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/* SPDX-License-Identifier: GPL-2.0 */
* include/linux/memory.h - generic memory definition
* This is mainly for topological representation. We define the
* basic "struct memory_block" here, which can be embedded in per-arch
* definitions or NUMA information.
* Basic handling of the devices is done in drivers/base/memory.c
* and system devices are handled in drivers/base/sys.c.
* Memory block are exported via sysfs in the class/memory/devices/
* directory.
#ifndef _LINUX_MEMORY_H_
#define _LINUX_MEMORY_H_
#include <linux/node.h>
#include <linux/compiler.h>
#include <linux/mutex.h>
#include <linux/notifier.h>
* struct memory_group - a logical group of memory blocks
* @nid: The node id for all memory blocks inside the memory group.
* @blocks: List of all memory blocks belonging to this memory group.
* @present_kernel_pages: Present (online) memory outside ZONE_MOVABLE of this
* memory group.
* @present_movable_pages: Present (online) memory in ZONE_MOVABLE of this
* memory group.
* @is_dynamic: The memory group type: static vs. dynamic
* @s.max_pages: Valid with &memory_group.is_dynamic == false. The maximum
* number of pages we'll have in this static memory group.
* @d.unit_pages: Valid with &memory_group.is_dynamic == true. Unit in pages
* in which memory is added/removed in this dynamic memory group.
* This granularity defines the alignment of a unit in physical
* address space; it has to be at least as big as a single
* memory block.
* A memory group logically groups memory blocks; each memory block
* belongs to at most one memory group. A memory group corresponds to
* a memory device, such as a DIMM or a NUMA node, which spans multiple
* memory blocks and might even span multiple non-contiguous physical memory
* ranges.
* Modification of members after registration is serialized by memory
* hot(un)plug code.
struct memory_group {
int nid;
struct list_head memory_blocks;
unsigned long present_kernel_pages;
unsigned long present_movable_pages;
bool is_dynamic;
union {
struct {
unsigned long max_pages;
} s;
struct {
unsigned long unit_pages;
} d;
struct memory_block {
unsigned long start_section_nr;
unsigned long state; /* serialized by the dev->lock */
int online_type; /* for passing data to online routine */
int nid; /* NID for this memory block */
struct device dev;
* Number of vmemmap pages. These pages
* lay at the beginning of the memory block.
unsigned long nr_vmemmap_pages;
struct memory_group *group; /* group (if any) for this block */
struct list_head group_next; /* next block inside memory group */
int arch_get_memory_phys_device(unsigned long start_pfn);
unsigned long memory_block_size_bytes(void);
int set_memory_block_size_order(unsigned int order);
/* These states are exposed to userspace as text strings in sysfs */
#define MEM_ONLINE (1<<0) /* exposed to userspace */
#define MEM_GOING_OFFLINE (1<<1) /* exposed to userspace */
#define MEM_OFFLINE (1<<2) /* exposed to userspace */
#define MEM_GOING_ONLINE (1<<3)
#define MEM_CANCEL_ONLINE (1<<4)
#define MEM_CANCEL_OFFLINE (1<<5)
struct memory_notify {
unsigned long start_pfn;
unsigned long nr_pages;
int status_change_nid_normal;
int status_change_nid;
struct notifier_block;
struct mem_section;
* Priorities for the hotplug memory callback routines (stored in decreasing
* order in the callback chain)
static inline void memory_dev_init(void)
static inline int register_memory_notifier(struct notifier_block *nb)
return 0;
static inline void unregister_memory_notifier(struct notifier_block *nb)
static inline int memory_notify(unsigned long val, void *v)
return 0;
static inline int hotplug_memory_notifier(notifier_fn_t fn, int pri)
return 0;
/* These aren't inline functions due to a GCC bug. */
#define register_hotmemory_notifier(nb) ({ (void)(nb); 0; })
#define unregister_hotmemory_notifier(nb) ({ (void)(nb); })
extern int register_memory_notifier(struct notifier_block *nb);
extern void unregister_memory_notifier(struct notifier_block *nb);
int create_memory_block_devices(unsigned long start, unsigned long size,
unsigned long vmemmap_pages,
struct memory_group *group);
void remove_memory_block_devices(unsigned long start, unsigned long size);
extern void memory_dev_init(void);
extern int memory_notify(unsigned long val, void *v);
extern struct memory_block *find_memory_block(unsigned long section_nr);
typedef int (*walk_memory_blocks_func_t)(struct memory_block *, void *);
extern int walk_memory_blocks(unsigned long start, unsigned long size,
void *arg, walk_memory_blocks_func_t func);
extern int for_each_memory_block(void *arg, walk_memory_blocks_func_t func);
extern int memory_group_register_static(int nid, unsigned long max_pages);
extern int memory_group_register_dynamic(int nid, unsigned long unit_pages);
extern int memory_group_unregister(int mgid);
struct memory_group *memory_group_find_by_id(int mgid);
typedef int (*walk_memory_groups_func_t)(struct memory_group *, void *);
int walk_dynamic_memory_groups(int nid, walk_memory_groups_func_t func,
struct memory_group *excluded, void *arg);
#define hotplug_memory_notifier(fn, pri) ({ \
static __meminitdata struct notifier_block fn##_mem_nb =\
{ .notifier_call = fn, .priority = pri };\
register_memory_notifier(&fn##_mem_nb); \
#define register_hotmemory_notifier(nb) register_memory_notifier(nb)
#define unregister_hotmemory_notifier(nb) unregister_memory_notifier(nb)
* Kernel text modification mutex, used for code patching. Users of this lock
* can sleep.
extern struct mutex text_mutex;
#endif /* _LINUX_MEMORY_H_ */