Qu Wenruo writes:
>On 2020/7/15 下午9:49, Chris Down wrote:
>> While testing my pending patches on top of linux-next, I encountered a
>> bug that seems related to this patch during btrfs unmount. Specifically,
>> a null pointer dereference in kobject_del inside btrfs_sysfs_del_qgroups
>> from close_ctree.
>>
>> The fix may be as simple as checking if the kobject is initialised,
>> although perhaps it should always be initialised in this case, so I'll
>> leave you to work out what the real issue is :-)
>
>Thank you very much for the report.
>
>May I ask if the qgroup is enabled? Or qgroup is not enabled at all?

I have quotas disabled, so I assume qgroup is also implicitly disabled.