[PATCH 2/4] mm/mempolicy: Enable sysfs support for memory hotplug in weighted interleave

[Rakie Kim <rakie.kim@sk.com>]

Previously, sysfs entries for weighted interleave were only created during
initialization, preventing dynamically added memory nodes from being recognized.

This patch enables sysfs registration for nodes added via memory hotplug,
allowing weighted interleave settings to be updated as the system memory
configuration changes.

Signed-off-by: Rakie Kim <rakie.kim@sk.com>
---
 mm/mempolicy.c | 51 +++++++++++++++++++++++++++++++-------------------
 1 file changed, 32 insertions(+), 19 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 385607179ebd..fc10a9a4be86 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -3389,6 +3389,13 @@ struct iw_node_attr {
 	int nid;
 };
 
+struct iw_node_group {
+	struct kobject *wi_kobj;
+	struct iw_node_attr **nattrs;
+};
+
+static struct iw_node_group *ngrp;
+
 static ssize_t node_show(struct kobject *kobj, struct kobj_attribute *attr,
 			 char *buf)
 {
@@ -3431,8 +3438,6 @@ 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)
 {
@@ -3448,7 +3453,7 @@ 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);
+		sysfs_wi_node_release(ngrp->nattrs[i], wi_kobj);
 	kobject_put(wi_kobj);
 }
 
@@ -3486,12 +3491,10 @@ static int add_weight_node(int nid, struct kobject *wi_kobj)
 		return -ENOMEM;
 	}
 
-	node_attrs[nid] = node_attr;
+	ngrp->nattrs[nid] = node_attr;
 	return 0;
 }
 
-struct kobject *wi_kobj;
-
 static int wi_node_notifier(struct notifier_block *nb,
 			       unsigned long action, void *data)
 {
@@ -3504,10 +3507,10 @@ static int wi_node_notifier(struct notifier_block *nb,
 
 	switch(action) {
 	case MEM_ONLINE:
-		err = add_weight_node(nid, wi_kobj);
+		err = add_weight_node(nid, ngrp->wi_kobj);
 		if (err) {
 			pr_err("failed to add sysfs [node%d]\n", nid);
-			kobject_put(wi_kobj);
+			kobject_put(ngrp->wi_kobj);
 			return NOTIFY_BAD;
 		}
 		break;
@@ -3521,14 +3524,14 @@ static int add_weighted_interleave_group(struct kobject *root_kobj)
 {
 	int nid, err;
 
-	wi_kobj = kzalloc(sizeof(struct kobject), GFP_KERNEL);
-	if (!wi_kobj)
+	ngrp->wi_kobj = kzalloc(sizeof(struct kobject), GFP_KERNEL);
+	if (!ngrp->wi_kobj)
 		return -ENOMEM;
 
-	err = kobject_init_and_add(wi_kobj, &wi_ktype, root_kobj,
+	err = kobject_init_and_add(ngrp->wi_kobj, &wi_ktype, root_kobj,
 				   "weighted_interleave");
 	if (err) {
-		kfree(wi_kobj);
+		kfree(ngrp->wi_kobj);
 		return err;
 	}
 
@@ -3536,7 +3539,7 @@ static int add_weighted_interleave_group(struct kobject *root_kobj)
 		if (!node_state(nid, N_MEMORY))
 			continue;
 
-		err = add_weight_node(nid, wi_kobj);
+		err = add_weight_node(nid, ngrp->wi_kobj);
 		if (err) {
 			pr_err("failed to add sysfs [node%d]\n", nid);
 			goto err_out;
@@ -3547,7 +3550,7 @@ static int add_weighted_interleave_group(struct kobject *root_kobj)
 	return 0;
 
 err_out:
-	kobject_put(wi_kobj);
+	kobject_put(ngrp->wi_kobj);
 	return err;
 }
 
@@ -3562,7 +3565,9 @@ static void mempolicy_kobj_release(struct kobject *kobj)
 	mutex_unlock(&iw_table_lock);
 	synchronize_rcu();
 	kfree(old);
-	kfree(node_attrs);
+
+	kfree(ngrp->nattrs);
+	kfree(ngrp);
 	kfree(kobj);
 }
 
@@ -3581,13 +3586,19 @@ static int __init mempolicy_sysfs_init(void)
 		goto err_out;
 	}
 
-	node_attrs = kcalloc(nr_node_ids, sizeof(struct iw_node_attr *),
-			     GFP_KERNEL);
-	if (!node_attrs) {
+	ngrp = kzalloc(sizeof(*ngrp), GFP_KERNEL);
+	if (!ngrp) {
 		err = -ENOMEM;
 		goto mempol_out;
 	}
 
+	ngrp->nattrs = kcalloc(nr_node_ids, sizeof(struct iw_node_attr *),
+			     GFP_KERNEL);
+	if (!ngrp->nattrs) {
+		err = -ENOMEM;
+		goto ngrp_out;
+	}
+
 	err = kobject_init_and_add(mempolicy_kobj, &mempolicy_ktype, mm_kobj,
 				   "mempolicy");
 	if (err)
@@ -3602,7 +3613,9 @@ static int __init mempolicy_sysfs_init(void)
 
 	return err;
 node_out:
-	kfree(node_attrs);
+	kfree(ngrp->nattrs);
+ngrp_out:
+	kfree(ngrp);
 mempol_out:
 	kfree(mempolicy_kobj);
 err_out:
-- 
2.34.1