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From: Reza Arbab <arbab@linux.vnet.ibm.com>
To: Balbir Singh <bsingharora@gmail.com>
Cc: 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>,
	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
Subject: Re: [PATCH v4 4/5] mm: make processing of movable_node arch-specific
Date: Tue, 25 Oct 2016 10:55:07 -0500	[thread overview]
Message-ID: <20161025155507.37kv5akdlgo6m2be@arbab-laptop.austin.ibm.com> (raw)
In-Reply-To: <dcfc8ace-e59e-6b4b-0f2f-4eff9f08f3c1@gmail.com>

On Tue, Oct 25, 2016 at 11:15:40PM +1100, Balbir Singh wrote:
>After the ack, I realized there were some more checks needed, IOW
>questions for you :)

Hey! No takebacks!

The short answer is that neither of these is a concern.

Longer; if you use "movable_node", x86 can identify these nodes at boot. 
They call memblock_mark_hotplug() while parsing the SRAT. Then, when the 
zones are initialized, those markings are used to determine ZONE_MOVABLE.

We have no analog of this SRAT information, so our movable nodes can 
only be created post boot, by hotplugging and explicitly onlining with 
online_movable.

>1. Have you checked to see if our memblock allocations spill
>over to probably hotpluggable nodes?

Since our nodes don't exist at boot, we don't have that short window 
before the zones are drawn where the node has normal memory, and a 
kernel allocation might occur within.

>2. Shouldn't we be marking nodes discovered as movable via
>memblock_mark_hotplug()?

Again, this early boot marking mechanism only applies to movable_node.

-- 
Reza Arbab

  reply	other threads:[~2016-10-25 15:55 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-10-06 18:36 [PATCH v4 0/5] powerpc/mm: movable hotplug memory nodes Reza Arbab
2016-10-06 18:36 ` [PATCH v4 1/5] drivers/of: introduce of_fdt_device_is_available() Reza Arbab
2016-10-06 18:36 ` [PATCH v4 2/5] drivers/of: do not add memory for unavailable nodes Reza Arbab
2016-10-11 13:58   ` Rob Herring
2016-10-21  6:22   ` Alistair Popple
2016-10-23  1:51     ` Reza Arbab
2016-10-24 10:24     ` Michael Ellerman
2016-10-24 18:20       ` Reza Arbab
2016-10-06 18:36 ` [PATCH v4 3/5] powerpc/mm: allow memory hotplug into a memoryless node Reza Arbab
2016-10-20  3:30   ` Balbir Singh
2016-10-20 14:38     ` Reza Arbab
2016-10-25  9:39     ` Michael Ellerman
2016-10-06 18:36 ` [PATCH v4 4/5] mm: make processing of movable_node arch-specific Reza Arbab
2016-10-07  6:37   ` Aneesh Kumar K.V
2016-10-11 12:26   ` Balbir Singh
2016-10-25 12:15     ` Balbir Singh
2016-10-25 15:55       ` Reza Arbab [this message]
2016-10-25 22:34         ` Balbir Singh
2016-10-26  0:49           ` Reza Arbab
2016-10-26 10:52             ` Michael Ellerman
2016-10-26 17:03               ` Reza Arbab
2016-10-25 22:59         ` Balbir Singh
2016-10-06 18:36 ` [PATCH v4 5/5] mm: enable CONFIG_MOVABLE_NODE on non-x86 arches Reza Arbab
2016-10-07  6:40   ` Aneesh Kumar K.V
2016-10-11 13:17   ` Balbir Singh

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