mm: huge_memory: fix kobject cleanup in thpsize_create error

When kobject_init_and_add() fails, the kobject API requires calling
kobject_put() to properly clean up the memory, not direct kfree().

According to the kobject API documentation, kobject_init_and_add() calls
kobject_init() internally.  If the subsequent kobject_add() fails, the
kobject has still been initialized and must be cleaned up via the
reference count mechanism (kobject_put), not direct kfree().

Direct kfree() leaves the kobject's internal state (including the
reference count and kset membership) uncleaned, which can cause:
 - Memory leaks of kobject internal structures
 - Potential use-after-free if there are pending references
 - Inconsistent state with the rest of the error handling code

This fix matches the pattern used elsewhere in the kernel and in the same
function (err_put label) which correctly uses kobject_put().

Link: https://lore.kernel.org/20260713054154.120915-1-zenghongling@kylinos.cn
Fixes: 3485b88390 ("mm: thp: introduce multi-size THP sysfs interface")
Signed-off-by: Hongling Zeng <zenghongling@kylinos.cn>
Suggested-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Acked-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Hongling Zeng <zenghongling@kylinos.cn>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/huge_memory.c

@@ -818,10 +818,8 @@ static struct thpsize *thpsize_create(int order, struct kobject *parent)
 
 	ret = kobject_init_and_add(&thpsize->kobj, &thpsize_ktype, parent,
 				   "hugepages-%lukB", size);
-	if (ret) {
-		kfree(thpsize);
-		goto err;
-	}
+	if (ret)
+		goto err_put;
 
 
 	ret = sysfs_add_group(&thpsize->kobj, &any_ctrl_attr_grp);