1 files changed, 412 insertions, 243 deletions

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index d7d77d4a402..89f752dd846 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -1,5 +1,5 @@
 /*
- * drivers/base/memory.c - basic Memory class support
+ * Memory subsystem support
  *
  * Written by Matt Tolentino <matthew.e.tolentino@intel.com>
  *            Dave Hansen <haveblue@us.ibm.com>
@@ -10,43 +10,42 @@
  * 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/topology.h>
 #include <linux/capability.h>
 #include <linux/device.h>
 #include <linux/memory.h>
-#include <linux/kobject.h>
 #include <linux/memory_hotplug.h>
 #include <linux/mm.h>
 #include <linux/mutex.h>
 #include <linux/stat.h>
+#include <linux/slab.h>
 
-#include <asm/atomic.h>
+#include <linux/atomic.h>
 #include <asm/uaccess.h>
 
+static DEFINE_MUTEX(mem_sysfs_mutex);
+
 #define MEMORY_CLASS_NAME	"memory"
 
-static struct sysdev_class memory_sysdev_class = {
-	.name = MEMORY_CLASS_NAME,
-};
+#define to_memory_block(dev) container_of(dev, struct memory_block, dev)
 
-static const char *memory_uevent_name(struct kset *kset, struct kobject *kobj)
-{
-	return MEMORY_CLASS_NAME;
-}
+static int sections_per_block;
 
-static int memory_uevent(struct kset *kset, struct kobject *obj, struct kobj_uevent_env *env)
+static inline int base_memory_block_id(int section_nr)
 {
-	int retval = 0;
-
-	return retval;
+	return section_nr / sections_per_block;
 }
 
-static struct kset_uevent_ops memory_uevent_ops = {
-	.name		= memory_uevent_name,
-	.uevent		= memory_uevent,
+static int memory_subsys_online(struct device *dev);
+static int memory_subsys_offline(struct device *dev);
+
+static struct bus_type memory_subsys = {
+	.name = MEMORY_CLASS_NAME,
+	.dev_name = MEMORY_CLASS_NAME,
+	.online = memory_subsys_online,
+	.offline = memory_subsys_offline,
 };
 
 static BLOCKING_NOTIFIER_HEAD(memory_chain);
@@ -77,30 +76,31 @@ void unregister_memory_isolate_notifier(struct notifier_block *nb)
 }
 EXPORT_SYMBOL(unregister_memory_isolate_notifier);
 
-/*
- * register_memory - Setup a sysfs device for a memory block
- */
-static
-int register_memory(struct memory_block *memory, struct mem_section *section)
+static void memory_block_release(struct device *dev)
 {
-	int error;
+	struct memory_block *mem = to_memory_block(dev);
 
-	memory->sysdev.cls = &memory_sysdev_class;
-	memory->sysdev.id = __section_nr(section);
+	kfree(mem);
+}
 
-	error = sysdev_register(&memory->sysdev);
-	return error;
+unsigned long __weak memory_block_size_bytes(void)
+{
+	return MIN_MEMORY_BLOCK_SIZE;
 }
 
-static void
-unregister_memory(struct memory_block *memory, struct mem_section *section)
+static unsigned long get_memory_block_size(void)
 {
-	BUG_ON(memory->sysdev.cls != &memory_sysdev_class);
-	BUG_ON(memory->sysdev.id != __section_nr(section));
+	unsigned long block_sz;
 
-	/* drop the ref. we got in remove_memory_block() */
-	kobject_put(&memory->sysdev.kobj);
-	sysdev_unregister(&memory->sysdev);
+	block_sz = memory_block_size_bytes();
+
+	/* Validate blk_sz is a power of 2 and not less than section size */
+	if ((block_sz & (block_sz - 1)) || (block_sz < MIN_MEMORY_BLOCK_SIZE)) {
+		WARN_ON(1);
+		block_sz = MIN_MEMORY_BLOCK_SIZE;
+	}
+
+	return block_sz;
 }
 
 /*
@@ -108,38 +108,43 @@ unregister_memory(struct memory_block *memory, struct mem_section *section)
  * uses.
  */
 
-static ssize_t show_mem_phys_index(struct sys_device *dev,
-			struct sysdev_attribute *attr, char *buf)
+static ssize_t show_mem_start_phys_index(struct device *dev,
+			struct device_attribute *attr, char *buf)
 {
-	struct memory_block *mem =
-		container_of(dev, struct memory_block, sysdev);
-	return sprintf(buf, "%08lx\n", mem->phys_index);
+	struct memory_block *mem = to_memory_block(dev);
+	unsigned long phys_index;
+
+	phys_index = mem->start_section_nr / sections_per_block;
+	return sprintf(buf, "%08lx\n", phys_index);
 }
 
 /*
  * Show whether the section of memory is likely to be hot-removable
  */
-static ssize_t show_mem_removable(struct sys_device *dev,
-			struct sysdev_attribute *attr, char *buf)
+static ssize_t show_mem_removable(struct device *dev,
+			struct device_attribute *attr, char *buf)
 {
-	unsigned long start_pfn;
-	int ret;
-	struct memory_block *mem =
-		container_of(dev, struct memory_block, sysdev);
+	unsigned long i, pfn;
+	int ret = 1;
+	struct memory_block *mem = to_memory_block(dev);
+
+	for (i = 0; i < sections_per_block; i++) {
+		if (!present_section_nr(mem->start_section_nr + i))
+			continue;
+		pfn = section_nr_to_pfn(mem->start_section_nr + i);
+		ret &= is_mem_section_removable(pfn, PAGES_PER_SECTION);
+	}
 
-	start_pfn = section_nr_to_pfn(mem->phys_index);
-	ret = is_mem_section_removable(start_pfn, PAGES_PER_SECTION);
 	return sprintf(buf, "%d\n", ret);
 }
 
 /*
  * online, offline, going offline, etc.
  */
-static ssize_t show_mem_state(struct sys_device *dev,
-			struct sysdev_attribute *attr, char *buf)
+static ssize_t show_mem_state(struct device *dev,
+			struct device_attribute *attr, char *buf)
 {
-	struct memory_block *mem =
-		container_of(dev, struct memory_block, sysdev);
+	struct memory_block *mem = to_memory_block(dev);
 	ssize_t len = 0;
 
 	/*
@@ -177,57 +182,68 @@ int memory_isolate_notify(unsigned long val, void *v)
 }
 
 /*
- * MEMORY_HOTPLUG depends on SPARSEMEM in mm/Kconfig, so it is
- * OK to have direct references to sparsemem variables in here.
+ * The probe routines leave the pages reserved, just as the bootmem code does.
+ * Make sure they're still that way.
  */
-static int
-memory_block_action(struct memory_block *mem, unsigned long action)
+static bool pages_correctly_reserved(unsigned long start_pfn)
 {
-	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);
+	int i, j;
+	struct page *page;
+	unsigned long pfn = start_pfn;
 
 	/*
-	 * The probe routines leave the pages reserved, just
-	 * as the bootmem code does.  Make sure they're still
-	 * that way.
+	 * memmap between sections is not contiguous except with
+	 * SPARSEMEM_VMEMMAP. We lookup the page once per section
+	 * and assume memmap is contiguous within each section
 	 */
-	if (action == MEM_ONLINE) {
-		for (i = 0; i < PAGES_PER_SECTION; i++) {
-			if (PageReserved(first_page+i))
+	for (i = 0; i < sections_per_block; i++, pfn += PAGES_PER_SECTION) {
+		if (WARN_ON_ONCE(!pfn_valid(pfn)))
+			return false;
+		page = pfn_to_page(pfn);
+
+		for (j = 0; j < PAGES_PER_SECTION; j++) {
+			if (PageReserved(page + j))
 				continue;
 
 			printk(KERN_WARNING "section number %ld page number %d "
-				"not reserved, was it already online? \n",
-				psection, i);
-			return -EBUSY;
+				"not reserved, was it already online?\n",
+				pfn_to_section_nr(pfn), j);
+
+			return false;
 		}
 	}
 
+	return true;
+}
+
+/*
+ * 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(unsigned long phys_index, unsigned long action, int online_type)
+{
+	unsigned long start_pfn;
+	unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block;
+	struct page *first_page;
+	int ret;
+
+	first_page = pfn_to_page(phys_index << PFN_SECTION_SHIFT);
+	start_pfn = page_to_pfn(first_page);
+
 	switch (action) {
 		case MEM_ONLINE:
-			start_pfn = page_to_pfn(first_page);
-			ret = online_pages(start_pfn, PAGES_PER_SECTION);
+			if (!pages_correctly_reserved(start_pfn))
+				return -EBUSY;
+
+			ret = online_pages(start_pfn, nr_pages, online_type);
 			break;
 		case MEM_OFFLINE:
-			mem->state = MEM_GOING_OFFLINE;
-			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;
-			}
+			ret = offline_pages(start_pfn, nr_pages);
 			break;
 		default:
-			WARN(1, KERN_WARNING "%s(%p, %ld) unknown action: %ld\n",
-					__func__, mem, action, action);
+			WARN(1, KERN_WARNING "%s(%ld, %ld) unknown action: "
+			     "%ld\n", __func__, phys_index, action, action);
 			ret = -EINVAL;
 	}
 
@@ -238,41 +254,104 @@ static int memory_block_change_state(struct memory_block *mem,
 		unsigned long to_state, unsigned long from_state_req)
 {
 	int ret = 0;
-	mutex_lock(&mem->state_mutex);
 
-	if (mem->state != from_state_req) {
-		ret = -EINVAL;
-		goto out;
-	}
+	if (mem->state != from_state_req)
+		return -EINVAL;
 
-	ret = memory_block_action(mem, to_state);
-	if (!ret)
-		mem->state = to_state;
+	if (to_state == MEM_OFFLINE)
+		mem->state = MEM_GOING_OFFLINE;
+
+	ret = memory_block_action(mem->start_section_nr, to_state,
+				mem->online_type);
+
+	mem->state = ret ? from_state_req : to_state;
 
-out:
-	mutex_unlock(&mem->state_mutex);
 	return ret;
 }
 
+/* The device lock serializes operations on memory_subsys_[online|offline] */
+static int memory_subsys_online(struct device *dev)
+{
+	struct memory_block *mem = to_memory_block(dev);
+	int ret;
+
+	if (mem->state == MEM_ONLINE)
+		return 0;
+
+	/*
+	 * If we are called from store_mem_state(), online_type will be
+	 * set >= 0 Otherwise we were called from the device online
+	 * attribute and need to set the online_type.
+	 */
+	if (mem->online_type < 0)
+		mem->online_type = ONLINE_KEEP;
+
+	ret = memory_block_change_state(mem, MEM_ONLINE, MEM_OFFLINE);
+
+	/* clear online_type */
+	mem->online_type = -1;
+
+	return ret;
+}
+
+static int memory_subsys_offline(struct device *dev)
+{
+	struct memory_block *mem = to_memory_block(dev);
+
+	if (mem->state == MEM_OFFLINE)
+		return 0;
+
+	return memory_block_change_state(mem, MEM_OFFLINE, MEM_ONLINE);
+}
+
 static ssize_t
-store_mem_state(struct sys_device *dev,
-		struct sysdev_attribute *attr, const char *buf, size_t count)
+store_mem_state(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t count)
 {
-	struct memory_block *mem;
-	unsigned int phys_section_nr;
-	int ret = -EINVAL;
+	struct memory_block *mem = to_memory_block(dev);
+	int ret, online_type;
 
-	mem = container_of(dev, struct memory_block, sysdev);
-	phys_section_nr = mem->phys_index;
+	ret = lock_device_hotplug_sysfs();
+	if (ret)
+		return ret;
 
-	if (!present_section_nr(phys_section_nr))
-		goto out;
+	if (!strncmp(buf, "online_kernel", min_t(int, count, 13)))
+		online_type = ONLINE_KERNEL;
+	else if (!strncmp(buf, "online_movable", min_t(int, count, 14)))
+		online_type = ONLINE_MOVABLE;
+	else if (!strncmp(buf, "online", min_t(int, count, 6)))
+		online_type = ONLINE_KEEP;
+	else if (!strncmp(buf, "offline", min_t(int, count, 7)))
+		online_type = -1;
+	else {
+		ret = -EINVAL;
+		goto err;
+	}
+
+	switch (online_type) {
+	case ONLINE_KERNEL:
+	case ONLINE_MOVABLE:
+	case ONLINE_KEEP:
+		/*
+		 * mem->online_type is not protected so there can be a
+		 * race here.  However, when racing online, the first
+		 * will succeed and the second will just return as the
+		 * block will already be online.  The online type
+		 * could be either one, but that is expected.
+		 */
+		mem->online_type = online_type;
+		ret = device_online(&mem->dev);
+		break;
+	case -1:
+		ret = device_offline(&mem->dev);
+		break;
+	default:
+		ret = -EINVAL; /* should never happen */
+	}
+
+err:
+	unlock_device_hotplug();
 
-	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;
@@ -287,40 +366,29 @@ out:
  * 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,
-				struct sysdev_attribute *attr, char *buf)
+static ssize_t show_phys_device(struct device *dev,
+				struct device_attribute *attr, char *buf)
 {
-	struct memory_block *mem =
-		container_of(dev, struct memory_block, sysdev);
+	struct memory_block *mem = to_memory_block(dev);
 	return sprintf(buf, "%d\n", mem->phys_device);
 }
 
-static SYSDEV_ATTR(phys_index, 0444, show_mem_phys_index, NULL);
-static SYSDEV_ATTR(state, 0644, show_mem_state, store_mem_state);
-static SYSDEV_ATTR(phys_device, 0444, show_phys_device, NULL);
-static SYSDEV_ATTR(removable, 0444, show_mem_removable, 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)
+static DEVICE_ATTR(phys_index, 0444, show_mem_start_phys_index, NULL);
+static DEVICE_ATTR(state, 0644, show_mem_state, store_mem_state);
+static DEVICE_ATTR(phys_device, 0444, show_phys_device, NULL);
+static DEVICE_ATTR(removable, 0444, show_mem_removable, NULL);
 
 /*
  * Block size attribute stuff
  */
 static ssize_t
-print_block_size(struct class *class, char *buf)
+print_block_size(struct device *dev, struct device_attribute *attr,
+		 char *buf)
 {
-	return sprintf(buf, "%lx\n", (unsigned long)PAGES_PER_SECTION * PAGE_SIZE);
+	return sprintf(buf, "%lx\n", get_memory_block_size());
 }
 
-static CLASS_ATTR(block_size_bytes, 0444, print_block_size, NULL);
-
-static int block_size_init(void)
-{
-	return sysfs_create_file(&memory_sysdev_class.kset.kobj,
-				&class_attr_block_size_bytes.attr);
-}
+static DEVICE_ATTR(block_size_bytes, 0444, print_block_size, NULL);
 
 /*
  * Some architectures will have custom drivers to do this, and
@@ -330,34 +398,35 @@ static int block_size_init(void)
  */
 #ifdef CONFIG_ARCH_MEMORY_PROBE
 static ssize_t
-memory_probe_store(struct class *class, const char *buf, size_t count)
+memory_probe_store(struct device *dev, struct device_attribute *attr,
+		   const char *buf, size_t count)
 {
 	u64 phys_addr;
 	int nid;
-	int ret;
+	int i, ret;
+	unsigned long pages_per_block = PAGES_PER_SECTION * sections_per_block;
 
 	phys_addr = simple_strtoull(buf, NULL, 0);
 
-	nid = memory_add_physaddr_to_nid(phys_addr);
-	ret = add_memory(nid, phys_addr, PAGES_PER_SECTION << PAGE_SHIFT);
+	if (phys_addr & ((pages_per_block << PAGE_SHIFT) - 1))
+		return -EINVAL;
 
-	if (ret)
-		count = ret;
+	for (i = 0; i < sections_per_block; i++) {
+		nid = memory_add_physaddr_to_nid(phys_addr);
+		ret = add_memory(nid, phys_addr,
+				 PAGES_PER_SECTION << PAGE_SHIFT);
+		if (ret)
+			goto out;
 
-	return count;
-}
-static CLASS_ATTR(probe, S_IWUSR, NULL, memory_probe_store);
+		phys_addr += MIN_MEMORY_BLOCK_SIZE;
+	}
 
-static int memory_probe_init(void)
-{
-	return sysfs_create_file(&memory_sysdev_class.kset.kobj,
-				&class_attr_probe.attr);
-}
-#else
-static inline int memory_probe_init(void)
-{
-	return 0;
+	ret = count;
+out:
+	return ret;
 }
+
+static DEVICE_ATTR(probe, S_IWUSR, NULL, memory_probe_store);
 #endif
 
 #ifdef CONFIG_MEMORY_FAILURE
@@ -367,13 +436,15 @@ static inline int memory_probe_init(void)
 
 /* Soft offline a page */
 static ssize_t
-store_soft_offline_page(struct class *class, const char *buf, size_t count)
+store_soft_offline_page(struct device *dev,
+			struct device_attribute *attr,
+			const char *buf, size_t count)
 {
 	int ret;
 	u64 pfn;
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
-	if (strict_strtoull(buf, 0, &pfn) < 0)
+	if (kstrtoull(buf, 0, &pfn) < 0)
 		return -EINVAL;
 	pfn >>= PAGE_SHIFT;
 	if (!pfn_valid(pfn))
@@ -384,38 +455,23 @@ store_soft_offline_page(struct class *class, const char *buf, size_t count)
 
 /* Forcibly offline a page, including killing processes. */
 static ssize_t
-store_hard_offline_page(struct class *class, const char *buf, size_t count)
+store_hard_offline_page(struct device *dev,
+			struct device_attribute *attr,
+			const char *buf, size_t count)
 {
 	int ret;
 	u64 pfn;
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
-	if (strict_strtoull(buf, 0, &pfn) < 0)
+	if (kstrtoull(buf, 0, &pfn) < 0)
 		return -EINVAL;
 	pfn >>= PAGE_SHIFT;
-	ret = __memory_failure(pfn, 0, 0);
+	ret = memory_failure(pfn, 0, 0);
 	return ret ? ret : count;
 }
 
-static CLASS_ATTR(soft_offline_page, 0644, NULL, store_soft_offline_page);
-static CLASS_ATTR(hard_offline_page, 0644, NULL, store_hard_offline_page);
-
-static __init int memory_fail_init(void)
-{
-	int err;
-
-	err = sysfs_create_file(&memory_sysdev_class.kset.kobj,
-				&class_attr_soft_offline_page.attr);
-	if (!err)
-		err = sysfs_create_file(&memory_sysdev_class.kset.kobj,
-				&class_attr_hard_offline_page.attr);
-	return err;
-}
-#else
-static inline int memory_fail_init(void)
-{
-	return 0;
-}
+static DEVICE_ATTR(soft_offline_page, S_IWUSR, NULL, store_soft_offline_page);
+static DEVICE_ATTR(hard_offline_page, S_IWUSR, NULL, store_hard_offline_page);
 #endif
 
 /*
@@ -423,37 +479,28 @@ static inline int memory_fail_init(void)
  * differentiation between which *physical* devices each
  * section belongs to...
  */
-
-static int add_memory_block(int nid, struct mem_section *section,
-			unsigned long state, int phys_device,
-			enum mem_add_context context)
+int __weak arch_get_memory_phys_device(unsigned long start_pfn)
 {
-	struct memory_block *mem = kzalloc(sizeof(*mem), GFP_KERNEL);
-	int ret = 0;
-
-	if (!mem)
-		return -ENOMEM;
+	return 0;
+}
 
-	mem->phys_index = __section_nr(section);
-	mem->state = state;
-	mutex_init(&mem->state_mutex);
-	mem->phys_device = phys_device;
-
-	ret = register_memory(mem, section);
-	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);
-	if (!ret)
-		ret = mem_create_simple_file(mem, removable);
-	if (!ret) {
-		if (context == HOTPLUG)
-			ret = register_mem_sect_under_node(mem, nid);
-	}
+/*
+ * A reference for the returned object is held and the reference for the
+ * hinted object is released.
+ */
+struct memory_block *find_memory_block_hinted(struct mem_section *section,
+					      struct memory_block *hint)
+{
+	int block_id = base_memory_block_id(__section_nr(section));
+	struct device *hintdev = hint ? &hint->dev : NULL;
+	struct device *dev;
 
-	return ret;
+	dev = subsys_find_device_by_id(&memory_subsys, block_id, hintdev);
+	if (hint)
+		put_device(&hint->dev);
+	if (!dev)
+		return NULL;
+	return to_memory_block(dev);
 }
 
 /*
@@ -462,54 +509,153 @@ static int add_memory_block(int nid, struct mem_section *section,
  * 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.
+ * This could be made generic for all device subsystems.
  */
 struct memory_block *find_memory_block(struct mem_section *section)
 {
-	struct kobject *kobj;
-	struct sys_device *sysdev;
+	return find_memory_block_hinted(section, NULL);
+}
+
+static struct attribute *memory_memblk_attrs[] = {
+	&dev_attr_phys_index.attr,
+	&dev_attr_state.attr,
+	&dev_attr_phys_device.attr,
+	&dev_attr_removable.attr,
+	NULL
+};
+
+static struct attribute_group memory_memblk_attr_group = {
+	.attrs = memory_memblk_attrs,
+};
+
+static const struct attribute_group *memory_memblk_attr_groups[] = {
+	&memory_memblk_attr_group,
+	NULL,
+};
+
+/*
+ * register_memory - Setup a sysfs device for a memory block
+ */
+static
+int register_memory(struct memory_block *memory)
+{
+	memory->dev.bus = &memory_subsys;
+	memory->dev.id = memory->start_section_nr / sections_per_block;
+	memory->dev.release = memory_block_release;
+	memory->dev.groups = memory_memblk_attr_groups;
+	memory->dev.offline = memory->state == MEM_OFFLINE;
+
+	return device_register(&memory->dev);
+}
+
+static int init_memory_block(struct memory_block **memory,
+			     struct mem_section *section, unsigned long state)
+{
 	struct memory_block *mem;
-	char name[sizeof(MEMORY_CLASS_NAME) + 9 + 1];
+	unsigned long start_pfn;
+	int scn_nr;
+	int ret = 0;
 
-	/*
-	 * 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));
+	mem = kzalloc(sizeof(*mem), GFP_KERNEL);
+	if (!mem)
+		return -ENOMEM;
 
-	kobj = kset_find_obj(&memory_sysdev_class.kset, name);
-	if (!kobj)
-		return NULL;
+	scn_nr = __section_nr(section);
+	mem->start_section_nr =
+			base_memory_block_id(scn_nr) * sections_per_block;
+	mem->end_section_nr = mem->start_section_nr + sections_per_block - 1;
+	mem->state = state;
+	mem->section_count++;
+	start_pfn = section_nr_to_pfn(mem->start_section_nr);
+	mem->phys_device = arch_get_memory_phys_device(start_pfn);
 
-	sysdev = container_of(kobj, struct sys_device, kobj);
-	mem = container_of(sysdev, struct memory_block, sysdev);
+	ret = register_memory(mem);
 
-	return mem;
+	*memory = mem;
+	return ret;
 }
 
-int remove_memory_block(unsigned long node_id, struct mem_section *section,
-		int phys_device)
+static int add_memory_block(int base_section_nr)
 {
 	struct memory_block *mem;
+	int i, ret, section_count = 0, section_nr;
 
-	mem = find_memory_block(section);
-	unregister_mem_sect_under_nodes(mem);
-	mem_remove_simple_file(mem, phys_index);
-	mem_remove_simple_file(mem, state);
-	mem_remove_simple_file(mem, phys_device);
-	mem_remove_simple_file(mem, removable);
-	unregister_memory(mem, section);
+	for (i = base_section_nr;
+	     (i < base_section_nr + sections_per_block) && i < NR_MEM_SECTIONS;
+	     i++) {
+		if (!present_section_nr(i))
+			continue;
+		if (section_count == 0)
+			section_nr = i;
+		section_count++;
+	}
 
+	if (section_count == 0)
+		return 0;
+	ret = init_memory_block(&mem, __nr_to_section(section_nr), MEM_ONLINE);
+	if (ret)
+		return ret;
+	mem->section_count = section_count;
 	return 0;
 }
 
+
 /*
  * need an interface for the VM to add new memory regions,
  * but without onlining it.
  */
 int register_new_memory(int nid, struct mem_section *section)
 {
-	return add_memory_block(nid, section, MEM_OFFLINE, 0, HOTPLUG);
+	int ret = 0;
+	struct memory_block *mem;
+
+	mutex_lock(&mem_sysfs_mutex);
+
+	mem = find_memory_block(section);
+	if (mem) {
+		mem->section_count++;
+		put_device(&mem->dev);
+	} else {
+		ret = init_memory_block(&mem, section, MEM_OFFLINE);
+		if (ret)
+			goto out;
+	}
+
+	if (mem->section_count == sections_per_block)
+		ret = register_mem_sect_under_node(mem, nid);
+out:
+	mutex_unlock(&mem_sysfs_mutex);
+	return ret;
+}
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+static void
+unregister_memory(struct memory_block *memory)
+{
+	BUG_ON(memory->dev.bus != &memory_subsys);
+
+	/* drop the ref. we got in remove_memory_block() */
+	put_device(&memory->dev);
+	device_unregister(&memory->dev);
+}
+
+static int remove_memory_block(unsigned long node_id,
+			       struct mem_section *section, int phys_device)
+{
+	struct memory_block *mem;
+
+	mutex_lock(&mem_sysfs_mutex);
+	mem = find_memory_block(section);
+	unregister_mem_sect_under_nodes(mem, __section_nr(section));
+
+	mem->section_count--;
+	if (mem->section_count == 0)
+		unregister_memory(mem);
+	else
+		put_device(&mem->dev);
+
+	mutex_unlock(&mem_sysfs_mutex);
+	return 0;
 }
 
 int unregister_memory_section(struct mem_section *section)
@@ -519,6 +665,36 @@ int unregister_memory_section(struct mem_section *section)
 
 	return remove_memory_block(0, section, 0);
 }
+#endif /* CONFIG_MEMORY_HOTREMOVE */
+
+/* return true if the memory block is offlined, otherwise, return false */
+bool is_memblock_offlined(struct memory_block *mem)
+{
+	return mem->state == MEM_OFFLINE;
+}
+
+static struct attribute *memory_root_attrs[] = {
+#ifdef CONFIG_ARCH_MEMORY_PROBE
+	&dev_attr_probe.attr,
+#endif
+
+#ifdef CONFIG_MEMORY_FAILURE
+	&dev_attr_soft_offline_page.attr,
+	&dev_attr_hard_offline_page.attr,
+#endif
+
+	&dev_attr_block_size_bytes.attr,
+	NULL
+};
+
+static struct attribute_group memory_root_attr_group = {
+	.attrs = memory_root_attrs,
+};
+
+static const struct attribute_group *memory_root_attr_groups[] = {
+	&memory_root_attr_group,
+	NULL,
+};
 
 /*
  * Initialize the sysfs support for memory devices...
@@ -528,34 +704,27 @@ int __init memory_dev_init(void)
 	unsigned int i;
 	int ret;
 	int err;
+	unsigned long block_sz;
 
-	memory_sysdev_class.kset.uevent_ops = &memory_uevent_ops;
-	ret = sysdev_class_register(&memory_sysdev_class);
+	ret = subsys_system_register(&memory_subsys, memory_root_attr_groups);
 	if (ret)
 		goto out;
 
+	block_sz = get_memory_block_size();
+	sections_per_block = block_sz / MIN_MEMORY_BLOCK_SIZE;
+
 	/*
 	 * Create entries for memory sections that were found
 	 * during boot and have been initialized
 	 */
-	for (i = 0; i < NR_MEM_SECTIONS; i++) {
-		if (!present_section_nr(i))
-			continue;
-		err = add_memory_block(0, __nr_to_section(i), MEM_ONLINE,
-					0, BOOT);
+	mutex_lock(&mem_sysfs_mutex);
+	for (i = 0; i < NR_MEM_SECTIONS; i += sections_per_block) {
+		err = add_memory_block(i);
 		if (!ret)
 			ret = err;
 	}
+	mutex_unlock(&mem_sysfs_mutex);
 
-	err = memory_probe_init();
-	if (!ret)
-		ret = err;
-	err = memory_fail_init();
-	if (!ret)
-		ret = err;
-	err = block_size_init();
-	if (!ret)
-		ret = err;
 out:
 	if (ret)
 		printk(KERN_ERR "%s() failed: %d\n", __func__, ret);