Re: resctrl mount fail on v6.13-rc1

["Luck, Tony" <tony.luck@intel.com>]

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

> 
> The subject states "resctrl mount fail" - could you please confirm if
> resctrl cannot be mounted in addition to the lockdep warning?
> 
> Reinette
>