Re: resctrl mount fail on v6.13-rc1

[Reinette Chatre <reinette.chatre@intel.com>]

On 12/2/24 6:47 PM, Luck, Tony wrote:
> On Mon, Dec 02, 2024 at 02:26:48PM -0800, Reinette Chatre wrote:
>> Hi Tony,
>>
>> On 12/2/24 1:42 PM, Luck, Tony wrote:
>>> Anyone better a decoding lockdep dumps then me make sense of this?
>>>
>>> All I did was build v6.13-rc1 with (among others)
>>>
>>> CONFIG_PROVE_LOCKING=y
>>> CONFIG_PROVE_RAW_LOCK_NESTING=y
>>> CONFIG_PROVE_RCU=y
>>>
>>> and then mount the resctrl filesystem:
>>>
>>> $ sudo mount -t resctrl resctrl /sys/fs/resctrl
>>>
>>> There are only trivial changes to the resctrl code between
>>> v6.12 (which works) and v6.13-rc1:
>>>
>>> $ git log --oneline v6.13-rc1 ^v6.12 -- arch/x86/kernel/cpu/resctrl
>>> 5a4b3fbb4849 Merge tag 'x86_cache_for_v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
>>> 9bce6e94c4b3 x86/resctrl: Support Sub-NUMA cluster mode SNC6
>>> 29eaa7958367 x86/resctrl: Slightly clean-up mbm_config_show()
>>>
>>> So something in kernfs? Or the way resctrl uses kernfs?
>>
>> I am not seeing this but that may be because I am not testing with
>> selinux enabled. My test kernel has:
>> # CONFIG_SECURITY_SELINUX is not set
>>
>> I am also not running with any btrfs filesystems. 
>>
>> Is this your usual setup in which you are seeing this the first time? Is it
>> perhaps possible for you to bisect?
> 
> Bisection says:
> 
> $ git bisect bad
> f1be1788a32e8fa63416ad4518bbd1a85a825c9d is the first bad commit
> commit f1be1788a32e8fa63416ad4518bbd1a85a825c9d
> Author: Ming Lei <ming.lei@redhat.com>
> Date:   Fri Oct 25 08:37:20 2024 +0800
> 
>     block: model freeze & enter queue as lock for supporting lockdep
> 

Thank you very much Tony. Since you did not respond to the question about
bisect I assumed that you would not do it. I ended up duplicating the bisect
effort after getting an environment in which I can reproduce the issue. Doing so
I am able to confirm the commit pointed to by bisect. 
The commit cannot be reverted cleanly so I could not test v6.13-rc1 with it
reverted.

Ming Lei: I'd be happy to help with testing if you do not have hardware with
which you can reproduce the issue.

Reinette