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

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Message-ID: <1440384.cOMzyfyUzg@vostro.rjw.lan>
Date:	Fri, 07 Feb 2014 13:03:06 +0100
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Jiang Liu <jiang.liu@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.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>, 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 Friday, February 07, 2014 05:17:45 PM Jiang Liu wrote:
> 
> On 2014/2/5 8:14, Rafael J. Wysocki wrote:
> > 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?
> Hi Rafael,
> 	It's still in review stage, hasn't been accepted by any
> maintainer yet.

OK

Peter, are you fine with the patch below?

Rafael


> > 
> >> ---
> >>  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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