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Message-ID: <20241226182918.648799-1-gourry@gourry.net>
Date: Thu, 26 Dec 2024 11:29:18 -0700
From: Gregory Price <gourry@...rry.net>
To: linux-mm@...ck.org
Cc: linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org,
loongarch@...ts.linux.dev,
kernel-team@...a.com,
corbet@....net,
david@...hat.com,
akpm@...ux-foundation.org
Subject: [PATCH v4] mm: add build-time option for hotplug memory default online type
v4: updated KConfig comments
Memory hotplug presently auto-onlines memory into a zone the kernel
deems appropriate if CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE=y.
The memhp_default_state boot param enables runtime config, but it's
not possible to do this at build-time.
Remove CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE, and replace it with
CONFIG_MHP_DEFAULT_ONLINE_TYPE_* choices that sync with the boot param.
Selections:
CONFIG_MHP_DEFAULT_ONLINE_TYPE_OFFLINE
=> mhp_default_online_type = "offline"
Memory will not be onlined automatically.
CONFIG_MHP_DEFAULT_ONLINE_TYPE_ONLINE_AUTO
=> mhp_default_online_type = "online"
Memory will be onlined automatically in a zone deemed.
appropriate by the kernel.
CONFIG_MHP_DEFAULT_ONLINE_TYPE_ONLINE_KERNEL
=> mhp_default_online_type = "online_kernel"
Memory will be onlined automatically.
The zone may allow kernel data (e.g. ZONE_NORMAL).
CONFIG_MHP_DEFAULT_ONLINE_TYPE_ONLINE_MOVABLE
=> mhp_default_online_type = "online_movable"
Memory will be onlined automatically.
The zone will be ZONE_MOVABLE.
Default to CONFIG_MHP_DEFAULT_ONLINE_TYPE_OFFLINE to match the
existing default CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE=n behavior.
Existing users of CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE=y should use
CONFIG_MHP_DEFAULT_ONLINE_TYPE_ONLINE_AUTO.
Signed-off-by: Gregory Price <gourry@...rry.net>
Acked-by: David Hildenbrand <david@...hat.com>
---
.../admin-guide/kernel-parameters.txt | 4 +-
.../admin-guide/mm/memory-hotplug.rst | 4 +-
arch/loongarch/configs/loongson3_defconfig | 5 +-
drivers/base/memory.c | 4 +-
include/linux/memory_hotplug.h | 5 +-
mm/Kconfig | 57 ++++++++++++++++---
mm/memory_hotplug.c | 33 ++++++++---
7 files changed, 89 insertions(+), 23 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index c79691eee54f..9138fcd18260 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3351,8 +3351,8 @@
[KNL] Set the initial state for the memory hotplug
onlining policy. If not specified, the default value is
set according to the
- CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE kernel config
- option.
+ CONFIG_MHP_DEFAULT_ONLINE_TYPE kernel config
+ options.
See Documentation/admin-guide/mm/memory-hotplug.rst.
memmap=exactmap [KNL,X86,EARLY] Enable setting of an exact
diff --git a/Documentation/admin-guide/mm/memory-hotplug.rst b/Documentation/admin-guide/mm/memory-hotplug.rst
index cb2c080f400c..33c886f3d198 100644
--- a/Documentation/admin-guide/mm/memory-hotplug.rst
+++ b/Documentation/admin-guide/mm/memory-hotplug.rst
@@ -280,8 +280,8 @@ The following files are currently defined:
blocks; configure auto-onlining.
The default value depends on the
- CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE kernel configuration
- option.
+ CONFIG_MHP_DEFAULT_ONLINE_TYPE kernel configuration
+ options.
See the ``state`` property of memory blocks for details.
``block_size_bytes`` read-only: the size in bytes of a memory block.
diff --git a/arch/loongarch/configs/loongson3_defconfig b/arch/loongarch/configs/loongson3_defconfig
index 4dffc90192f7..1cc6e8843680 100644
--- a/arch/loongarch/configs/loongson3_defconfig
+++ b/arch/loongarch/configs/loongson3_defconfig
@@ -113,7 +113,10 @@ CONFIG_ZBUD=y
CONFIG_ZSMALLOC=m
# CONFIG_COMPAT_BRK is not set
CONFIG_MEMORY_HOTPLUG=y
-CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE=y
+# CONFIG_MHP_DEFAULT_ONLINE_TYPE_OFFLINE is not set
+CONFIG_MHP_DEFAULT_ONLINE_TYPE_ONLINE_AUTO=y
+# CONFIG_MHP_DEFAULT_ONLINE_TYPE_ONLINE_KERNEL is not set
+# CONFIG_MHP_DEFAULT_ONLINE_TYPE_ONLINE_MOVABLE is not set
CONFIG_MEMORY_HOTREMOVE=y
CONFIG_KSM=y
CONFIG_TRANSPARENT_HUGEPAGE=y
diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 67858eeb92ed..348c5dbbfa68 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -512,7 +512,7 @@ static ssize_t auto_online_blocks_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
return sysfs_emit(buf, "%s\n",
- online_type_to_str[mhp_default_online_type]);
+ online_type_to_str[mhp_get_default_online_type()]);
}
static ssize_t auto_online_blocks_store(struct device *dev,
@@ -524,7 +524,7 @@ static ssize_t auto_online_blocks_store(struct device *dev,
if (online_type < 0)
return -EINVAL;
- mhp_default_online_type = online_type;
+ mhp_set_default_online_type(online_type);
return count;
}
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index b27ddce5d324..eaac5ae8c05c 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -144,8 +144,6 @@ extern u64 max_mem_size;
extern int mhp_online_type_from_str(const char *str);
-/* Default online_type (MMOP_*) when new memory blocks are added. */
-extern int mhp_default_online_type;
/* If movable_node boot option specified */
extern bool movable_node_enabled;
static inline bool movable_node_is_enabled(void)
@@ -303,6 +301,9 @@ static inline void __remove_memory(u64 start, u64 size) {}
#endif /* CONFIG_MEMORY_HOTREMOVE */
#ifdef CONFIG_MEMORY_HOTPLUG
+/* Default online_type (MMOP_*) when new memory blocks are added. */
+extern int mhp_get_default_online_type(void);
+extern void mhp_set_default_online_type(int online_type);
extern void __ref free_area_init_core_hotplug(struct pglist_data *pgdat);
extern int __add_memory(int nid, u64 start, u64 size, mhp_t mhp_flags);
extern int add_memory(int nid, u64 start, u64 size, mhp_t mhp_flags);
diff --git a/mm/Kconfig b/mm/Kconfig
index 7949ab121070..1b501db06417 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -550,20 +550,63 @@ menuconfig MEMORY_HOTPLUG
if MEMORY_HOTPLUG
-config MEMORY_HOTPLUG_DEFAULT_ONLINE
- bool "Online the newly added memory blocks by default"
- depends on MEMORY_HOTPLUG
+choice
+ prompt "Memory Hotplug Default Online Type"
+ default MHP_DEFAULT_ONLINE_TYPE_OFFLINE
help
+ Default memory type for hotplugged memory.
+
This option sets the default policy setting for memory hotplug
onlining policy (/sys/devices/system/memory/auto_online_blocks) which
determines what happens to newly added memory regions. Policy setting
can always be changed at runtime.
+
+ The default is 'offline'.
+
+ Select offline to defer onlining to drivers and user policy.
+ Select auto to let the kernel choose what zones to utilize.
+ Select online_kernel to generally allow kernel usage of this memory.
+ Select online_movable to generally disallow kernel usage of this memory.
+
+ Example kernel usage would be page structs and page tables.
+
See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
- Say Y here if you want all hot-plugged memory blocks to appear in
- 'online' state by default.
- Say N here if you want the default policy to keep all hot-plugged
- memory blocks in 'offline' state.
+config MHP_DEFAULT_ONLINE_TYPE_OFFLINE
+ bool "offline"
+ help
+ Hotplugged memory will not be onlined by default.
+ Choose this for systems with drivers and user policy that
+ handle onlining of hotplug memory policy.
+
+config MHP_DEFAULT_ONLINE_TYPE_ONLINE_AUTO
+ bool "auto"
+ help
+ Select this if you want the kernel to automatically online
+ hotplugged memory into the zone it thinks is reasonable.
+ This memory may be utilized for kernel data.
+
+config MHP_DEFAULT_ONLINE_TYPE_ONLINE_KERNEL
+ bool "kernel"
+ help
+ Select this if you want the kernel to automatically online
+ hotplugged memory into a zone capable of being used for kernel
+ data. This typically means ZONE_NORMAL.
+
+config MHP_DEFAULT_ONLINE_TYPE_ONLINE_MOVABLE
+ bool "movable"
+ help
+ Select this if you want the kernel to automatically online
+ hotplug memory into ZONE_MOVABLE. This memory will generally
+ not be utilized for kernel data.
+
+ This should only be used when the admin knows sufficient
+ ZONE_NORMAL memory is available to describe hotplug memory,
+ otherwise hotplug memory may fail to online. For example,
+ sufficient kernel-capable memory (ZONE_NORMAL) must be
+ available to allocate page structs to describe ZONE_MOVABLE.
+
+endchoice
config MEMORY_HOTREMOVE
bool "Allow for memory hot remove"
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 3b6f93962481..e3655f07dd6e 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -219,11 +219,30 @@ void put_online_mems(void)
bool movable_node_enabled = false;
-#ifndef CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE
-int mhp_default_online_type = MMOP_OFFLINE;
-#else
-int mhp_default_online_type = MMOP_ONLINE;
-#endif
+static int mhp_default_online_type = -1;
+int mhp_get_default_online_type(void)
+{
+ if (mhp_default_online_type >= 0)
+ return mhp_default_online_type;
+
+ if (IS_ENABLED(CONFIG_MHP_DEFAULT_ONLINE_TYPE_OFFLINE))
+ mhp_default_online_type = MMOP_OFFLINE;
+ else if (IS_ENABLED(CONFIG_MHP_DEFAULT_ONLINE_TYPE_ONLINE_AUTO))
+ mhp_default_online_type = MMOP_ONLINE;
+ else if (IS_ENABLED(CONFIG_MHP_DEFAULT_ONLINE_TYPE_ONLINE_KERNEL))
+ mhp_default_online_type = MMOP_ONLINE_KERNEL;
+ else if (IS_ENABLED(CONFIG_MHP_DEFAULT_ONLINE_TYPE_ONLINE_MOVABLE))
+ mhp_default_online_type = MMOP_ONLINE_MOVABLE;
+ else
+ mhp_default_online_type = MMOP_OFFLINE;
+
+ return mhp_default_online_type;
+}
+
+void mhp_set_default_online_type(int online_type)
+{
+ mhp_default_online_type = online_type;
+}
static int __init setup_memhp_default_state(char *str)
{
@@ -1328,7 +1347,7 @@ static int check_hotplug_memory_range(u64 start, u64 size)
static int online_memory_block(struct memory_block *mem, void *arg)
{
- mem->online_type = mhp_default_online_type;
+ mem->online_type = mhp_get_default_online_type();
return device_online(&mem->dev);
}
@@ -1575,7 +1594,7 @@ int add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags)
merge_system_ram_resource(res);
/* online pages if requested */
- if (mhp_default_online_type != MMOP_OFFLINE)
+ if (mhp_get_default_online_type() != MMOP_OFFLINE)
walk_memory_blocks(start, size, NULL, online_memory_block);
return ret;
--
2.47.1
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