linux-kernel - Re: [PATCH v8 02/24] x86/resctrl: kfree() rmid_ptrs from resctrl

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Message-ID: <6ebf108a-49e7-4fc7-a61e-b993ab696c6c@intel.com>
Date: Fri, 15 Dec 2023 20:57:49 -0800
From: Reinette Chatre <reinette.chatre@...el.com>
To: James Morse <james.morse@....com>, <x86@...nel.org>,
	<linux-kernel@...r.kernel.org>
CC: Fenghua Yu <fenghua.yu@...el.com>, Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, H Peter Anvin
	<hpa@...or.com>, Babu Moger <Babu.Moger@....com>,
	<shameerali.kolothum.thodi@...wei.com>, D Scott Phillips OS
	<scott@...amperecomputing.com>, <carl@...amperecomputing.com>,
	<lcherian@...vell.com>, <bobo.shaobowang@...wei.com>,
	<tan.shaopeng@...itsu.com>, <baolin.wang@...ux.alibaba.com>, Jamie Iles
	<quic_jiles@...cinc.com>, Xin Hao <xhao@...ux.alibaba.com>,
	<peternewman@...gle.com>, <dfustini@...libre.com>, <amitsinght@...vell.com>
Subject: Re: [PATCH v8 02/24] x86/resctrl: kfree() rmid_ptrs from
 resctrl_exit()

Hi James,

On 12/15/2023 9:43 AM, James Morse wrote:
> rmid_ptrs[] is allocated from dom_data_init() but never free()d.
> 
> While the exit text ends up in the linker script's DISCARD section,
> the direction of travel is for resctrl to be/have loadable modules.
> 
> Add resctrl_put_mon_l3_config() to cleanup any memory allocated
> by rdt_get_mon_l3_config().
> 
> There is no reason to backport this to a stable kernel.
> 
> Signed-off-by: James Morse <james.morse@....com>
> Tested-by: Babu Moger <babu.moger@....com>
> Reviewed-by: Babu Moger <babu.moger@....com>
> ---
> Changes since v5:
>  * This patch is new
> 
> Changes since v6:
>  * Removed struct rdt_resource argument, added __exit markers to match the
>    only caller.
>  * Adedd a whole stack of functions to maintain symmetry.
> 
> Changes since v7:
>  * Moved the eventual kfree() call to be after rdtgroup_exit()
> ---
>  arch/x86/kernel/cpu/resctrl/core.c     |  6 ++++++
>  arch/x86/kernel/cpu/resctrl/internal.h |  1 +
>  arch/x86/kernel/cpu/resctrl/monitor.c  | 15 +++++++++++++++
>  3 files changed, 22 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
> index 19e0681f0435..b5d4b76f97c5 100644
> --- a/arch/x86/kernel/cpu/resctrl/core.c
> +++ b/arch/x86/kernel/cpu/resctrl/core.c
> @@ -992,8 +992,14 @@ late_initcall(resctrl_late_init);
>  
>  static void __exit resctrl_exit(void)
>  {
> +	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
> +
>  	cpuhp_remove_state(rdt_online);
> +
>  	rdtgroup_exit();
> +
> +	if (r->mon_capable)
> +		rdt_put_mon_l3_config(r);
>  }
>  
>  __exitcall(resctrl_exit);
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index a4f1aa15f0a2..f68c6aecfa66 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -546,6 +546,7 @@ void closid_free(int closid);
>  int alloc_rmid(void);
>  void free_rmid(u32 rmid);
>  int rdt_get_mon_l3_config(struct rdt_resource *r);
> +void __exit rdt_put_mon_l3_config(struct rdt_resource *r);
>  bool __init rdt_cpu_has(int flag);
>  void mon_event_count(void *info);
>  int rdtgroup_mondata_show(struct seq_file *m, void *arg);
> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
> index f136ac046851..5d9864919f1c 100644
> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
> @@ -741,6 +741,16 @@ static int dom_data_init(struct rdt_resource *r)
>  	return 0;
>  }
>  
> +static void __exit dom_data_exit(struct rdt_resource *r)
> +{
> +	mutex_lock(&rdtgroup_mutex);
> +
> +	kfree(rmid_ptrs);
> +	rmid_ptrs = NULL;
> +
> +	mutex_unlock(&rdtgroup_mutex);
> +}
> +
>  static struct mon_evt llc_occupancy_event = {
>  	.name		= "llc_occupancy",
>  	.evtid		= QOS_L3_OCCUP_EVENT_ID,
> @@ -830,6 +840,11 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
>  	return 0;
>  }
>  
> +void __exit rdt_put_mon_l3_config(struct rdt_resource *r)
> +{
> +	dom_data_exit(r);
> +}
> +

I expected the unused resource parameter to be removed because you said ([1]) it would.

>  void __init intel_rdt_mbm_apply_quirk(void)
>  {
>  	int cf_index;

Reinette

[1] https://lore.kernel.org/lkml/c4157536-7e57-0250-dc44-8914f5965ce6@arm.com/