linux-kernel - Re: sched: CPU #1's llc-sibling CPU #0 is not on the same node!

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Date:	Wed, 27 Feb 2013 09:52:18 +0900
From:	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
To:	Yinghai Lu <yinghai@...nel.org>
CC:	Don Morris <don.morris@...com>, "H. Peter Anvin" <hpa@...or.com>,
	Tejun Heo <tj@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Tony Luck <tony.luck@...el.com>,
	Thomas Renninger <trenn@...e.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Tim Gardner <tim.gardner@...onical.com>,
	<linux-kernel@...r.kernel.org>, <tglx@...utronix.de>,
	<mingo@...hat.com>, <x86@...nel.org>, <a.p.zijlstra@...llo.nl>,
	<jarkko.sakkinen@...el.com>, <tangchen@...fujitsu.com>
Subject: Re: sched: CPU #1's llc-sibling CPU #0 is not on the same node!

2013/02/27 7:44, Yinghai Lu wrote:
> On Tue, Feb 26, 2013 at 1:36 PM, Yinghai Lu <yinghai@...nel.org> wrote:
>> On Mon, Feb 25, 2013 at 2:50 PM, Yinghai Lu <yinghai@...nel.org> wrote:
>>> On Mon, Feb 25, 2013 at 1:27 PM, Don Morris <don.morris@...com> wrote:
>>>> On 02/25/2013 10:32 AM, Tim Gardner wrote:
>>>>> On 02/25/2013 08:02 AM, Tim Gardner wrote:
>>>>>> Is this an expected warning ? I'll boot a vanilla kernel just to be sure.
>>>>>>
>>>>>> rebased against ab7826595e9ec51a51f622c5fc91e2f59440481a in Linus' repo:
>>>>>>
>>>>>
>>>>> Same with a vanilla kernel, so it doesn't appear that any Ubuntu cruft
>>>>> is having an impact:
>>>>
>>>> Reproduced on a HP z620 workstation (E5-2620 instead of E5-2680, but
>>>> still Sandy Bridge, though I don't think that matters).
>>>>
>>>> Bisection leads to:
>>>> # bad: [e8d1955258091e4c92d5a975ebd7fd8a98f5d30f] acpi, memory-hotplug:
>>>> parse SRAT before memblock is ready
>>>>
>>>> Nothing terribly obvious leaps out as to *why* that reshuffling messes
>>>> up the cpu<-->node bindings, but I wanted to put this out there while
>>>> I poke around further. [Note that the SRAT: PXM -> APIC -> Node print
>>>> outs during boot are the same either way -- if you look at the APIC
>>>> numbers of the processors (from /proc/cpuinfo), the processors should
>>>> be assigned to the correct node, but they aren't.] cc'ing Tang Chen
>>>> in case this is obvious to him or he's already fixed it somewhere not
>>>> on Linus's tree yet.
>>>>
>>>> Don Morris
>>>>
>>>>>
>>>>> [    0.170435] ------------[ cut here ]------------
>>>>> [    0.170450] WARNING: at arch/x86/kernel/smpboot.c:324
>>>>> topology_sane.isra.2+0x71/0x84()
>>>>> [    0.170452] Hardware name: S2600CP
>>>>> [    0.170454] sched: CPU #1's llc-sibling CPU #0 is not on the same
>>>>> node! [node: 1 != 0]. Ignoring dependency.
>>>>> [    0.156000] smpboot: Booting Node   1, Processors  #1
>>>>> [    0.170455] Modules linked in:
>>>>> [    0.170460] Pid: 0, comm: swapper/1 Not tainted 3.8.0+ #1
>>>>> [    0.170461] Call Trace:
>>>>> [    0.170466]  [<ffffffff810597bf>] warn_slowpath_common+0x7f/0xc0
>>>>> [    0.170473]  [<ffffffff810598b6>] warn_slowpath_fmt+0x46/0x50
>>>>> [    0.170477]  [<ffffffff816cc752>] topology_sane.isra.2+0x71/0x84
>>>>> [    0.170482]  [<ffffffff816cc9de>] set_cpu_sibling_map+0x23f/0x436
>>>>> [    0.170487]  [<ffffffff816ccd0c>] start_secondary+0x137/0x201
>>>>> [    0.170502] ---[ end trace 09222f596307ca1d ]---
>>>
>>> that commit is totally broken, and it should be reverted.
>>>
>>> 1. numa_init is called several times, NOT just for srat. so those
>>>     nodes_clear(numa_nodes_parsed)
>>>     memset(&numa_meminfo, 0, sizeof(numa_meminfo))
>>> can not be just removed.
>>> please consider sequence is: numaq, srat, amd, dummy.
>>> You need to make fall back path working!
>>>
>>> 2. simply split acpi_numa_init to early_parse_srat.
>>> a. that early_parse_srat is NOT called for ia64, so you break ia64.
>>> b.  for (i = 0; i < MAX_LOCAL_APIC; i++)
>>>       set_apicid_to_node(i, NUMA_NO_NODE)
>>> still left in numa_init. So it will just clear result from early_parse_srat.
>>> it should be moved before that....
>>
>>     c.  it breaks ACPI_TABLE_OVERIDE...as the acpi table scan is moved
>> early before override from INITRD is settled.
>>
>>>
>>> 3. that patch TITLE is total misleading, there is NO x86 in the title,
>>> but it changes
>>> to x86 code.
>>>
>>> 4, it does not CC to TJ and other numa guys...
>
> After looked at the code more, thought that theory that does not let
> kernel use ram
> on hotplug area is not right.
>

> after that commit, following range can not use movable ram:
> 1. real_mode code.... well..funny, legacy cpu0 [0,1M) could be hot-removed?
> 2. dma_continguous ?
> 3. log buff ring.
> 4. initrd... why it will be freed after booting, so it could be on movable...
> 5. crashkernel for kdump...: : looks like we can not put kdump kernel
> above 4G anymore
> 6. initmem_init: it will allocate page table to setup kernel mapping
> for memory..., it should
> be with BRK and near end of max_pfn....

If you use "movablemem_map=srat", abobe memory can not use movable memory.
But in my understanding, current Linux cannot move above memory. So above
memory should not use movable memory.

>
> If node is hotplugable, the mem related stuff like page table and
> vmemmap could be
> on the that node without problem and should be on that node.
>

> assume first cpu only have 1G ram, and other 31 socket will have bunch of ram
> and those cpu with ram could be hotadd and hotremoved.
> Now you want to put page table and vmemmap on first node.
> The system would not boot as not enough memory for cover whole system RAM.

Even if we solve your above mentions, the system cannot boot.
In this case, user should:
   o add ram to first cpu
   o decreases hotpluggable ram by :
     - changing hotpluggable information of SRAT
     - using movablemem_map=nn[KMG]@ss[KMG]

Thansk,
Yasuaki Ishimatsu

>
> e8d1955258091e4c92d5a975ebd7fd8a98f5d30f and related commits should be just
> reverted now.
>
> Thanks
>
> Yinghai
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