linux-kernel - Re: [PATCH v4 4/5] mm: make processing of movable

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Date:   Tue, 25 Oct 2016 23:15:40 +1100
From:   Balbir Singh <bsingharora@...il.com>
To:     Reza Arbab <arbab@...ux.vnet.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Bharata B Rao <bharata@...ux.vnet.ibm.com>,
        Nathan Fontenot <nfont@...ux.vnet.ibm.com>,
        Stewart Smith <stewart@...ux.vnet.ibm.com>,
        Alistair Popple <apopple@....ibm.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
        Tang Chen <tangchen@...fujitsu.com>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        devicetree@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v4 4/5] mm: make processing of movable_node arch-specific



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@...ux.vnet.ibm.com>
> 
> Acked-by: Balbir Singh <bsingharora@...il.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.