On 20.12.24 15:45, Gregory Price wrote:
When memory hotplug auto-online is enabled, hotplug memory blocks are
onlined into ZONE_NORMAL by default. The `memhp_default_state` boot
param allows runtime configuration, but no build-time config exists.
Add a build-time configuration option to change default hotplug zone.
build config:
MEMHP_DEFAULT_TYPE
Selections:
MEMHP_DEFAULT_TYPE_NORMAL => mhp_default_online_type = "online"
MEMHP_DEFAULT_TYPE_MOVABLE => mhp_default_online_type = "online_movable"
When MEMORY_HOTPLUG_DEFAULT_ONLINE is disabled, MEMHP_DEFAULT_TYPE is
set to "offline" to match the current system behavior.
ZONE_NORMAL still remains the default, because for systems with a large
amount of hotplug memory, defaulting it to ZONE_MOVABLE may result in
portions failing to online if sufficient ZONE_NORMAL memory does not
exist to describe it.
Signed-off-by: Gregory Price <gourry@xxxxxxxxxx>
---
drivers/base/memory.c | 4 ++--
include/linux/memory_hotplug.h | 5 +++--
mm/Kconfig | 33 +++++++++++++++++++++++++++++++++
mm/memory_hotplug.c | 29 ++++++++++++++++++++++-------
4 files changed, 60 insertions(+), 11 deletions(-)
diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 67858eeb92ed..6f69b01abe51 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[memhp_default_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;
+ memhp_set_default_type(online_type);
return count;
}
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index b27ddce5d324..a43470f0d93c 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 memhp_default_type(void);
+extern void memhp_set_default_type(int online_type);
Please call these "default_online_type". Further keep the "mhp"
terminology, it's more commonly used. We cannot rename the
"memhp_default_state" parameter name unfortunately.
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..b6e63e5306b1 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -565,6 +565,39 @@ config MEMORY_HOTPLUG_DEFAULT_ONLINE
Say N here if you want the default policy to keep all hot-plugged
memory blocks in 'offline' state.
+choice
+ prompt "Memory Hotplug Default Type"
+ depends on MEMORY_HOTPLUG_DEFAULT_ONLINE
+ default MEMHP_DEFAULT_TYPE_NORMAL
+ help
+ Default memory zone for driver managed hotplug memory.
+ Select normal to generally allow kernel usage of this memory.
+ Select movable to generally disallow kernel usage of this memory.
+ Example typical kernel usage would be page structs and page tables.
+
+
+config MEMHP_DEFAULT_TYPE_NORMAL
+ bool "Normal"
+ help
+ Online driver managed hotplug memory into zone normal.
+ Select this if you want the kernel to be able to utilize
+ this memory for kernel data (e.g. page tables).
+
+config MEMHP_DEFAULT_TYPE_MOVABLE
+ bool "Movable"
+ help
+ Online driver managed hotplug memory into zone movable.
+ Select this if you do not want the kernel to be able to
+ utilize this memory for kernel data (e.g. page tables).
+
+endchoice
+
+config MEMHP_DEFAULT_TYPE
+ string
+ default "online" if MEMHP_DEFAULT_TYPE_NORMAL
+ default "online_movable" if MEMHP_DEFAULT_TYPE_MOVABLE
+ default "offline"
+
Could we get rid of CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE and simply have
all three types as choices? normal/movable/offline?
config MEMORY_HOTREMOVE
bool "Allow for memory hot remove"
select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 3b6f93962481..1e4340fa9f07 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -219,11 +219,26 @@ 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 memhp_default_type(void)
+{
+ int type;
+
+ if (mhp_default_online_type >= 0)
+ return mhp_default_online_type;
+
+ type = mhp_online_type_from_str(CONFIG_MEMHP_DEFAULT_TYPE);
+ if (type < 0)
+ type = MMOP_OFFLINE;
How could that ever happen? It's a bit weird that we are parsing strings
when we can just decide that at compile-time using IS_ENABLED() etc?
Apart from that LGTM.
--
Cheers,
David / dhildenb
