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Subject: Re: [PATCH v10 12/14] x86/sgx: Turn on per-cgroup EPC reclamation
References: <20240328002229.30264-1-haitao.huang@linux.intel.com>
 <20240328002229.30264-13-haitao.huang@linux.intel.com>
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Date: Mon, 08 Apr 2024 23:23:21 -0500
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From: "Haitao Huang" <haitao.huang@linux.intel.com>
Organization: Intel
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On Mon, 08 Apr 2024 17:37:10 -0500, Huang, Kai <kai.huang@intel.com> wrote:

>
>
> On 9/04/2024 6:03 am, Haitao Huang wrote:
>>>>
>>  The misc root cgroup is a static similar to sgx_cg_root. So  
>> misc_cg_root()  won't be NULL
>> However, based on how css_misc() was check NULL, I suppose  
>> sgx_get_current_cg() may be NULL when cgroup is disabled (again not  
>> 100% sure but we handle it anyway)
>
> Could you help to check?  Sorry I am busy on something else thus won't  
> be able to do any actual check.
>
It's always non-NULL based on testing.

It's hard for me to say definitely by reading the code. But IIUC  
cgroup_disable command-line only blocks operations in /sys/fs/cgroup so  
user space can't set up controllers and config limits, etc., for the  
diasabled ones. Each task->cgroups would still have a non-NULL pointer to  
the static root object for each cgroup that is enabled by KConfig, so  
get_current_misc_cg() thus  sgx_get_current_cg() should not return NULL  
regardless 'cgroup_disable=misc'.

Maybe @Michal or @tj can confirm?

Thanks
Haitao