linux-kernel - [PATCH v4 2/3] mm/mempolicy: Support dynamic sysfs updates for weighted interleave

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Message-ID: <20250401090901.1050-3-rakie.kim@sk.com>
Date: Tue,  1 Apr 2025 18:08:58 +0900
From: Rakie Kim <rakie.kim@...com>
To: gourry@...rry.net
Cc: akpm@...ux-foundation.org,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	linux-cxl@...r.kernel.org,
	joshua.hahnjy@...il.com,
	dan.j.williams@...el.com,
	ying.huang@...ux.alibaba.com,
	david@...hat.com,
	Jonathan.Cameron@...wei.com,
	kernel_team@...ynix.com,
	honggyu.kim@...com,
	yunjeong.mun@...com,
	rakie.kim@...com
Subject: [PATCH v4 2/3] mm/mempolicy: Support dynamic sysfs updates for weighted interleave

Previously, the weighted interleave sysfs structure was statically
managed, preventing dynamic updates when nodes were added or removed.

This patch restructures the weighted interleave sysfs to support
dynamic insertion and deletion. The sysfs that was part of
the 'weighted_interleave_group' is now globally accessible,
allowing external access to that sysfs.

With this change, sysfs management for weighted interleave is
more flexible, supporting hotplug events and runtime updates
more effectively.

Signed-off-by: Rakie Kim <rakie.kim@...com>
Signed-off-by: Honggyu Kim <honggyu.kim@...com>
Signed-off-by: Yunjeong Mun <yunjeong.mun@...com>
Reviewed-by: Gregory Price <gourry@...rry.net>
---
 mm/mempolicy.c | 71 ++++++++++++++++++++++----------------------------
 1 file changed, 31 insertions(+), 40 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 5950d5d5b85e..3092a792bd28 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -3388,6 +3388,13 @@ 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)
 {
@@ -3430,27 +3437,24 @@ 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_release(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_release(nid);
+	kfree(wi_group);
 }
 
 static const struct kobj_type wi_ktype = {
@@ -3458,7 +3462,7 @@ 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;
@@ -3480,57 +3484,44 @@ 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(sizeof(struct sysfs_wi_group) + 		\
+		       nr_node_ids * sizeof(struct iw_node_attr *),	\
+		       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_out;
 		}
 	}
-	if (err) {
-		kobject_put(wi_kobj);
-		goto err_out;
-	}
 
 	return 0;
 
-node_out:
-	kfree(node_attrs);
 err_out:
+	kobject_put(&wi_group->wi_kobj);
 	return err;
 }
 
-- 
2.34.1