linux-kernel - Re: [PATCH v9 12/15] x86/sgx: Expose sgx_epc_cgroup_reclaim

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Date: Wed, 21 Feb 2024 11:10:36 +0000
From: "Huang, Kai" <kai.huang@...el.com>
To: "hpa@...or.com" <hpa@...or.com>, "tim.c.chen@...ux.intel.com"
	<tim.c.chen@...ux.intel.com>, "linux-sgx@...r.kernel.org"
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	"tglx@...utronix.de" <tglx@...utronix.de>, "haitao.huang@...ux.intel.com"
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CC: "mikko.ylinen@...ux.intel.com" <mikko.ylinen@...ux.intel.com>,
	"seanjc@...gle.com" <seanjc@...gle.com>, "anakrish@...rosoft.com"
	<anakrish@...rosoft.com>, "Zhang, Bo" <zhanb@...rosoft.com>,
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	<yangjie@...rosoft.com>, "Li, Zhiquan1" <zhiquan1.li@...el.com>,
	"chrisyan@...rosoft.com" <chrisyan@...rosoft.com>
Subject: Re: [PATCH v9 12/15] x86/sgx: Expose sgx_epc_cgroup_reclaim_pages()
 for global reclaimer

On Mon, 2024-02-05 at 13:06 -0800, Haitao Huang wrote:
> From: Kristen Carlson Accardi <kristen@...ux.intel.com>
> 
> When cgroup is enabled, all reclaimable pages will be tracked in cgroup
> LRUs. The global reclaimer needs to start reclamation from the root
> cgroup. Expose the top level cgroup reclamation function so the global
> reclaimer can reuse it.
> 
> Co-developed-by: Sean Christopherson <sean.j.christopherson@...el.com>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> Signed-off-by: Kristen Carlson Accardi <kristen@...ux.intel.com>
> Co-developed-by: Haitao Huang <haitao.huang@...ux.intel.com>
> Signed-off-by: Haitao Huang <haitao.huang@...ux.intel.com>
> ---
> V8:
> - Remove unneeded breaks in function declarations. (Jarkko)
> 
> V7:
> - Split this out from the big patch, #10 in V6. (Dave, Kai)
> ---
>  arch/x86/kernel/cpu/sgx/epc_cgroup.c | 2 +-
>  arch/x86/kernel/cpu/sgx/epc_cgroup.h | 7 +++++++
>  2 files changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/cpu/sgx/epc_cgroup.c b/arch/x86/kernel/cpu/sgx/epc_cgroup.c
> index abf74fdb12b4..6e31f8727b8a 100644
> --- a/arch/x86/kernel/cpu/sgx/epc_cgroup.c
> +++ b/arch/x86/kernel/cpu/sgx/epc_cgroup.c
> @@ -96,7 +96,7 @@ bool sgx_epc_cgroup_lru_empty(struct misc_cg *root)
>   * @indirect:   In ksgxd or EPC cgroup work queue context.
>   * Return:	Number of pages reclaimed.
>   */
> -static unsigned int sgx_epc_cgroup_reclaim_pages(struct misc_cg *root, bool indirect)
> +unsigned int sgx_epc_cgroup_reclaim_pages(struct misc_cg *root, bool indirect)
>  {
>  	/*
>  	 * Attempting to reclaim only a few pages will often fail and is
> diff --git a/arch/x86/kernel/cpu/sgx/epc_cgroup.h b/arch/x86/kernel/cpu/sgx/epc_cgroup.h
> index d061cd807b45..5b3e8e1b8630 100644
> --- a/arch/x86/kernel/cpu/sgx/epc_cgroup.h
> +++ b/arch/x86/kernel/cpu/sgx/epc_cgroup.h
> @@ -31,6 +31,11 @@ static inline int sgx_epc_cgroup_try_charge(struct sgx_epc_cgroup *epc_cg, bool
>  static inline void sgx_epc_cgroup_uncharge(struct sgx_epc_cgroup *epc_cg) { }
>  
>  static inline void sgx_epc_cgroup_init(void) { }
> +
> +static inline unsigned int sgx_epc_cgroup_reclaim_pages(struct misc_cg *root, bool indirect)
> +{
> +	return 0;
> +}
>  #else
>  struct sgx_epc_cgroup {
>  	struct misc_cg *cg;
> @@ -69,6 +74,8 @@ static inline void sgx_put_epc_cg(struct sgx_epc_cgroup *epc_cg)
>  int sgx_epc_cgroup_try_charge(struct sgx_epc_cgroup *epc_cg, bool reclaim);
>  void sgx_epc_cgroup_uncharge(struct sgx_epc_cgroup *epc_cg);
>  bool sgx_epc_cgroup_lru_empty(struct misc_cg *root);
> +unsigned int sgx_epc_cgroup_reclaim_pages(struct misc_cg *root, bool indirect);
> +
>  void sgx_epc_cgroup_init(void);
>  
>  #endif

I'd just prefer to merge patch such like this to the one that actually uses the
exposed function.  It's just couple of LOC and we don't deserve to read these
repeated changelog and move back and forth between patches during review.