Re: blktests failures with v6.11-rc1 kernel

[Nilay Shroff <nilay@linux.ibm.com>]

On 8/2/24 18:04, Shinichiro Kawasaki wrote:
> CC+: Yi Zhang,
> 
> On Aug 02, 2024 / 17:46, Nilay Shroff wrote:
>>
>>
>> On 8/2/24 14:39, Shinichiro Kawasaki wrote:
>>>
>>> #3: nvme/052 (CKI failure)
>>>
>>>    The CKI project reported that nvme/052 fails occasionally [4].
>>>    This needs further debug effort.
>>>
>>>   nvme/052 (tr=loop) (Test file-ns creation/deletion under one subsystem) [failed]
>>>       runtime    ...  22.209s
>>>       --- tests/nvme/052.out	2024-07-30 18:38:29.041716566 -0400
>>>       +++ /mnt/tests/gitlab.com/redhat/centos-stream/tests/kernel/kernel-tests/-/archive/production/kernel-tests-production.zip/storage/blktests/nvme/nvme-loop/blktests/results/nodev_tr_loop/nvme/052.out.bad	2024-07-30 18:45:35.438067452 -0400
>>>       @@ -1,2 +1,4 @@
>>>        Running nvme/052
>>>       +cat: /sys/block/nvme1n2/uuid: No such file or directory
>>>       +cat: /sys/block/nvme1n2/uuid: No such file or directory
>>>        Test complete
>>>
>>>    [4] https://datawarehouse.cki-project.org/kcidb/tests/13669275
>>
>> I just checked the console logs of the nvme/052 and from the logs it's 
>> apparent that all namespaces were created successfully and so it's strange
>> to see that the test couldn't access "/sys/block/nvme1n2/uuid".
> 
> I agree that it's strange. I think the "No such file or directory" error
> happened in _find_nvme_ns(), and it checks existence of the uuid file before
> the cat command. I have no idea why the error happens.
> 
Yes exactly, and these two operations (checking the existence of uuid
and cat command) are not atomic. So the only plausible theory I have at this 
time is "if namespace is deleted after checking the existence of uuid but 
before cat command is executed" then this issue may potentially manifests. 
Furthermore, as you mentioned, this issue is seen on the test machine 
occasionally, so I asked if there's a possibility of simultaneous blktest 
or some other tests running on this system.

Thanks,
--Nilay