[...]
>> +static int thpsize_create(int order, struct kobject *parent)
>> {
>> unsigned long size = (PAGE_SIZE << order) / SZ_1K;
>> + struct thpsize_child *stats;
>> struct thpsize *thpsize;
>> int ret;
>> + /*
>> + * Each child object (currently only "stats" directory) holds a
>> + * reference to the top-level thpsize object, so we can drop our ref to
>> + * the top-level once stats is setup. Then we just need to drop a
>> + * reference on any children to clean everything up. We can't just use
>> + * the attr group name for the stats subdirectory because there may be
>> + * multiple attribute groups to populate inside stats and overlaying
>> + * using the name property isn't supported in that way; each attr group
>> + * name, if provided, must be unique in the parent directory.
>> + */
>> +
>> thpsize = kzalloc(sizeof(*thpsize), GFP_KERNEL);
>> - if (!thpsize)
>> - return ERR_PTR(-ENOMEM);
>> + if (!thpsize) {
>> + ret = -ENOMEM;
>> + goto err;
>> + }
>> + thpsize->order = order;
>> ret = kobject_init_and_add(&thpsize->kobj, &thpsize_ktype, parent,
>> "hugepages-%lukB", size);
>> if (ret) {
>> kfree(thpsize);
>> - return ERR_PTR(ret);
>> + goto err;
>> }
>> - ret = sysfs_create_group(&thpsize->kobj, &thpsize_attr_group);
>> - if (ret) {
>> + stats = kzalloc(sizeof(*stats), GFP_KERNEL);
>> + if (!stats) {
>> kobject_put(&thpsize->kobj);
>> - return ERR_PTR(ret);
>> + ret = -ENOMEM;
>> + goto err;
>> }
>> - ret = sysfs_create_group(&thpsize->kobj, &stats_attr_group);
>> + ret = kobject_init_and_add(&stats->kobj, &thpsize_child_ktype,
>> + &thpsize->kobj, "stats");
>> + kobject_put(&thpsize->kobj);
>> if (ret) {
>> - kobject_put(&thpsize->kobj);
>> - return ERR_PTR(ret);
>> + kfree(stats);
>> + goto err;
>> }
>> - thpsize->order = order;
>> - return thpsize;
>> + if (BIT(order) & THP_ORDERS_ALL_ANON) {
>> + ret = sysfs_create_group(&thpsize->kobj, &thpsize_attr_group);
>> + if (ret)
>> + goto err_put;
>> +
>> + ret = sysfs_create_group(&stats->kobj, &stats_attr_group);
>> + if (ret)
>> + goto err_put;
>> + }
>> +
>> + if (BIT(order) & PAGECACHE_LARGE_ORDERS) {
>> + ret = sysfs_create_group(&stats->kobj, &file_stats_attr_group);
>> + if (ret)
>> + goto err_put;
>> + }
>> +
>> + list_add(&stats->node, &thpsize_child_list);
>> + return 0;
>> +err_put:
>
> IIUC, I think you should call 'sysfs_remove_group' to remove the group before
> putting the kobject.
Are you sure about that? As I understood it, sysfs_create_group() was
conceptually modifying the state of the kobj, so when the kobj gets destroyed,
all its state is tidied up. __kobject_del() (called on the last kobject_put())
calls sysfs_remove_groups() and tidies up the sysfs state as far as I can see?
>
>> + kobject_put(&stats->kobj);
>> +err:
>> + return ret;
>> }
