linux-kernel - [PATCH 5/6] mm/hugetlb: fix sysfs group leak in hugetlb_unregister

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Date:   Tue, 16 Aug 2022 21:05:52 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <akpm@...ux-foundation.org>, <mike.kravetz@...cle.com>,
        <songmuchun@...edance.com>
CC:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        <linmiaohe@...wei.com>
Subject: [PATCH 5/6] mm/hugetlb: fix sysfs group leak in hugetlb_unregister_node()

The sysfs group per_node_hstate_attr_group and hstate_demote_attr_group
when h->demote_order != 0 are created in hugetlb_register_node(). But
these sysfs groups are not removed when unregister the node, thus sysfs
group is leaked. Using sysfs_remove_group() to fix this issue.

Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
---
 mm/hugetlb.c | 25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index b69d7808f457..e1356ad57087 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3850,12 +3850,18 @@ static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
 	}
 
 	if (h->demote_order) {
-		if (sysfs_create_group(hstate_kobjs[hi],
-					&hstate_demote_attr_group))
+		retval = sysfs_create_group(hstate_kobjs[hi],
+					    &hstate_demote_attr_group);
+		if (retval) {
 			pr_warn("HugeTLB unable to create demote interfaces for %s\n", h->name);
+			sysfs_remove_group(hstate_kobjs[hi], hstate_attr_group);
+			kobject_put(hstate_kobjs[hi]);
+			hstate_kobjs[hi] = NULL;
+			return retval;
+		}
 	}
 
-	return retval;
+	return 0;
 }
 
 static void __init hugetlb_sysfs_init(void)
@@ -3941,10 +3947,15 @@ static void hugetlb_unregister_node(struct node *node)
 
 	for_each_hstate(h) {
 		int idx = hstate_index(h);
-		if (nhs->hstate_kobjs[idx]) {
-			kobject_put(nhs->hstate_kobjs[idx]);
-			nhs->hstate_kobjs[idx] = NULL;
-		}
+		struct kobject *hstate_kobj = nhs->hstate_kobjs[idx];
+
+		if (!hstate_kobj)
+			continue;
+		if (h->demote_order)
+			sysfs_remove_group(hstate_kobj, &hstate_demote_attr_group);
+		sysfs_remove_group(hstate_kobj, &per_node_hstate_attr_group);
+		kobject_put(hstate_kobj);
+		nhs->hstate_kobjs[idx] = NULL;
 	}
 
 	kobject_put(nhs->hugepages_kobj);
-- 
2.23.0