid] = node_attr;
 	return 0;
 }
 
-static int add_weighted_interleave_group(struct kobject *root_kobj)
+static int add_weighted_interleave_group(struct kobject *mempolicy_kobj)
 {
-	struct kobject *wi_kobj;
 	int nid, err;
 
-	node_attrs = kcalloc(nr_node_ids, sizeof(struct iw_node_attr *),
-			     GFP_KERNEL);
-	if (!node_attrs)
+	wi_group = kzalloc(struct_size(wi_group, nattrs, nr_node_ids),
+			GFP_KERNEL);
+	if (!wi_group)
 		return -ENOMEM;
 
-	wi_kobj = kzalloc(sizeof(struct kobject), GFP_KERNEL);
-	if (!wi_kobj) {
-		err = -ENOMEM;
-		goto node_out;
-	}
-
-	err = kobject_init_and_add(wi_kobj, &wi_ktype, root_kobj,
+	err = kobject_init_and_add(&wi_group->wi_kobj, &wi_ktype, mempolicy_kobj,
 				   "weighted_interleave");
-	if (err) {
-		kobject_put(wi_kobj);
+	if (err)
 		goto err_out;
-	}
 
 	for_each_node_state(nid, N_POSSIBLE) {
-		err = add_weight_node(nid, wi_kobj);
+		err = sysfs_wi_node_add(nid);
 		if (err) {
 			pr_err("failed to add sysfs [node%d]\n", nid);
-			break;
+			goto err_del;
 		}
 	}
-	if (err) {
-		kobject_del(wi_kobj);
-		kobject_put(wi_kobj);
-		goto err_out;
-	}
 
 	return 0;
 
-node_out:
-	kfree(node_attrs);
+err_del:
+	kobject_del(&wi_group->wi_kobj);
 err_out:
+	kobject_put(&wi_group->wi_kobj);
 	return err;
 }
 
-- 
2.34.1

The weighted interleave policy distributes page allocations across multiple
NUMA nodes based on their performance weight, thereby improving memory
bandwidth utilization. The weight values for each node are configured
through sysfs.

Previously, sysfs entries for configuring weighted interleave were created
for all possible nodes (N_POSSIBLE) at initialization, including nodes that
might not have memory. However, not all nodes in N_POSSIBLE are usable at
runtime, as some may remain memoryless or offline.
This led to sysfs entries being created for unusable nodes, causing
potential misconfiguration issues.

To address this issue, this patch modifies the sysfs creation logic to:
1) Limit sysfs entries to nodes that are online and have memory, avoiding
   the creation of sysfs entries for nodes that cannot be used.
2) Support memory hotplug by dynamically adding and removing sysfs entries
   based on whether a node transitions into or out of the N_MEMORY state.

Additionally, the patch ensures that sysfs attributes are properly managed
when nodes go offline, preventing stale or redundant entries from persisting
in the system.

By making these changes, the weighted interleave policy now manages its
sysfs entries more efficiently, ensuring that only relevant nodes are
considered for interleaving, and dynamically adapting to memory hotplug
events.

Signed-off-by: Rakie Kim <rakie.kim@sk.com>
Signed-off-by: Honggyu Kim <honggyu.kim@sk.com>
Signed-off-by: Yunjeong Mun <yunjeong.mun@sk.com>
---
 mm/mempolicy.c | 109 ++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 86 insertions(+), 23 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index XXXXXXX..XXXXXXX 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -XXX,XX +XXX,XX @@
 #include <asm/tlbflush.h>
 #include <asm/tlb.h>
 #include <linux/uaccess.h>
+#include <linux/memory.h>
 
 #include "internal.h"
 
@@ -XXX,XX +XXX,XX @@ struct iw_node_attr {
 
 struct sysfs_wi_group {
 	struct kobject wi_kobj;
+	struct mutex kobj_lock;
 	struct iw_node_attr *nattrs[];
 };
 
@@ -XXX,XX +XXX,XX @@ static ssize_t node_store(struct kobject *kobj, struct kobj_attribute *attr,
 
 static void sysfs_wi_node_delete(int nid)
 {
-	if (!wi_group->nattrs[nid])
+	struct iw_node_attr *attr;
+
+	if (nid < 0 || nid >= nr_node_ids)
+		return;
+
+	mutex_lock(&wi_group->kobj_lock);
+	attr = wi_group->nattrs[nid];
+	if (!attr) {
+		mutex_unlock(&wi_group->kobj_lock);
 		return;
+	}
+
+	wi_group->nattrs[nid] = NULL;
+	mutex_unlock(&wi_group->kobj_lock);
 
-	sysfs_remove_file(&wi_group->wi_kobj,
-			  &wi_group->nattrs[nid]->kobj_attr.attr);
-	kfree(wi_group->nattrs[nid]->kobj_attr.attr.name);
-	kfree(wi_group->nattrs[nid]);
+	sysfs_remove_file(&wi_group->wi_kobj, &attr->kobj_attr.attr);
+	kfree(attr->kobj_attr.attr.name);
+	kfree(attr);
 }
 
 static void sysfs_wi_release(struct kobject *wi_kobj)
@@ -XXX,XX +XXX,XX @@ static const struct kobj_type wi_ktype = {
 
 static int sysfs_wi_node_add(int nid)
 {
-	struct iw_node_attr *node_attr;
+	int ret = 0;
 	char *name;
+	struct iw_node_attr *new_attr = NULL;
 
-	node_attr = kzalloc(sizeof(*node_attr), GFP_KERNEL);
-	if (!node_attr)
+	if (nid < 0 || nid >= nr_node_ids) {
+		pr_err("Invalid node id: %d\n", nid);
+		return -EINVAL;
+	}
+
+	new_attr = kzalloc(sizeof(struct iw_node_attr), GFP_KERNEL);
+	if (!new_attr)
 		return -ENOMEM;
 
 	name = kasprintf(GFP_KERNEL, "node%d", nid);
 	if (!name) {
-		kfree(node_attr);
+		kfree(new_attr);
 		return -ENOMEM;
 	}
 
-	sysfs_attr_init(&node_attr->kobj_attr.attr);
-	node_attr->kobj_attr.attr.name = name;
-	node_attr->kobj_attr.attr.mode = 0644;
-	node_attr->kobj_attr.show = node_show;
-	node_attr->kobj_attr.store = node_store;
-	node_attr->nid = nid;
+	mutex_lock(&wi_group->kobj_lock);
+	if (wi_group->nattrs[nid]) {
+		mutex_unlock(&wi_group->kobj_lock);
+		pr_info("Node [%d] already exists\n", nid);
+		kfree(new_attr);
+		kfree(name);
+		return 0;
+	}
+	wi_group->nattrs[nid] = new_attr;
 
-	if (sysfs_create_file(&wi_group->wi_kobj, &node_attr->kobj_attr.attr)) {
-		kfree(node_attr->kobj_attr.attr.name);
-		kfree(node_attr);
-		pr_err("failed to add attribute to weighted_interleave\n");
-		return -ENOMEM;
+	sysfs_attr_init(&wi_group->nattrs[nid]->kobj_attr.attr);
+	wi_group->nattrs[nid]->kobj_attr.attr.name = name;
+	wi_group->nattrs[nid]->kobj_attr.attr.mode = 0644;
+	wi_group->nattrs[nid]->kobj_attr.show = node_show;
+	wi_group->nattrs[nid]->kobj_attr.store = node_store;
+	wi_group->nattrs[nid]->nid = nid;
+
+	ret = sysfs_create_file(&wi_group->wi_kobj,
+				&wi_group->nattrs[nid]->kobj_attr.attr);
+	if (ret) {
+		kfree(wi_group->nattrs[nid]->kobj_attr.attr.name);
+		kfree(wi_group->nattrs[nid]);
+		wi_group->nattrs[nid] = NULL;
+		pr_err("Failed to add attribute to weighted_interleave: %d\n", ret);
 	}
+	mutex_unlock(&wi_group->kobj_lock);
 
-	wi_group->nattrs[nid] = node_attr;
-	return 0;
+	return ret;
+}
+
+static int wi_node_notifier(struct notifier_block *nb,
+			       unsigned long action, void *data)
+{
+	int err;
+	struct memory_notify *arg = data;
+	int nid = arg->status_change_nid;
+
+	if (nid < 0)
+		goto notifier_end;
+
+	switch(action) {
+	case MEM_ONLINE:
+		err = sysfs_wi_node_add(nid);
+		if (err) {
+			pr_err("failed to add sysfs [node%d]\n", nid);
+			return NOTIFY_BAD;
+		}
+		break;
+	case MEM_OFFLINE:
+		sysfs_wi_node_delete(nid);
+		break;
+	}
+
+notifier_end:
+	return NOTIFY_OK;
 }
 
 static int add_weighted_interleave_group(struct kobject *mempolicy_kobj)
@@ -XXX,XX +XXX,XX @@ static int add_weighted_interleave_group(struct kobject *mempolicy_kobj)
 			GFP_KERNEL);
 	if (!wi_group)
 		return -ENOMEM;
+	mutex_init(&wi_group->kobj_lock);
 
 	err = kobject_init_and_add(&wi_group->wi_kobj, &wi_ktype, mempolicy_kobj,
 				   "weighted_interleave");
 	if (err)
 		goto err_out;
 
-	for_each_node_state(nid, N_POSSIBLE) {
+	for_each_online_node(nid) {
+		if (!node_state(nid, N_MEMORY))
+			continue;
+
 		err = sysfs_wi_node_add(nid);
 		if (err) {
 			pr_err("failed to add sysfs [node%d]\n", nid);
@@ -XXX,XX +XXX,XX @@ static int add_weighted_interleave_group(struct kobject *mempolicy_kobj)
 		}
 	}
 
+	hotplug_memory_notifier(wi_node_notifier, DEFAULT_CALLBACK_PRI);
 	return 0;
 
 err_del:
-- 
2.34.1

These patches have been tested under CXL-based memory configurations,
including hotplug scenarios, to ensure proper behavior and stability.

mm/mempolicy.c | 193 +++++++++++++++++++++++++++++++------------------
 1 file changed, 124 insertions(+), 69 deletions(-)

base-commit: 0af2f6be1b4281385b618cb86ad946eded089ac8
-- 
2.34.1

Memory leaks occurred when removing sysfs attributes for weighted
interleave. Improper kobject deallocation led to unreleased memory
when initialization failed or when nodes were removed.

This patch resolves the issue by replacing unnecessary `kfree()`
calls with proper `kobject_del()` and `kobject_put()` sequences,
ensuring correct teardown and preventing memory leaks.

Fixes: dce41f5ae253 ("mm/mempolicy: implement the sysfs-based weighted_interleave interface")
Signed-off-by: Rakie Kim <rakie.kim@sk.com>
Signed-off-by: Honggyu Kim <honggyu.kim@sk.com>
Signed-off-by: Yunjeong Mun <yunjeong.mun@sk.com>
Reviewed-by: Gregory Price <gourry@gourry.net>
---
 mm/mempolicy.c | 66 ++++++++++++++++++++++++--------------------------
 1 file changed, 32 insertions(+), 34 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index XXXXXXX..XXXXXXX 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -XXX,XX +XXX,XX @@ static void sysfs_wi_release(struct kobject *wi_kobj)
 
 	for (i = 0; i < nr_node_ids; i++)
 		sysfs_wi_node_release(node_attrs[i], wi_kobj);
-	kobject_put(wi_kobj);
+
+	kfree(node_attrs);
+	kfree(wi_kobj);
 }
 
 static const struct kobj_type wi_ktype = {
@@ -XXX,XX +XXX,XX @@ static int add_weighted_interleave_group(struct kobject *root_kobj)
 	struct kobject *wi_kobj;
 	int nid, err;
 
+	node_attrs = kcalloc(nr_node_ids, sizeof(struct iw_node_attr *),
+			     GFP_KERNEL);
+	if (!node_attrs)
+		return -ENOMEM;
+
 	wi_kobj = kzalloc(sizeof(struct kobject), GFP_KERNEL);
-	if (!wi_kobj)
+	if (!wi_kobj) {
+		kfree(node_attrs);
 		return -ENOMEM;
+	}
 
 	err = kobject_init_and_add(wi_kobj, &wi_ktype, root_kobj,
 				   "weighted_interleave");
-	if (err) {
-		kfree(wi_kobj);
-		return err;
-	}
+	if (err)
+		goto err_put_kobj;
 
 	for_each_node_state(nid, N_POSSIBLE) {
 		err = add_weight_node(nid, wi_kobj);
 		if (err) {
 			pr_err("failed to add sysfs [node%d]\n", nid);
-			break;
+			goto err_del_kobj;
 		}
 	}
-	if (err)
-		kobject_put(wi_kobj);
+
 	return 0;
+
+err_del_kobj:
+	kobject_del(wi_kobj);
+err_put_kobj:
+	kobject_put(wi_kobj);
+	return err;
 }
 
 static void mempolicy_kobj_release(struct kobject *kobj)
@@ -XXX,XX +XXX,XX @@ static void mempolicy_kobj_release(struct kobject *kobj)
 	mutex_unlock(&iw_table_lock);
 	synchronize_rcu();
 	kfree(old);
-	kfree(node_attrs);
 	kfree(kobj);
 }
 
@@ -XXX,XX +XXX,XX @@ static int __init mempolicy_sysfs_init(void)
 	static struct kobject *mempolicy_kobj;
 
 	mempolicy_kobj = kzalloc(sizeof(*mempolicy_kobj), GFP_KERNEL);
-	if (!mempolicy_kobj) {
-		err = -ENOMEM;
-		goto err_out;
-	}
-
-	node_attrs = kcalloc(nr_node_ids, sizeof(struct iw_node_attr *),
-			     GFP_KERNEL);
-	if (!node_attrs) {
-		err = -ENOMEM;
-		goto mempol_out;
-	}
+	if (!mempolicy_kobj)
+		return -ENOMEM;
 
 	err = kobject_init_and_add(mempolicy_kobj, &mempolicy_ktype, mm_kobj,
 				   "mempolicy");
 	if (err)
-		goto node_out;
+		goto err_put_kobj;
 
 	err = add_weighted_interleave_group(mempolicy_kobj);
-	if (err) {
-		pr_err("mempolicy sysfs structure failed to initialize\n");
-		kobject_put(mempolicy_kobj);
-		return err;
-	}
+	if (err)
+		goto err_del_kobj;
 
-	return err;
-node_out:
-	kfree(node_attrs);
-mempol_out:
-	kfree(mempolicy_kobj);
-err_out:
-	pr_err("failed to add mempolicy kobject to the system\n");
+	return 0;
+
+err_del_kobj:
+	kobject_del(mempolicy_kobj);
+err_put_kobj:
+	kobject_put(mempolicy_kobj);
 	return err;
 }
 
-- 
2.34.1

To address this, this patch refactors the sysfs infrastructure and
encapsulates it within a new structure, `sysfs_wi_group`, which holds
both the kobject and an array of node attribute pointers.

Signed-off-by: Rakie Kim <rakie.kim@sk.com>
Signed-off-by: Honggyu Kim <honggyu.kim@sk.com>
Signed-off-by: Yunjeong Mun <yunjeong.mun@sk.com>
Reviewed-by: Gregory Price <gourry@gourry.net>
---
 mm/mempolicy.c | 61 ++++++++++++++++++++++++--------------------------
 1 file changed, 29 insertions(+), 32 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index XXXXXXX..XXXXXXX 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -XXX,XX +XXX,XX @@ struct iw_node_attr {
 	int nid;
 };
 
+struct sysfs_wi_group {
+	struct kobject wi_kobj;
+	struct iw_node_attr *nattrs[];
+};
+
+static struct sysfs_wi_group *wi_group;
+
 static ssize_t node_show(struct kobject *kobj, struct kobj_attribute *attr,
 			 char *buf)
 {
@@ -XXX,XX +XXX,XX @@ static ssize_t node_store(struct kobject *kobj, struct kobj_attribute *attr,
 	return count;
 }
 
-static struct iw_node_attr **node_attrs;
-
-static void sysfs_wi_node_release(struct iw_node_attr *node_attr,
-				  struct kobject *parent)
+static void sysfs_wi_node_delete(int nid)
 {
-	if (!node_attr)
+	if (!wi_group->nattrs[nid])
 		return;
-	sysfs_remove_file(parent, &node_attr->kobj_attr.attr);
-	kfree(node_attr->kobj_attr.attr.name);
-	kfree(node_attr);
+
+	sysfs_remove_file(&wi_group->wi_kobj,
+			  &wi_group->nattrs[nid]->kobj_attr.attr);
+	kfree(wi_group->nattrs[nid]->kobj_attr.attr.name);
+	kfree(wi_group->nattrs[nid]);
 }
 
 static void sysfs_wi_release(struct kobject *wi_kobj)
 {
-	int i;
-
-	for (i = 0; i < nr_node_ids; i++)
-		sysfs_wi_node_release(node_attrs[i], wi_kobj);
+	int nid;
 
-	kfree(node_attrs);
-	kfree(wi_kobj);
+	for (nid = 0; nid < nr_node_ids; nid++)
+		sysfs_wi_node_delete(nid);
+	kfree(wi_group);
 }
 
 static const struct kobj_type wi_ktype = {
@@ -XXX,XX +XXX,XX @@ static const struct kobj_type wi_ktype = {
 	.release = sysfs_wi_release,
 };
 
-static int add_weight_node(int nid, struct kobject *wi_kobj)
+static int sysfs_wi_node_add(int nid)
 {
 	struct iw_node_attr *node_attr;
 	char *name;
@@ -XXX,XX +XXX,XX @@ static int add_weight_node(int nid, struct kobject *wi_kobj)
 	node_attr->kobj_attr.store = node_store;
 	node_attr->nid = nid;
 
-	if (sysfs_create_file(wi_kobj, &node_attr->kobj_attr.attr)) {
+	if (sysfs_create_file(&wi_group->wi_kobj, &node_attr->kobj_attr.attr)) {
 		kfree(node_attr->kobj_attr.attr.name);
 		kfree(node_attr);
 		pr_err("failed to add attribute to weighted_interleave\n");
 		return -ENOMEM;
 	}
 
-	node_attrs[nid] = node_attr;
+	wi_group->nattrs[nid] = node_attr;
 	return 0;
 }
 
-static int add_weighted_interleave_group(struct kobject *root_kobj)
+static int __init add_weighted_interleave_group(struct kobject *mempolicy_kobj)
 {
-	struct kobject *wi_kobj;
 	int nid, err;
 
-	node_attrs = kcalloc(nr_node_ids, sizeof(struct iw_node_attr *),
-			     GFP_KERNEL);
-	if (!node_attrs)
+	wi_group = kzalloc(struct_size(wi_group, nattrs, nr_node_ids),
+			   GFP_KERNEL);
+	if (!wi_group)
 		return -ENOMEM;
 
-	wi_kobj = kzalloc(sizeof(struct kobject), GFP_KERNEL);
-	if (!wi_kobj) {
-		kfree(node_attrs);
-		return -ENOMEM;
-	}
-
-	err = kobject_init_and_add(wi_kobj, &wi_ktype, root_kobj,
+	err = kobject_init_and_add(&wi_group->wi_kobj, &wi_ktype, mempolicy_kobj,
 				   "weighted_interleave");
 	if (err)
 		goto err_put_kobj;
 
 	for_each_node_state(nid, N_POSSIBLE) {
-		err = add_weight_node(nid, wi_kobj);
+		err = sysfs_wi_node_add(nid);
 		if (err) {
 			pr_err("failed to add sysfs [node%d]\n", nid);
 			goto err_del_kobj;
@@ -XXX,XX +XXX,XX @@ static int add_weighted_interleave_group(struct kobject *root_kobj)
 	return 0;
 
 err_del_kobj:
-	kobject_del(wi_kobj);
+	kobject_del(&wi_group->wi_kobj);
 err_put_kobj:
-	kobject_put(wi_kobj);
+	kobject_put(&wi_group->wi_kobj);
 	return err;
 }
 
-- 
2.34.1

Additionally, the patch ensures that sysfs attributes are properly managed
when nodes go offline, preventing stale or redundant entries from persisting
in the system.

Signed-off-by: Rakie Kim <rakie.kim@sk.com>
Signed-off-by: Honggyu Kim <honggyu.kim@sk.com>
Signed-off-by: Yunjeong Mun <yunjeong.mun@sk.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
---
 mm/mempolicy.c | 106 ++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 83 insertions(+), 23 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index XXXXXXX..XXXXXXX 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -XXX,XX +XXX,XX @@
 #include <asm/tlbflush.h>
 #include <asm/tlb.h>
 #include <linux/uaccess.h>
+#include <linux/memory.h>
 
 #include "internal.h"
 
@@ -XXX,XX +XXX,XX @@ struct iw_node_attr {
 
 struct sysfs_wi_group {
 	struct kobject wi_kobj;
+	struct mutex kobj_lock;
 	struct iw_node_attr *nattrs[];
 };
 
@@ -XXX,XX +XXX,XX @@ static ssize_t node_store(struct kobject *kobj, struct kobj_attribute *attr,
 
 static void sysfs_wi_node_delete(int nid)
 {
-	if (!wi_group->nattrs[nid])
+	struct iw_node_attr *attr;
+
+	if (nid < 0 || nid >= nr_node_ids)
+		return;
+
+	mutex_lock(&wi_group->kobj_lock);
+	attr = wi_group->nattrs[nid];
+	if (!attr) {
+		mutex_unlock(&wi_group->kobj_lock);
 		return;
+	}
+
+	wi_group->nattrs[nid] = NULL;
+	mutex_unlock(&wi_group->kobj_lock);
 
-	sysfs_remove_file(&wi_group->wi_kobj,
-			  &wi_group->nattrs[nid]->kobj_attr.attr);
-	kfree(wi_group->nattrs[nid]->kobj_attr.attr.name);
-	kfree(wi_group->nattrs[nid]);
+	sysfs_remove_file(&wi_group->wi_kobj, &attr->kobj_attr.attr);
+	kfree(attr->kobj_attr.attr.name);
+	kfree(attr);
 }
 
 static void sysfs_wi_release(struct kobject *wi_kobj)
@@ -XXX,XX +XXX,XX @@ static const struct kobj_type wi_ktype = {
 
 static int sysfs_wi_node_add(int nid)
 {
-	struct iw_node_attr *node_attr;
+	int ret = 0;
 	char *name;
+	struct iw_node_attr *new_attr = NULL;
 
-	node_attr = kzalloc(sizeof(*node_attr), GFP_KERNEL);
-	if (!node_attr)
+	if (nid < 0 || nid >= nr_node_ids) {
+		pr_err("Invalid node id: %d\n", nid);
+		return -EINVAL;
+	}
+
+	new_attr = kzalloc(sizeof(struct iw_node_attr), GFP_KERNEL);
+	if (!new_attr)
 		return -ENOMEM;
 
 	name = kasprintf(GFP_KERNEL, "node%d", nid);
 	if (!name) {
-		kfree(node_attr);
+		kfree(new_attr);
 		return -ENOMEM;
 	}
 
-	sysfs_attr_init(&node_attr->kobj_attr.attr);
-	node_attr->kobj_attr.attr.name = name;
-	node_attr->kobj_attr.attr.mode = 0644;
-	node_attr->kobj_attr.show = node_show;
-	node_attr->kobj_attr.store = node_store;
-	node_attr->nid = nid;
+	mutex_lock(&wi_group->kobj_lock);
+	if (wi_group->nattrs[nid]) {
+		mutex_unlock(&wi_group->kobj_lock);
+		pr_info("Node [%d] already exists\n", nid);
+		kfree(new_attr);
+		kfree(name);
+		return 0;
+	}
+	wi_group->nattrs[nid] = new_attr;
 
-	if (sysfs_create_file(&wi_group->wi_kobj, &node_attr->kobj_attr.attr)) {
-		kfree(node_attr->kobj_attr.attr.name);
-		kfree(node_attr);
-		pr_err("failed to add attribute to weighted_interleave\n");
-		return -ENOMEM;
+	sysfs_attr_init(&wi_group->nattrs[nid]->kobj_attr.attr);
+	wi_group->nattrs[nid]->kobj_attr.attr.name = name;
+	wi_group->nattrs[nid]->kobj_attr.attr.mode = 0644;
+	wi_group->nattrs[nid]->kobj_attr.show = node_show;
+	wi_group->nattrs[nid]->kobj_attr.store = node_store;
+	wi_group->nattrs[nid]->nid = nid;
+
+	ret = sysfs_create_file(&wi_group->wi_kobj,
+				&wi_group->nattrs[nid]->kobj_attr.attr);
+	if (ret) {
+		kfree(wi_group->nattrs[nid]->kobj_attr.attr.name);
+		kfree(wi_group->nattrs[nid]);
+		wi_group->nattrs[nid] = NULL;
+		pr_err("Failed to add attribute to weighted_interleave: %d\n", ret);
 	}
+	mutex_unlock(&wi_group->kobj_lock);
 
-	wi_group->nattrs[nid] = node_attr;
-	return 0;
+	return ret;
+}
+
+static int wi_node_notifier(struct notifier_block *nb,
+			       unsigned long action, void *data)
+{
+	int err;
+	struct memory_notify *arg = data;
+	int nid = arg->status_change_nid;
+
+	if (nid < 0)
+		return NOTIFY_OK;
+
+	switch(action) {
+	case MEM_ONLINE:
+		err = sysfs_wi_node_add(nid);
+		if (err)
+			pr_err("failed to add sysfs [node%d]\n", nid);
+		break;
+	case MEM_OFFLINE:
+		sysfs_wi_node_delete(nid);
+		break;
+	}
+
+	return NOTIFY_OK;
 }
 
 static int __init add_weighted_interleave_group(struct kobject *mempolicy_kobj)
@@ -XXX,XX +XXX,XX @@ static int __init add_weighted_interleave_group(struct kobject *mempolicy_kobj)
 			   GFP_KERNEL);
 	if (!wi_group)
 		return -ENOMEM;
+	mutex_init(&wi_group->kobj_lock);
 
 	err = kobject_init_and_add(&wi_group->wi_kobj, &wi_ktype, mempolicy_kobj,
 				   "weighted_interleave");
 	if (err)
 		goto err_put_kobj;
 
-	for_each_node_state(nid, N_POSSIBLE) {
+	for_each_online_node(nid) {
+		if (!node_state(nid, N_MEMORY))
+			continue;
+
 		err = sysfs_wi_node_add(nid);
 		if (err) {
 			pr_err("failed to add sysfs [node%d]\n", nid);
@@ -XXX,XX +XXX,XX @@ static int __init add_weighted_interleave_group(struct kobject *mempolicy_kobj)
 		}
 	}
 
+	hotplug_memory_notifier(wi_node_notifier, DEFAULT_CALLBACK_PRI);
 	return 0;
 
 err_del_kobj:
-- 
2.34.1