linux-kernel - Re: [PATCH v9 09/15] x86/sgx: Charge mem

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Date: Thu, 15 Feb 2024 15:43:18 -0800
From: Dave Hansen <dave.hansen@...el.com>
To: Haitao Huang <haitao.huang@...ux.intel.com>, jarkko@...nel.org,
 dave.hansen@...ux.intel.com, tj@...nel.org, mkoutny@...e.com,
 linux-kernel@...r.kernel.org, linux-sgx@...r.kernel.org, x86@...nel.org,
 cgroups@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
 hpa@...or.com, sohil.mehta@...el.com, tim.c.chen@...ux.intel.com
Cc: zhiquan1.li@...el.com, kristen@...ux.intel.com, seanjc@...gle.com,
 zhanb@...rosoft.com, anakrish@...rosoft.com, mikko.ylinen@...ux.intel.com,
 yangjie@...rosoft.com, chrisyan@...rosoft.com
Subject: Re: [PATCH v9 09/15] x86/sgx: Charge mem_cgroup for per-cgroup
 reclamation

On 2/5/24 13:06, Haitao Huang wrote:
>  static struct mem_cgroup *sgx_encl_get_mem_cgroup(struct sgx_encl *encl)
>  {
> @@ -1003,14 +1001,6 @@ static struct mem_cgroup *sgx_encl_get_mem_cgroup(struct sgx_encl *encl)
>  	struct sgx_encl_mm *encl_mm;
>  	int idx;
>  
> -	/*
> -	 * If called from normal task context, return the mem_cgroup
> -	 * of the current task's mm. The remainder of the handling is for
> -	 * ksgxd.
> -	 */
> -	if (!current_is_ksgxd())
> -		return get_mem_cgroup_from_mm(current->mm);

Why is this being removed?

Searching the enclave mm list is a last resort.  It's expensive and
imprecise.

get_mem_cgroup_from_mm(current->mm), on the other hand is fast and precise.