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mm: add build-time option for hotplug memory default online type

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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.

[gourry@gourry.net: update KConfig comments]
  Link: https://lkml.kernel.org/r/20241226182918.648799-1-gourry@gourry.net
Link: https://lkml.kernel.org/r/20241220210709.300066-1-gourry@gourry.net
Signed-off-by: Gregory Price <gourry@gourry.net>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Gregory Price 2024-12-20 16:07:09 -05:00 • committed by Andrew Morton
parent 901083d8f5
commit 44d46b76c3
7 changed files with 89 additions and 23 deletions
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4
Documentation/admin-guide/kernel-parameters.txt
View file

@ -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

4
Documentation/admin-guide/mm/memory-hotplug.rst
View file

@ -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.

5
arch/loongarch/configs/loongson3_defconfig
View file

@ -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

4
drivers/base/memory.c
View file

@ -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;
}

5
include/linux/memory_hotplug.h
View file

@ -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);

57
mm/Kconfig
View file

@ -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"

33
mm/memory_hotplug.c
View file

@ -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;