[PATCH v2 2/6] mm/hugetlb: fix WARN_ON(!kobj) in sysfs_create_group()

[Miaohe Lin]

If sysfs_create_group() fails with hstate_attr_group, hstate_kobjs[hi]
will be set to NULL. Then it will be passed to sysfs_create_group() if
h->demote_order != 0 thus triggering WARN_ON(!kobj) check. Fix this by
making sure hstate_kobjs[hi] != NULL when calling sysfs_create_group.

Fixes: 79dfc695525f ("hugetlb: add demote hugetlb page sysfs interfaces")
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
---
 mm/hugetlb.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 19a7a83af569..d46dfe5ba62c 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3847,6 +3847,7 @@ static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
 	if (retval) {
 		kobject_put(hstate_kobjs[hi]);
 		hstate_kobjs[hi] = NULL;
+		return retval;
 	}
 
 	if (h->demote_order) {
-- 
2.23.0