The patch titled
Subject: mm: remove x86-only restriction of movable_node
has been added to the -mm tree. Its filename is
mm-remove-x86-only-restriction-of-movable_node.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-remove-x86-only-restriction-of-movable_node.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-remove-x86-only-restriction-of-movable_node.patch
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From: Reza Arbab <arbab@xxxxxxxxxxxxxxxxxx>
Subject: mm: remove x86-only restriction of movable_node
In commit c5320926e370 ("mem-hotplug: introduce movable_node boot
option"), the memblock allocation direction is changed to bottom-up and
then back to top-down like this:
1. memblock_set_bottom_up(true), called by cmdline_parse_movable_node().
2. memblock_set_bottom_up(false), called by x86's numa_init().
Even though (1) occurs in generic mm code, it is wrapped by #ifdef
CONFIG_MOVABLE_NODE, which depends on X86_64.
This means that when we extend CONFIG_MOVABLE_NODE to non-x86 arches,
things will be unbalanced. (1) will happen for them, but (2) will not.
This toggle was added in the first place because x86 has a delay between
adding memblocks and marking them as hotpluggable. Since other arches do
this marking either immediately or not at all, they do not require the
bottom-up toggle.
So, resolve things by moving (1) from cmdline_parse_movable_node() to
x86's setup_arch(), immediately after the movable_node parameter has
been parsed.
Link: http://lkml.kernel.org/r/1479160961-25840-3-git-send-email-arbab@xxxxxxxxxxxxxxxxxx
Signed-off-by: Reza Arbab <arbab@xxxxxxxxxxxxxxxxxx>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Alistair Popple <apopple@xxxxxxxxxxx>
Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Cc: Balbir Singh <bsingharora@xxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Bharata B Rao <bharata@xxxxxxxxxxxxxxxxxx>
Cc: Frank Rowand <frowand.list@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Nathan Fontenot <nfont@xxxxxxxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Rob Herring <robh+dt@xxxxxxxxxx>
Cc: Stewart Smith <stewart@xxxxxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/kernel-parameters.txt | 2 +-
arch/x86/kernel/setup.c | 24 ++++++++++++++++++++++++
mm/memory_hotplug.c | 20 --------------------
3 files changed, 25 insertions(+), 21 deletions(-)
diff -puN Documentation/kernel-parameters.txt~mm-remove-x86-only-restriction-of-movable_node Documentation/kernel-parameters.txt
--- a/Documentation/kernel-parameters.txt~mm-remove-x86-only-restriction-of-movable_node
+++ a/Documentation/kernel-parameters.txt
@@ -2401,7 +2401,7 @@ bytes respectively. Such letter suffixes
that the amount of memory usable for all allocations
is not too small.
- movable_node [KNL,X86] Boot-time switch to enable the effects
+ movable_node [KNL] Boot-time switch to enable the effects
of CONFIG_MOVABLE_NODE=y. See mm/Kconfig for details.
MTD_Partition= [MTD]
diff -puN arch/x86/kernel/setup.c~mm-remove-x86-only-restriction-of-movable_node arch/x86/kernel/setup.c
--- a/arch/x86/kernel/setup.c~mm-remove-x86-only-restriction-of-movable_node
+++ a/arch/x86/kernel/setup.c
@@ -985,6 +985,30 @@ void __init setup_arch(char **cmdline_p)
parse_early_param();
+#ifdef CONFIG_MEMORY_HOTPLUG
+ /*
+ * Memory used by the kernel cannot be hot-removed because Linux
+ * cannot migrate the kernel pages. When memory hotplug is
+ * enabled, we should prevent memblock from allocating memory
+ * for the kernel.
+ *
+ * ACPI SRAT records all hotpluggable memory ranges. But before
+ * SRAT is parsed, we don't know about it.
+ *
+ * The kernel image is loaded into memory at very early time. We
+ * cannot prevent this anyway. So on NUMA system, we set any
+ * node the kernel resides in as un-hotpluggable.
+ *
+ * Since on modern servers, one node could have double-digit
+ * gigabytes memory, we can assume the memory around the kernel
+ * image is also un-hotpluggable. So before SRAT is parsed, just
+ * allocate memory near the kernel image to try the best to keep
+ * the kernel away from hotpluggable memory.
+ */
+ if (movable_node_is_enabled())
+ memblock_set_bottom_up(true);
+#endif
+
x86_report_nx();
/* after early param, so could get panic from serial */
diff -puN mm/memory_hotplug.c~mm-remove-x86-only-restriction-of-movable_node mm/memory_hotplug.c
--- a/mm/memory_hotplug.c~mm-remove-x86-only-restriction-of-movable_node
+++ a/mm/memory_hotplug.c
@@ -1727,26 +1727,6 @@ static bool can_offline_normal(struct zo
static int __init cmdline_parse_movable_node(char *p)
{
#ifdef CONFIG_MOVABLE_NODE
- /*
- * Memory used by the kernel cannot be hot-removed because Linux
- * cannot migrate the kernel pages. When memory hotplug is
- * enabled, we should prevent memblock from allocating memory
- * for the kernel.
- *
- * ACPI SRAT records all hotpluggable memory ranges. But before
- * SRAT is parsed, we don't know about it.
- *
- * The kernel image is loaded into memory at very early time. We
- * cannot prevent this anyway. So on NUMA system, we set any
- * node the kernel resides in as un-hotpluggable.
- *
- * Since on modern servers, one node could have double-digit
- * gigabytes memory, we can assume the memory around the kernel
- * image is also un-hotpluggable. So before SRAT is parsed, just
- * allocate memory near the kernel image to try the best to keep
- * the kernel away from hotpluggable memory.
- */
- memblock_set_bottom_up(true);
movable_node_enabled = true;
#else
pr_warn("movable_node option not supported\n");
_
Patches currently in -mm which might be from arbab@xxxxxxxxxxxxxxxxxx are
powerpc-mm-allow-memory-hotplug-into-a-memoryless-node.patch
mm-remove-x86-only-restriction-of-movable_node.patch
mm-enable-config_movable_node-on-non-x86-arches.patch
of-fdt-mark-hotpluggable-memory.patch
dt-add-documentation-of-hotpluggable-memory-property.patch
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