Re: [PATCH v5 16/18] x86/sgx: Limit process EPC usage with misc cgroup controller

[Huang, Kai]

> +static inline struct sgx_epc_lru_lists *epc_cg_lru(struct sgx_epc_cgroup *epc_cg)
> +{
> +	if (epc_cg)
> +		return &epc_cg->lru;
> +	return NULL;
> +}
> 

It's legal to return NULL EPC cgroup for a given EPC page, i.e., when the
enclave isn't assigned to any cgroup.  But ...

>  
>  static inline struct sgx_epc_lru_lists *sgx_lru_lists(struct sgx_epc_page *epc_page)
>  {
> +	if (IS_ENABLED(CONFIG_CGROUP_SGX_EPC))
> +		return epc_cg_lru(epc_page->epc_cg);
> +
>  	return &sgx_global_lru;
>  }

... here is it legal to return a NULL LRU list?

It appears you always want to return a valid LRU list.  That is, if EPC cgroup
is enabled, and when the EPC page doesn't belong to any cgroup, then you want to
return the sgx_global_lru ?