Commit 3947be19 authored by Dave Hansen's avatar Dave Hansen Committed by Linus Torvalds

[PATCH] memory hotplug: sysfs and add/remove functions

This adds generic memory add/remove and supporting functions for memory
hotplug into a new file as well as a memory hotplug kernel config option.

Individual architecture patches will follow.

For now, disable memory hotplug when swsusp is enabled.  There's a lot of
churn there right now.  We'll fix it up properly once it calms down.
Signed-off-by: default avatarMatt Tolentino <>
Signed-off-by: default avatarDave Hansen <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent bdc8cb98
......@@ -7,6 +7,7 @@ obj-y := core.o sys.o bus.o dd.o \
obj-y += power/
obj-$(CONFIG_FW_LOADER) += firmware_class.o
obj-$(CONFIG_NUMA) += node.o
obj-$(CONFIG_MEMORY_HOTPLUG) += memory.o
......@@ -9,6 +9,7 @@
#include <linux/device.h>
#include <linux/init.h>
#include <linux/memory.h>
#include "base.h"
......@@ -33,5 +34,6 @@ void __init driver_init(void)
This diff is collapsed.
* 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/sysdev.h>
#include <linux/node.h>
#include <linux/compiler.h>
#include <asm/semaphore.h>
struct memory_block {
unsigned long phys_index;
unsigned long state;
* This serializes all state change requests. It isn't
* held during creation because the control files are
* created long after the critical areas during
* initialization.
struct semaphore state_sem;
int phys_device; /* to which fru does this belong? */
void *hw; /* optional pointer to fw/hw data */
int (*phys_callback)(struct memory_block *);
struct sys_device sysdev;
/* 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 */
* All of these states are currently kernel-internal for notifying
* kernel components and architectures.
* For MEM_MAPPING_INVALID, all notifier chains with priority >0
* are called before pfn_to_page() becomes invalid. The priority=0
* entry is reserved for the function that actually makes
* pfn_to_page() stop working. Any notifiers that want to be called
* after that should have priority <0.
#define MEM_MAPPING_INVALID (1<<3)
static inline int memory_dev_init(void)
return 0;
static inline int register_memory_notifier(struct notifier_block *nb)
return 0;
static inline void unregister_memory_notifier(struct notifier_block *nb)
extern int register_memory(struct memory_block *, struct mem_section *section, struct node *);
extern int register_new_memory(struct mem_section *);
extern int unregister_memory_section(struct mem_section *);
extern int memory_dev_init(void);
extern int register_memory_notifier(struct notifier_block *nb);
extern void unregister_memory_notifier(struct notifier_block *nb);
extern int invalidate_phys_mapping(unsigned long, unsigned long);
struct notifier_block;
extern int register_memory_notifier(struct notifier_block *nb);
extern void unregister_memory_notifier(struct notifier_block *nb);
extern struct sysdev_class memory_sysdev_class;
#define hotplug_memory_notifier(fn, pri) { \
static struct notifier_block fn##_mem_nb = \
{ .notifier_call = fn, .priority = pri }; \
register_memory_notifier(&fn##_mem_nb); \
#endif /* _LINUX_MEMORY_H_ */
......@@ -3,6 +3,8 @@
#include <linux/mmzone.h>
#include <linux/spinlock.h>
#include <linux/mmzone.h>
#include <linux/notifier.h>
......@@ -46,6 +48,19 @@ static inline void zone_seqlock_init(struct zone *zone)
extern int zone_grow_free_lists(struct zone *zone, unsigned long new_nr_pages);
extern int zone_grow_waitqueues(struct zone *zone, unsigned long nr_pages);
extern int add_one_highpage(struct page *page, int pfn, int bad_ppro);
/* need some defines for these for archs that don't support it */
extern void online_page(struct page *page);
/* VM interface that may be used by firmware interface */
extern int add_memory(u64 start, u64 size);
extern int remove_memory(u64 start, u64 size);
extern int online_pages(unsigned long, unsigned long);
/* reasonably generic interface to expand the physical pages in a zone */
extern int __add_pages(struct zone *zone, unsigned long start_pfn,
unsigned long nr_pages);
* Stub functions for when hotplug is off
......@@ -65,5 +80,25 @@ static inline int zone_span_seqretry(struct zone *zone, unsigned iv)
static inline void zone_span_writelock(struct zone *zone) {}
static inline void zone_span_writeunlock(struct zone *zone) {}
static inline void zone_seqlock_init(struct zone *zone) {}
static inline int mhp_notimplemented(const char *func)
printk(KERN_WARNING "%s() called, with CONFIG_MEMORY_HOTPLUG disabled\n", func);
return -ENOSYS;
static inline int __add_pages(struct zone *zone, unsigned long start_pfn,
unsigned long nr_pages)
return mhp_notimplemented(__FUNCTION__);
static inline int __remove_pages(struct zone *zone, unsigned long start_pfn,
unsigned long nr_pages)
printk(KERN_WARNING "%s() called, not yet supported\n", __FUNCTION__);
return -ENOSYS;
......@@ -840,6 +840,7 @@ extern void free_area_init_node(int nid, pg_data_t *pgdat,
unsigned long * zones_size, unsigned long zone_start_pfn,
unsigned long *zholes_size);
extern void memmap_init_zone(unsigned long, int, unsigned long, unsigned long);
extern void setup_per_zone_pages_min(void);
extern void mem_init(void);
extern void show_mem(void);
extern void si_meminfo(struct sysinfo * val);
......@@ -112,6 +112,14 @@ config SPARSEMEM_EXTREME
def_bool y
# eventually, we can have this option just 'select SPARSEMEM'
bool "Allow for memory hot-add"
comment "Memory hotplug is currently incompatible with Software Suspend"
# Heavily threaded applications may benefit from splitting the mm-wide
# page_table_lock, so that faults on different parts of the user address
# space can be handled with less contention: split it at this NR_CPUS.
......@@ -18,5 +18,5 @@ obj-$(CONFIG_NUMA) += mempolicy.o
obj-$(CONFIG_SPARSEMEM) += sparse.o
obj-$(CONFIG_SHMEM) += shmem.o
obj-$(CONFIG_TINY_SHMEM) += tiny-shmem.o
obj-$(CONFIG_MEMORY_HOTPLUG) += memory_hotplug.o
obj-$(CONFIG_FS_XIP) += filemap_xip.o
* linux/mm/memory_hotplug.c
* Copyright (C)
#include <linux/config.h>
#include <linux/stddef.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/interrupt.h>
#include <linux/pagemap.h>
#include <linux/bootmem.h>
#include <linux/compiler.h>
#include <linux/module.h>
#include <linux/pagevec.h>
#include <linux/slab.h>
#include <linux/sysctl.h>
#include <linux/cpu.h>
#include <linux/memory.h>
#include <linux/memory_hotplug.h>
#include <linux/highmem.h>
#include <linux/vmalloc.h>
#include <asm/tlbflush.h>
static struct page *__kmalloc_section_memmap(unsigned long nr_pages)
struct page *page, *ret;
unsigned long memmap_size = sizeof(struct page) * nr_pages;
page = alloc_pages(GFP_KERNEL, get_order(memmap_size));
if (page)
goto got_map_page;
ret = vmalloc(memmap_size);
if (ret)
goto got_map_ptr;
return NULL;
ret = (struct page *)pfn_to_kaddr(page_to_pfn(page));
memset(ret, 0, memmap_size);
return ret;
extern void zonetable_add(struct zone *zone, int nid, int zid, unsigned long pfn,
unsigned long size);
static void __add_zone(struct zone *zone, unsigned long phys_start_pfn)
struct pglist_data *pgdat = zone->zone_pgdat;
int nr_pages = PAGES_PER_SECTION;
int nid = pgdat->node_id;
int zone_type;
zone_type = zone - pgdat->node_zones;
memmap_init_zone(nr_pages, nid, zone_type, phys_start_pfn);
zonetable_add(zone, nid, zone_type, phys_start_pfn, nr_pages);
extern int sparse_add_one_section(struct zone *, unsigned long,
struct page *mem_map);
static int __add_section(struct zone *zone, unsigned long phys_start_pfn)
struct pglist_data *pgdat = zone->zone_pgdat;
int nr_pages = PAGES_PER_SECTION;
struct page *memmap;
int ret;
* This can potentially allocate memory, and does its own
* internal locking.
sparse_index_init(pfn_to_section_nr(phys_start_pfn), pgdat->node_id);
pgdat_resize_lock(pgdat, &flags);
memmap = __kmalloc_section_memmap(nr_pages);
ret = sparse_add_one_section(zone, phys_start_pfn, memmap);
pgdat_resize_unlock(pgdat, &flags);
if (ret <= 0) {
/* the mem_map didn't get used */
if (memmap >= (struct page *)VMALLOC_START &&
memmap < (struct page *)VMALLOC_END)
free_pages((unsigned long)memmap,
get_order(sizeof(struct page) * nr_pages));
if (ret < 0)
return ret;
__add_zone(zone, phys_start_pfn);
return register_new_memory(__pfn_to_section(phys_start_pfn));
* Reasonably generic function for adding memory. It is
* expected that archs that support memory hotplug will
* call this function after deciding the zone to which to
* add the new pages.
int __add_pages(struct zone *zone, unsigned long phys_start_pfn,
unsigned long nr_pages)
unsigned long i;
int err = 0;
for (i = 0; i < nr_pages; i += PAGES_PER_SECTION) {
err = __add_section(zone, phys_start_pfn + i);
if (err)
return err;
static void grow_zone_span(struct zone *zone,
unsigned long start_pfn, unsigned long end_pfn)
unsigned long old_zone_end_pfn;
old_zone_end_pfn = zone->zone_start_pfn + zone->spanned_pages;
if (start_pfn < zone->zone_start_pfn)
zone->zone_start_pfn = start_pfn;
if (end_pfn > old_zone_end_pfn)
zone->spanned_pages = end_pfn - zone->zone_start_pfn;
static void grow_pgdat_span(struct pglist_data *pgdat,
unsigned long start_pfn, unsigned long end_pfn)
unsigned long old_pgdat_end_pfn =
pgdat->node_start_pfn + pgdat->node_spanned_pages;
if (start_pfn < pgdat->node_start_pfn)
pgdat->node_start_pfn = start_pfn;
if (end_pfn > old_pgdat_end_pfn)
pgdat->node_spanned_pages = end_pfn - pgdat->node_spanned_pages;
int online_pages(unsigned long pfn, unsigned long nr_pages)
unsigned long i;
unsigned long flags;
unsigned long onlined_pages = 0;
struct zone *zone;
* This doesn't need a lock to do pfn_to_page().
* The section can't be removed here because of the
* memory_block->state_sem.
zone = page_zone(pfn_to_page(pfn));
pgdat_resize_lock(zone->zone_pgdat, &flags);
grow_zone_span(zone, pfn, pfn + nr_pages);
grow_pgdat_span(zone->zone_pgdat, pfn, pfn + nr_pages);
pgdat_resize_unlock(zone->zone_pgdat, &flags);
for (i = 0; i < nr_pages; i++) {
struct page *page = pfn_to_page(pfn + i);
zone->present_pages += onlined_pages;
return 0;
......@@ -1686,7 +1686,7 @@ static void __init calculate_zone_totalpages(struct pglist_data *pgdat,
* up by free_all_bootmem() once the early boot process is
* done. Non-atomic initialization, single-pass.
void __init memmap_init_zone(unsigned long size, int nid, unsigned long zone,
void __devinit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
unsigned long start_pfn)
struct page *page;
......@@ -2407,7 +2407,7 @@ static void setup_per_zone_lowmem_reserve(void)
* that the pages_{min,low,high} values for each zone are set correctly
* with respect to min_free_kbytes.
static void setup_per_zone_pages_min(void)
void setup_per_zone_pages_min(void)
unsigned long pages_min = min_free_kbytes >> (PAGE_SHIFT - 10);
unsigned long lowmem_pages = 0;
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