linux-kernel - [PATCH v3 4/5] powerpc/mm: restore top-down allocation when using movable

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Date:   Sun, 25 Sep 2016 13:36:55 -0500
From:   Reza Arbab <arbab@...ux.vnet.ibm.com>
To:     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>,
        Jonathan Corbet <corbet@....net>,
        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>,
        Balbir Singh <bsingharora@...il.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, devicetree@...r.kernel.org,
        linux-mm@...ck.org
Subject: [PATCH v3 4/5] powerpc/mm: restore top-down allocation when using movable_node

At boot, the movable_node option sets bottom-up memblock allocation.

This reduces the chance that, in the window before movable memory has
been identified, an allocation for the kernel might come from a movable
node. By going bottom-up, early allocations will most likely come from
the same node as the kernel image, which is necessarily in a nonmovable
node.

Then, once any known hotplug memory has been marked, allocation can be
reset back to top-down. On x86, this is done in numa_init(). This patch
does the same on power, in numa initmem_init().

Signed-off-by: Reza Arbab <arbab@...ux.vnet.ibm.com>
---
 arch/powerpc/mm/numa.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index d7ac419..fdf1e69 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -945,6 +945,9 @@ void __init initmem_init(void)
 	max_low_pfn = memblock_end_of_DRAM() >> PAGE_SHIFT;
 	max_pfn = max_low_pfn;
 
+	/* bottom-up allocation may have been set by movable_node */
+	memblock_set_bottom_up(false);
+
 	if (parse_numa_properties())
 		setup_nonnuma();
 	else
-- 
1.8.3.1