mm/hugetlb: fix WARN_ON(!kobj) in sysfs_create_group()

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.

Link: https://lkml.kernel.org/r/20220816130553.31406-3-linmiaohe@huawei.com
Fixes: 79dfc695525f ("hugetlb: add demote hugetlb page sysfs interfaces")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index e720529..ff991e5 100644 (file)
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3846,6 +3846,7 @@ 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) {