Subject: Re: [PATCH v4 4/5] mm: make processing of movable_node arch-specific
To: Reza Arbab <arbab@linux.vnet.ibm.com>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>, Rob Herring <robh+dt@kernel.org>,
        Frank Rowand <frowand.list@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>
References: <1475778995-1420-1-git-send-email-arbab@linux.vnet.ibm.com>
 <1475778995-1420-5-git-send-email-arbab@linux.vnet.ibm.com>
 <235f2d20-cf84-08df-1fb4-08ee258fdc52@gmail.com>
Cc: Bharata B Rao <bharata@linux.vnet.ibm.com>,
        Nathan Fontenot <nfont@linux.vnet.ibm.com>,
        Stewart Smith <stewart@linux.vnet.ibm.com>,
        Alistair Popple <apopple@au1.ibm.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
        Tang Chen <tangchen@cn.fujitsu.com>, linux-kernel@vger.kernel.org,
        linuxppc-dev@lists.ozlabs.org, devicetree@vger.kernel.org,
        linux-mm@kvack.org
From: Balbir Singh <bsingharora@gmail.com>
Message-ID: <dcfc8ace-e59e-6b4b-0f2f-4eff9f08f3c1@gmail.com>
Date: Tue, 25 Oct 2016 23:15:40 +1100
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On 11/10/16 23:26, Balbir Singh wrote:
> 
> 
> On 07/10/16 05:36, Reza Arbab wrote:
>> Currently, CONFIG_MOVABLE_NODE depends on X86_64. In preparation to
>> enable it for other arches, we need to factor a detail which is unique
>> to x86 out of the generic mm code.
>>
>> Specifically, as documented in kernel-parameters.txt, the use of
>> "movable_node" should remain restricted to x86:
>>
>> movable_node    [KNL,X86] Boot-time switch to enable the effects
>>                 of CONFIG_MOVABLE_NODE=y. See mm/Kconfig for details.
>>
>> This option tells x86 to find movable nodes identified by the ACPI SRAT.
>> On other arches, it would have no benefit, only the undesired side
>> effect of setting bottom-up memblock allocation.
>>
>> Since #ifdef CONFIG_MOVABLE_NODE will no longer be enough to restrict
>> this option to x86, move it to an arch-specific compilation unit
>> instead.
>>
>> Signed-off-by: Reza Arbab <arbab@linux.vnet.ibm.com>
> 
> Acked-by: Balbir Singh <bsingharora@gmail.com>
> 

After the ack, I realized there were some more checks needed, IOW
questions for you :)

1. Have you checked to see if our memblock allocations spill
over to probably hotpluggable nodes?
2. Shouldn't we be marking nodes discovered as movable via
memblock_mark_hotplug()?

Balbir Singh.