[RFC][PATCH 08/12] memory hotplug: sysfs and add/remove functions

From: Dave Hansen (haveblue_at_us.ibm.com)
Date: 08/12/05

  • Next message: Andi Kleen: "Re: APIC version and 8-bit APIC IDs"
    To: linux-kernel@vger.kernel.org
    Date:	Fri, 12 Aug 2005 07:47:28 -0700
    
    

    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: Matt Tolentino <matthew.e.tolentino@intel.com>
    Signed-off-by: Dave Hansen <haveblue@us.ibm.com>

    ---
     memhotplug-dave/drivers/base/Makefile          |    1 
     memhotplug-dave/drivers/base/init.c            |    2 
     memhotplug-dave/drivers/base/memory.c          |  455 +++++++++++++++++++++++++
     memhotplug-dave/include/linux/memory.h         |   94 +++++
     memhotplug-dave/include/linux/memory_hotplug.h |   35 +
     memhotplug-dave/include/linux/mm.h             |    1 
     memhotplug-dave/mm/Kconfig                     |    8 
     memhotplug-dave/mm/Makefile                    |    2 
     memhotplug-dave/mm/memory_hotplug.c            |  178 +++++++++
     memhotplug-dave/mm/page_alloc.c                |    4 
     mm/sparse.c                                    |    0 
     11 files changed, 777 insertions(+), 3 deletions(-)
    diff -puN drivers/base/Makefile~D0-sysfs-memory-class drivers/base/Makefile
    --- memhotplug/drivers/base/Makefile~D0-sysfs-memory-class	2005-08-12 07:43:48.000000000 -0700
    +++ memhotplug-dave/drivers/base/Makefile	2005-08-12 07:43:48.000000000 -0700
    @@ -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
     
     ifeq ($(CONFIG_DEBUG_DRIVER),y)
     EXTRA_CFLAGS += -DDEBUG
    diff -puN drivers/base/init.c~D0-sysfs-memory-class drivers/base/init.c
    --- memhotplug/drivers/base/init.c~D0-sysfs-memory-class	2005-08-12 07:43:48.000000000 -0700
    +++ memhotplug-dave/drivers/base/init.c	2005-08-12 07:43:48.000000000 -0700
    @@ -9,6 +9,7 @@
     
     #include <linux/device.h>
     #include <linux/init.h>
    +#include <linux/memory.h>
     
     extern int devices_init(void);
     extern int buses_init(void);
    @@ -39,5 +40,6 @@ void __init driver_init(void)
     	platform_bus_init();
     	system_bus_init();
     	cpu_dev_init();
    +	memory_dev_init();
     	attribute_container_init();
     }
    diff -puN /dev/null drivers/base/memory.c
    --- /dev/null	2005-03-30 22:36:15.000000000 -0800
    +++ memhotplug-dave/drivers/base/memory.c	2005-08-12 07:43:48.000000000 -0700
    @@ -0,0 +1,455 @@
    +/*
    + * drivers/base/memory.c - basic Memory class support
    + *
    + * Written by Matt Tolentino <matthew.e.tolentino@intel.com>
    + *            Dave Hansen <haveblue@us.ibm.com>
    + *
    + * This file provides the necessary infrastructure to represent
    + * a SPARSEMEM-memory-model system's physical memory in /sysfs.
    + * All arch-independent code that assumes MEMORY_HOTPLUG requires
    + * SPARSEMEM should be contained here, or in mm/memory_hotplug.c.
    + */
    +
    +#include <linux/sysdev.h>
    +#include <linux/module.h>
    +#include <linux/init.h>
    +#include <linux/sched.h>	/* capable() */
    +#include <linux/topology.h>
    +#include <linux/device.h>
    +#include <linux/memory.h>
    +#include <linux/kobject.h>
    +#include <linux/memory_hotplug.h>
    +#include <linux/mm.h>
    +#include <asm/atomic.h>
    +#include <asm/uaccess.h>
    +
    +#define MEMORY_CLASS_NAME	"memory"
    +
    +struct sysdev_class memory_sysdev_class = {
    +	set_kset_name(MEMORY_CLASS_NAME),
    +};
    +EXPORT_SYMBOL(memory_sysdev_class);
    +
    +static char *memory_hotplug_name(struct kset *kset, struct kobject *kobj)
    +{
    +	return MEMORY_CLASS_NAME;
    +}
    +
    +static int memory_hotplug(struct kset *kset, struct kobject *kobj, char **envp,
    +			int num_envp, char *buffer, int buffer_size)
    +{
    +	int retval = 0;
    +
    +	return retval;
    +}
    +
    +static struct kset_hotplug_ops memory_hotplug_ops = {
    +	.name		= memory_hotplug_name,
    +	.hotplug	= memory_hotplug,
    +};
    +
    +static struct notifier_block *memory_chain;
    +
    +int register_memory_notifier(struct notifier_block *nb)
    +{
    +        return notifier_chain_register(&memory_chain, nb);
    +}
    +
    +void unregister_memory_notifier(struct notifier_block *nb)
    +{
    +        notifier_chain_unregister(&memory_chain, nb);
    +}
    +
    +/*
    + * register_memory - Setup a sysfs device for a memory block
    + */
    +int
    +register_memory(struct memory_block *memory, struct mem_section *section,
    +		struct node *root)
    +{
    +	int error;
    +
    +	memory->sysdev.cls = &memory_sysdev_class;
    +	memory->sysdev.id = __section_nr(section);
    +
    +	error = sysdev_register(&memory->sysdev);
    +
    +	if (root && !error)
    +		error = sysfs_create_link(&root->sysdev.kobj,
    +					  &memory->sysdev.kobj,
    +					  kobject_name(&memory->sysdev.kobj));
    +
    +	return error;
    +}
    +
    +void
    +unregister_memory(struct memory_block *memory, struct mem_section *section,
    +		struct node *root)
    +{
    +	BUG_ON(memory->sysdev.cls != &memory_sysdev_class);
    +	BUG_ON(memory->sysdev.id != __section_nr(section));
    +
    +	sysdev_unregister(&memory->sysdev);
    +	if (root)
    +		sysfs_remove_link(&root->sysdev.kobj,
    +				  kobject_name(&memory->sysdev.kobj));
    +}
    +
    +/*
    + * use this as the physical section index that this memsection
    + * uses.
    + */
    +
    +static ssize_t show_mem_phys_index(struct sys_device *dev, char *buf)
    +{
    +	struct memory_block *mem =
    +		container_of(dev, struct memory_block, sysdev);
    +	return sprintf(buf, "%08lx\n", mem->phys_index);
    +}
    +
    +/*
    + * online, offline, going offline, etc.
    + */
    +static ssize_t show_mem_state(struct sys_device *dev, char *buf)
    +{
    +	struct memory_block *mem =
    +		container_of(dev, struct memory_block, sysdev);
    +	ssize_t len = 0;
    +
    +	/*
    +	 * We can probably put these states in a nice little array
    +	 * so that they're not open-coded
    +	 */
    +	switch (mem->state) {
    +		case MEM_ONLINE:
    +			len = sprintf(buf, "online\n");
    +			break;
    +		case MEM_OFFLINE:
    +			len = sprintf(buf, "offline\n");
    +			break;
    +		case MEM_GOING_OFFLINE:
    +			len = sprintf(buf, "going-offline\n");
    +			break;
    +		default:
    +			len = sprintf(buf, "ERROR-UNKNOWN-%ld\n",
    +					mem->state);
    +			WARN_ON(1);
    +			break;
    +	}
    +
    +	return len;
    +}
    +
    +static inline int memory_notify(unsigned long val, void *v)
    +{
    +	return notifier_call_chain(&memory_chain, val, v);
    +}
    +
    +/*
    + * MEMORY_HOTPLUG depends on SPARSEMEM in mm/Kconfig, so it is
    + * OK to have direct references to sparsemem variables in here.
    + */
    +static int
    +memory_block_action(struct memory_block *mem, unsigned long action)
    +{
    +	int i;
    +	unsigned long psection;
    +	unsigned long start_pfn, start_paddr;
    +	struct page *first_page;
    +	int ret;
    +	int old_state = mem->state;
    +
    +	psection = mem->phys_index;
    +	first_page = pfn_to_page(psection << PFN_SECTION_SHIFT);
    +
    +	/*
    +	 * The probe routines leave the pages reserved, just
    +	 * as the bootmem code does.  Make sure they're still
    +	 * that way.
    +	 */
    +	if (action == MEM_ONLINE) {
    +		for (i = 0; i < PAGES_PER_SECTION; i++) {
    +			if (PageReserved(first_page+i))
    +				continue;
    +
    +			printk(KERN_WARNING "section number %ld page number %d "
    +				"not reserved, was it already online? \n",
    +				psection, i);
    +			return -EBUSY;
    +		}
    +	}
    +
    +	switch (action) {
    +		case MEM_ONLINE:
    +			start_pfn = page_to_pfn(first_page);
    +			ret = online_pages(start_pfn, PAGES_PER_SECTION);
    +			break;
    +		case MEM_OFFLINE:
    +			mem->state = MEM_GOING_OFFLINE;
    +			memory_notify(MEM_GOING_OFFLINE, NULL);
    +			start_paddr = page_to_pfn(first_page) << PAGE_SHIFT;
    +			ret = remove_memory(start_paddr,
    +					    PAGES_PER_SECTION << PAGE_SHIFT);
    +			if (ret) {
    +				mem->state = old_state;
    +				break;
    +			}
    +			memory_notify(MEM_MAPPING_INVALID, NULL);
    +			break;
    +		default:
    +			printk(KERN_WARNING "%s(%p, %ld) unknown action: %ld\n",
    +					__FUNCTION__, mem, action, action);
    +			WARN_ON(1);
    +			ret = -EINVAL;
    +	}
    +	/*
    +	 * For now, only notify on successful memory operations
    +	 */
    +	if (!ret)
    +		memory_notify(action, NULL);
    +
    +	return ret;
    +}
    +
    +static int memory_block_change_state(struct memory_block *mem,
    +		unsigned long to_state, unsigned long from_state_req)
    +{
    +	int ret = 0;
    +	down(&mem->state_sem);
    +
    +	if (mem->state != from_state_req) {
    +		ret = -EINVAL;
    +		goto out;
    +	}
    +
    +	ret = memory_block_action(mem, to_state);
    +	if (!ret)
    +		mem->state = to_state;
    +
    +out:
    +	up(&mem->state_sem);
    +	return ret;
    +}
    +
    +static ssize_t
    +store_mem_state(struct sys_device *dev, const char *buf, size_t count)
    +{
    +	struct memory_block *mem;
    +	unsigned int phys_section_nr;
    +	int ret = -EINVAL;
    +
    +	mem = container_of(dev, struct memory_block, sysdev);
    +	phys_section_nr = mem->phys_index;
    +
    +	if (!valid_section_nr(phys_section_nr))
    +		goto out;
    +
    +	if (!strncmp(buf, "online", min((int)count, 6)))
    +		ret = memory_block_change_state(mem, MEM_ONLINE, MEM_OFFLINE);
    +	else if(!strncmp(buf, "offline", min((int)count, 7)))
    +		ret = memory_block_change_state(mem, MEM_OFFLINE, MEM_ONLINE);
    +out:
    +	if (ret)
    +		return ret;
    +	return count;
    +}
    +
    +/*
    + * phys_device is a bad name for this.  What I really want
    + * is a way to differentiate between memory ranges that
    + * are part of physical devices that constitute
    + * a complete removable unit or fru.
    + * i.e. do these ranges belong to the same physical device,
    + * s.t. if I offline all of these sections I can then
    + * remove the physical device?
    + */
    +static ssize_t show_phys_device(struct sys_device *dev, char *buf)
    +{
    +	struct memory_block *mem =
    +		container_of(dev, struct memory_block, sysdev);
    +	return sprintf(buf, "%d\n", mem->phys_device);
    +}
    +
    +SYSDEV_ATTR(phys_index, 0444, show_mem_phys_index, NULL);
    +SYSDEV_ATTR(state, 0644, show_mem_state, store_mem_state);
    +SYSDEV_ATTR(phys_device, 0444, show_phys_device, NULL);
    +
    +#define mem_create_simple_file(mem, attr_name)	\
    +	sysdev_create_file(&mem->sysdev, &attr_##attr_name)
    +#define mem_remove_simple_file(mem, attr_name)	\
    +	sysdev_remove_file(&mem->sysdev, &attr_##attr_name)
    +
    +/*
    + * Block size attribute stuff
    + */
    +static ssize_t
    +print_block_size(struct class *class, char *buf)
    +{
    +	return sprintf(buf, "%lx\n", (unsigned long)PAGES_PER_SECTION * PAGE_SIZE);
    +}
    +
    +static CLASS_ATTR(block_size_bytes, 0444, print_block_size, NULL);
    +
    +static int block_size_init(void)
    +{
    +	sysfs_create_file(&memory_sysdev_class.kset.kobj,
    +		&class_attr_block_size_bytes.attr);
    +	return 0;
    +}
    +
    +/*
    + * Some architectures will have custom drivers to do this, and
    + * will not need to do it from userspace.  The fake hot-add code
    + * as well as ppc64 will do all of their discovery in userspace
    + * and will require this interface.
    + */
    +#ifdef CONFIG_ARCH_MEMORY_PROBE
    +static ssize_t
    +memory_probe_store(struct class *class, const char __user *buf, size_t count)
    +{
    +	u64 phys_addr;
    +	int ret;
    +
    +	phys_addr = simple_strtoull(buf, NULL, 0);
    +
    +	ret = add_memory(phys_addr, PAGES_PER_SECTION << PAGE_SHIFT);
    +
    +	if (ret)
    +		count = ret;
    +
    +	return count;
    +}
    +static CLASS_ATTR(probe, 0700, NULL, memory_probe_store);
    +
    +static int memory_probe_init(void)
    +{
    +	sysfs_create_file(&memory_sysdev_class.kset.kobj,
    +		&class_attr_probe.attr);
    +	return 0;
    +}
    +#else
    +#define memory_probe_init(...)	do {} while (0)
    +#endif
    +
    +/*
    + * Note that phys_device is optional.  It is here to allow for
    + * differentiation between which *physical* devices each
    + * section belongs to...
    + */
    +
    +int add_memory_block(unsigned long node_id, struct mem_section *section,
    +		     unsigned long state, int phys_device)
    +{
    +	size_t size = sizeof(struct memory_block);
    +	struct memory_block *mem = kmalloc(size, GFP_KERNEL);
    +	int ret = 0;
    +
    +	if (!mem)
    +		return -ENOMEM;
    +
    +	memset(mem, 0, size);
    +
    +	mem->phys_index = __section_nr(section);
    +	mem->state = state;
    +	init_MUTEX(&mem->state_sem);
    +	mem->phys_device = phys_device;
    +
    +	ret = register_memory(mem, section, NULL);
    +	if (!ret)
    +		ret = mem_create_simple_file(mem, phys_index);
    +	if (!ret)
    +		ret = mem_create_simple_file(mem, state);
    +	if (!ret)
    +		ret = mem_create_simple_file(mem, phys_device);
    +
    +	return ret;
    +}
    +
    +/*
    + * For now, we have a linear search to go find the appropriate
    + * memory_block corresponding to a particular phys_index. If
    + * this gets to be a real problem, we can always use a radix
    + * tree or something here.
    + *
    + * This could be made generic for all sysdev classes.
    + */
    +struct memory_block *find_memory_block(struct mem_section *section)
    +{
    +	struct kobject *kobj;
    +	struct sys_device *sysdev;
    +	struct memory_block *mem;
    +	char name[sizeof(MEMORY_CLASS_NAME) + 9 + 1];
    +
    +	/*
    +	 * This only works because we know that section == sysdev->id
    +	 * slightly redundant with sysdev_register()
    +	 */
    +	sprintf(&name[0], "%s%d", MEMORY_CLASS_NAME, __section_nr(section));
    +
    +	kobj = kset_find_obj(&memory_sysdev_class.kset, name);
    +	if (!kobj)
    +		return NULL;
    +
    +	sysdev = container_of(kobj, struct sys_device, kobj);
    +	mem = container_of(sysdev, struct memory_block, sysdev);
    +
    +	return mem;
    +}
    +
    +int remove_memory_block(unsigned long node_id, struct mem_section *section,
    +		int phys_device)
    +{
    +	struct memory_block *mem;
    +
    +	mem = find_memory_block(section);
    +	mem_remove_simple_file(mem, phys_index);
    +	mem_remove_simple_file(mem, state);
    +	mem_remove_simple_file(mem, phys_device);
    +	unregister_memory(mem, section, NULL);
    +
    +	return 0;
    +}
    +
    +/*
    + * need an interface for the VM to add new memory regions,
    + * but without onlining it.
    + */
    +int register_new_memory(struct mem_section *section)
    +{
    +	return add_memory_block(0, section, MEM_OFFLINE, 0);
    +}
    +
    +int unregister_memory_section(struct mem_section *section)
    +{
    +	if (!valid_section(section))
    +		return -EINVAL;
    +
    +	return remove_memory_block(0, section, 0);
    +}
    +
    +/*
    + * Initialize the sysfs support for memory devices...
    + */
    +int __init memory_dev_init(void)
    +{
    +	unsigned int i;
    +	int ret;
    +
    +	memory_sysdev_class.kset.hotplug_ops = &memory_hotplug_ops;
    +	ret = sysdev_class_register(&memory_sysdev_class);
    +
    +	/*
    +	 * Create entries for memory sections that were found
    +	 * during boot and have been initialized
    +	 */
    +	for (i = 0; i < NR_MEM_SECTIONS; i++) {
    +		if (!valid_section_nr(i))
    +			continue;
    +		add_memory_block(0, __nr_to_section(i), MEM_ONLINE, 0);
    +	}
    +
    +	memory_probe_init();
    +	block_size_init();
    +
    +	return ret;
    +}
    diff -puN include/asm-i386/highmem.h~D0-sysfs-memory-class include/asm-i386/highmem.h
    diff -puN /dev/null include/linux/memory.h
    --- /dev/null	2005-03-30 22:36:15.000000000 -0800
    +++ memhotplug-dave/include/linux/memory.h	2005-08-12 07:43:48.000000000 -0700
    @@ -0,0 +1,94 @@
    +/*
    + * 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)
    +
    +#ifndef CONFIG_MEMORY_HOTPLUG
    +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)
    +{
    +}
    +#else
    +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);
    +
    +#define CONFIG_MEM_BLOCK_SIZE	(PAGES_PER_SECTION<<PAGE_SHIFT)
    +
    +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;
    +#endif /* CONFIG_MEMORY_HOTPLUG */
    +
    +#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_ */
    diff -puN include/linux/memory_hotplug.h~D0-sysfs-memory-class include/linux/memory_hotplug.h
    --- memhotplug/include/linux/memory_hotplug.h~D0-sysfs-memory-class	2005-08-12 07:43:48.000000000 -0700
    +++ memhotplug-dave/include/linux/memory_hotplug.h	2005-08-12 07:43:48.000000000 -0700
    @@ -3,6 +3,8 @@
     
     #include <linux/mmzone.h>
     #include <linux/spinlock.h>
    +#include <linux/mmzone.h>
    +#include <linux/notifier.h>
     
     #ifdef CONFIG_MEMORY_HOTPLUG
     /*
    @@ -46,6 +48,19 @@ static inline void zone_seqlock_init(str
     {
     	seqlock_init(&zone->span_seqlock);
     }
    +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);
     #else /* ! CONFIG_MEMORY_HOTPLUG */
     /*
      * Stub functions for when hotplug is off
    @@ -65,5 +80,25 @@ static inline int zone_span_seqretry(str
     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);
    +	dump_stack();
    +	return -ENOSYS;
    +}
    +
    +static inline int __add_pages(struct zone *zone, unsigned long start_pfn,
    +	unsigned long nr_pages)
    +{
    +	return mhp_notimplemented(__FUNCTION__);
    +}
     #endif /* ! CONFIG_MEMORY_HOTPLUG */
    +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__);
    +	dump_stack();
    +	return -ENOSYS;
    +}
     #endif /* __LINUX_MEMORY_HOTPLUG_H */
    diff -puN mm/Kconfig~D0-sysfs-memory-class mm/Kconfig
    --- memhotplug/mm/Kconfig~D0-sysfs-memory-class	2005-08-12 07:43:48.000000000 -0700
    +++ memhotplug-dave/mm/Kconfig	2005-08-12 07:43:48.000000000 -0700
    @@ -111,3 +111,11 @@ config SPARSEMEM_STATIC
     config SPARSEMEM_EXTREME
     	def_bool y
     	depends on SPARSEMEM && !SPARSEMEM_STATIC
    +
    +# eventually, we can have this option just 'select SPARSEMEM'
    +config MEMORY_HOTPLUG
    +	bool "Allow for memory hot-add"
    +	depends on SPARSEMEM && HOTPLUG && !SOFTWARE_SUSPEND
    +
    +comment "Memory hotplug is currently incompatible with Software Suspend"
    +	depends on SPARSEMEM && HOTPLUG && SOFTWARE_SUSPEND
    diff -puN mm/Makefile~D0-sysfs-memory-class mm/Makefile
    --- memhotplug/mm/Makefile~D0-sysfs-memory-class	2005-08-12 07:43:48.000000000 -0700
    +++ memhotplug-dave/mm/Makefile	2005-08-12 07:43:48.000000000 -0700
    @@ -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
    diff -puN /dev/null mm/memory_hotplug.c
    --- /dev/null	2005-03-30 22:36:15.000000000 -0800
    +++ memhotplug-dave/mm/memory_hotplug.c	2005-08-12 07:43:48.000000000 -0700
    @@ -0,0 +1,178 @@
    +/*
    + *  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;
    +got_map_page:
    +	ret = (struct page *)pfn_to_kaddr(page_to_pfn(page));
    +got_map_ptr:
    +	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);
    +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)
    +			vfree(memmap);
    +		else
    +			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)
    +			break;
    +	}
    +
    +	return err;
    +}
    +
    +static void grow_zone_span(struct zone *zone,
    +		unsigned long start_pfn, unsigned long end_pfn)
    +{
    +	unsigned long old_zone_end_pfn;
    +
    +	zone_span_writelock(zone);
    +
    +	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;
    +
    +	zone_span_writeunlock(zone);
    +}
    +
    +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);
    +		online_page(page);
    +		onlined_pages++;
    +	}
    +	zone->present_pages += onlined_pages;
    +
    +	return 0;
    +}
    diff -puN mm/page_alloc.c~D0-sysfs-memory-class mm/page_alloc.c
    --- memhotplug/mm/page_alloc.c~D0-sysfs-memory-class	2005-08-12 07:43:48.000000000 -0700
    +++ memhotplug-dave/mm/page_alloc.c	2005-08-12 07:43:48.000000000 -0700
    @@ -1663,7 +1663,7 @@ static void __init calculate_zone_totalp
      * 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;
    @@ -2386,7 +2386,7 @@ static void setup_per_zone_lowmem_reserv
      *	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;
    diff -puN include/linux/mm.h~D0-sysfs-memory-class include/linux/mm.h
    --- memhotplug/include/linux/mm.h~D0-sysfs-memory-class	2005-08-12 07:43:48.000000000 -0700
    +++ memhotplug-dave/include/linux/mm.h	2005-08-12 07:43:48.000000000 -0700
    @@ -791,6 +791,7 @@ extern void free_area_init_node(int nid,
     	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);
    diff -puN mm/sparse.c~D0-sysfs-memory-class mm/sparse.c
    _
    -
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