linux-kernel - Re: [Patch v1] ACPI, x86: fix bug in associating hot-added CPUs with corresponding NUMA node

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Date:	Wed, 05 Feb 2014 01:14:54 +0100
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Jiang Liu <jiang.liu@...ux.intel.com>
Cc:	"Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
	Toshi Kani <toshi.kani@...com>,
	Yinghai Lu <yinghai@...nel.org>,
	Yijing Wang <wangyijing@...wei.com>,
	Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	linux-acpi@...r.kernel.org, linux-hotplug@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [Patch v1] ACPI, x86: fix bug in associating hot-added CPUs with corresponding NUMA node

On Monday, January 20, 2014 10:31:54 AM Jiang Liu wrote:
> Current ACPI cpu hotplug driver fails to associate hot-added CPUs with
> corresponding NUMA node when doing socket online. The code path to
> associate CPU with NUMA node is as below:
> acpi_processor_add()
>     ->acpi_processor_get_info()
> 	->acpi_processor_hotadd_init()
> 	    ->acpi_map_lsapic()
> 		->_acpi_map_lsapic()
> 		    ->acpi_map_cpu2node()
> cpu_subsys_online()
>     ->try_online_node()
> 	->node_set_online()
> 
> When doing socket online, a new NUMA node is introduced in addition to
> hot-added CPU and memory device. And the new NUMA node is marked as
> online when onlining hot-added CPUs through sysfs interface
> /sys/devices/system/cpu/cpuxx/online.
> 
> On the other hand, acpi_map_cpu2node() will only build the CPU to node
> map if corresponding NUMA node is already online, so it always fails
> to associate hot-added CPUs with corresponding NUMA node because the
> NUMA node is still in offline state.
> 
> For the fix, we could safely remove the "node_online(node)" check in
> function acpi_map_cpu2node() because it's only called for hot-added CPUs
> by acpi_processor_hotadd_init().
> 
> Signed-off-by: Jiang Liu <jiang.liu@...ux.intel.com>

I wonder what the status here is?  Did this patch go anywhere?

> ---
>  arch/x86/kernel/acpi/boot.c |    8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
> index 6c0b43b..7625de9 100644
> --- a/arch/x86/kernel/acpi/boot.c
> +++ b/arch/x86/kernel/acpi/boot.c
> @@ -614,10 +614,10 @@ static void acpi_map_cpu2node(acpi_handle handle, int cpu, int physid)
>  	int nid;
>  
>  	nid = acpi_get_node(handle);
> -	if (nid == -1 || !node_online(nid))
> -		return;
> -	set_apicid_to_node(physid, nid);
> -	numa_set_node(cpu, nid);
> +	if (nid != -1) {
> +		set_apicid_to_node(physid, nid);
> +		numa_set_node(cpu, nid);
> +	}
>  #endif
>  }
>  
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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