linux-kernel - Re: [PATCH v6 02/24] x86/resctrl: kfree() rmid_ptrs from rdtgroup

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Message-ID: <7f95e9c8-73a6-4ccd-97e4-0d3723fbeafb@amd.com>
Date:   Wed, 4 Oct 2023 13:00:29 -0500
From:   "Moger, Babu" <babu.moger@....com>
To:     James Morse <james.morse@....com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Cc:     Fenghua Yu <fenghua.yu@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        H Peter Anvin <hpa@...or.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,
        xingxin.hx@...nanolis.org, 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 v6 02/24] x86/resctrl: kfree() rmid_ptrs from
 rdtgroup_exit()

Hi James,

On 9/14/23 12:21, 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_exit_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>
> ---
> Changes since v5:
>  * This patch is new
> ---
>  arch/x86/kernel/cpu/resctrl/internal.h |  1 +
>  arch/x86/kernel/cpu/resctrl/monitor.c  | 10 ++++++++++
>  arch/x86/kernel/cpu/resctrl/rdtgroup.c |  5 +++++
>  3 files changed, 16 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index 85ceaf9a31ac..57cf1e6a57bd 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -537,6 +537,7 @@ 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 resctrl_exit_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 ded1fc7cb7cb..cfb3f632a4b2 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;
>  }
>  
> +void resctrl_exit_mon_l3_config(struct rdt_resource *r)
> +{
> +	mutex_lock(&rdtgroup_mutex);
> +
> +	kfree(rmid_ptrs);
> +	rmid_ptrs = NULL;
> +
> +	mutex_unlock(&rdtgroup_mutex);
> +}

What is the need for passing "rdt_resource *r" here?
Is mutex_lock required?

Thanks
Babu