diff --git a/drivers/Kconfig b/drivers/Kconfig
index 3a0e354..80f0ec9 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -97,4 +97,6 @@
 source "drivers/auxdisplay/Kconfig"
 
 source "drivers/uio/Kconfig"
+
+source "drivers/xen/Kconfig"
 endmenu
diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
new file mode 100644
index 0000000..4b75a16
--- /dev/null
+++ b/drivers/xen/Kconfig
@@ -0,0 +1,19 @@
+config XEN_BALLOON
+	bool "Xen memory balloon driver"
+	depends on XEN
+	default y
+	help
+	  The balloon driver allows the Xen domain to request more memory from
+	  the system to expand the domain's memory allocation, or alternatively
+	  return unneeded memory to the system.
+
+config XEN_SCRUB_PAGES
+	bool "Scrub pages before returning them to system"
+	depends on XEN_BALLOON
+	default y
+	help
+	  Scrub pages before returning them to the system for reuse by
+	  other domains.  This makes sure that any confidential data
+	  is not accidentally visible to other domains.  Is it more
+	  secure, but slightly less efficient.
+	  If in doubt, say yes.
diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index 43f014c..37af04f 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -1,3 +1,4 @@
 obj-y	+= grant-table.o features.o events.o
 obj-y	+= xenbus/
 obj-$(CONFIG_XEN_XENCOMM)	+= xencomm.o
+obj-$(CONFIG_XEN_BALLOON)	+= balloon.o
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
new file mode 100644
index 0000000..ab25ba6
--- /dev/null
+++ b/drivers/xen/balloon.c
@@ -0,0 +1,712 @@
+/******************************************************************************
+ * balloon.c
+ *
+ * Xen balloon driver - enables returning/claiming memory to/from Xen.
+ *
+ * Copyright (c) 2003, B Dragovic
+ * Copyright (c) 2003-2004, M Williamson, K Fraser
+ * Copyright (c) 2005 Dan M. Smith, IBM Corporation
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/errno.h>
+#include <linux/mm.h>
+#include <linux/bootmem.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/mutex.h>
+#include <linux/highmem.h>
+#include <linux/list.h>
+#include <linux/sysdev.h>
+
+#include <asm/xen/hypervisor.h>
+#include <asm/page.h>
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+#include <asm/uaccess.h>
+#include <asm/tlb.h>
+
+#include <xen/interface/memory.h>
+#include <xen/balloon.h>
+#include <xen/xenbus.h>
+#include <xen/features.h>
+#include <xen/page.h>
+
+#define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10))
+
+#define BALLOON_CLASS_NAME "memory"
+
+struct balloon_stats {
+	/* We aim for 'current allocation' == 'target allocation'. */
+	unsigned long current_pages;
+	unsigned long target_pages;
+	/* We may hit the hard limit in Xen. If we do then we remember it. */
+	unsigned long hard_limit;
+	/*
+	 * Drivers may alter the memory reservation independently, but they
+	 * must inform the balloon driver so we avoid hitting the hard limit.
+	 */
+	unsigned long driver_pages;
+	/* Number of pages in high- and low-memory balloons. */
+	unsigned long balloon_low;
+	unsigned long balloon_high;
+};
+
+static DEFINE_MUTEX(balloon_mutex);
+
+static struct sys_device balloon_sysdev;
+
+static int register_balloon(struct sys_device *sysdev);
+
+/*
+ * Protects atomic reservation decrease/increase against concurrent increases.
+ * Also protects non-atomic updates of current_pages and driver_pages, and
+ * balloon lists.
+ */
+static DEFINE_SPINLOCK(balloon_lock);
+
+static struct balloon_stats balloon_stats;
+
+/* We increase/decrease in batches which fit in a page */
+static unsigned long frame_list[PAGE_SIZE / sizeof(unsigned long)];
+
+/* VM /proc information for memory */
+extern unsigned long totalram_pages;
+
+#ifdef CONFIG_HIGHMEM
+extern unsigned long totalhigh_pages;
+#define inc_totalhigh_pages() (totalhigh_pages++)
+#define dec_totalhigh_pages() (totalhigh_pages--)
+#else
+#define inc_totalhigh_pages() do {} while(0)
+#define dec_totalhigh_pages() do {} while(0)
+#endif
+
+/* List of ballooned pages, threaded through the mem_map array. */
+static LIST_HEAD(ballooned_pages);
+
+/* Main work function, always executed in process context. */
+static void balloon_process(struct work_struct *work);
+static DECLARE_WORK(balloon_worker, balloon_process);
+static struct timer_list balloon_timer;
+
+/* When ballooning out (allocating memory to return to Xen) we don't really
+   want the kernel to try too hard since that can trigger the oom killer. */
+#define GFP_BALLOON \
+	(GFP_HIGHUSER | __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC)
+
+static void scrub_page(struct page *page)
+{
+#ifdef CONFIG_XEN_SCRUB_PAGES
+	if (PageHighMem(page)) {
+		void *v = kmap(page);
+		clear_page(v);
+		kunmap(v);
+	} else {
+		void *v = page_address(page);
+		clear_page(v);
+	}
+#endif
+}
+
+/* balloon_append: add the given page to the balloon. */
+static void balloon_append(struct page *page)
+{
+	/* Lowmem is re-populated first, so highmem pages go at list tail. */
+	if (PageHighMem(page)) {
+		list_add_tail(&page->lru, &ballooned_pages);
+		balloon_stats.balloon_high++;
+		dec_totalhigh_pages();
+	} else {
+		list_add(&page->lru, &ballooned_pages);
+		balloon_stats.balloon_low++;
+	}
+}
+
+/* balloon_retrieve: rescue a page from the balloon, if it is not empty. */
+static struct page *balloon_retrieve(void)
+{
+	struct page *page;
+
+	if (list_empty(&ballooned_pages))
+		return NULL;
+
+	page = list_entry(ballooned_pages.next, struct page, lru);
+	list_del(&page->lru);
+
+	if (PageHighMem(page)) {
+		balloon_stats.balloon_high--;
+		inc_totalhigh_pages();
+	}
+	else
+		balloon_stats.balloon_low--;
+
+	return page;
+}
+
+static struct page *balloon_first_page(void)
+{
+	if (list_empty(&ballooned_pages))
+		return NULL;
+	return list_entry(ballooned_pages.next, struct page, lru);
+}
+
+static struct page *balloon_next_page(struct page *page)
+{
+	struct list_head *next = page->lru.next;
+	if (next == &ballooned_pages)
+		return NULL;
+	return list_entry(next, struct page, lru);
+}
+
+static void balloon_alarm(unsigned long unused)
+{
+	schedule_work(&balloon_worker);
+}
+
+static unsigned long current_target(void)
+{
+	unsigned long target = min(balloon_stats.target_pages, balloon_stats.hard_limit);
+
+	target = min(target,
+		     balloon_stats.current_pages +
+		     balloon_stats.balloon_low +
+		     balloon_stats.balloon_high);
+
+	return target;
+}
+
+static int increase_reservation(unsigned long nr_pages)
+{
+	unsigned long  pfn, i, flags;
+	struct page   *page;
+	long           rc;
+	struct xen_memory_reservation reservation = {
+		.address_bits = 0,
+		.extent_order = 0,
+		.domid        = DOMID_SELF
+	};
+
+	if (nr_pages > ARRAY_SIZE(frame_list))
+		nr_pages = ARRAY_SIZE(frame_list);
+
+	spin_lock_irqsave(&balloon_lock, flags);
+
+	page = balloon_first_page();
+	for (i = 0; i < nr_pages; i++) {
+		BUG_ON(page == NULL);
+		frame_list[i] = page_to_pfn(page);;
+		page = balloon_next_page(page);
+	}
+
+	reservation.extent_start = (unsigned long)frame_list;
+	reservation.nr_extents   = nr_pages;
+	rc = HYPERVISOR_memory_op(
+		XENMEM_populate_physmap, &reservation);
+	if (rc < nr_pages) {
+		if (rc > 0) {
+			int ret;
+
+			/* We hit the Xen hard limit: reprobe. */
+			reservation.nr_extents = rc;
+			ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation,
+					&reservation);
+			BUG_ON(ret != rc);
+		}
+		if (rc >= 0)
+			balloon_stats.hard_limit = (balloon_stats.current_pages + rc -
+						    balloon_stats.driver_pages);
+		goto out;
+	}
+
+	for (i = 0; i < nr_pages; i++) {
+		page = balloon_retrieve();
+		BUG_ON(page == NULL);
+
+		pfn = page_to_pfn(page);
+		BUG_ON(!xen_feature(XENFEAT_auto_translated_physmap) &&
+		       phys_to_machine_mapping_valid(pfn));
+
+		set_phys_to_machine(pfn, frame_list[i]);
+
+		/* Link back into the page tables if not highmem. */
+		if (pfn < max_low_pfn) {
+			int ret;
+			ret = HYPERVISOR_update_va_mapping(
+				(unsigned long)__va(pfn << PAGE_SHIFT),
+				mfn_pte(frame_list[i], PAGE_KERNEL),
+				0);
+			BUG_ON(ret);
+		}
+
+		/* Relinquish the page back to the allocator. */
+		ClearPageReserved(page);
+		init_page_count(page);
+		__free_page(page);
+	}
+
+	balloon_stats.current_pages += nr_pages;
+	totalram_pages = balloon_stats.current_pages;
+
+ out:
+	spin_unlock_irqrestore(&balloon_lock, flags);
+
+	return 0;
+}
+
+static int decrease_reservation(unsigned long nr_pages)
+{
+	unsigned long  pfn, i, flags;
+	struct page   *page;
+	int            need_sleep = 0;
+	int ret;
+	struct xen_memory_reservation reservation = {
+		.address_bits = 0,
+		.extent_order = 0,
+		.domid        = DOMID_SELF
+	};
+
+	if (nr_pages > ARRAY_SIZE(frame_list))
+		nr_pages = ARRAY_SIZE(frame_list);
+
+	for (i = 0; i < nr_pages; i++) {
+		if ((page = alloc_page(GFP_BALLOON)) == NULL) {
+			nr_pages = i;
+			need_sleep = 1;
+			break;
+		}
+
+		pfn = page_to_pfn(page);
+		frame_list[i] = pfn_to_mfn(pfn);
+
+		scrub_page(page);
+	}
+
+	/* Ensure that ballooned highmem pages don't have kmaps. */
+	kmap_flush_unused();
+	flush_tlb_all();
+
+	spin_lock_irqsave(&balloon_lock, flags);
+
+	/* No more mappings: invalidate P2M and add to balloon. */
+	for (i = 0; i < nr_pages; i++) {
+		pfn = mfn_to_pfn(frame_list[i]);
+		set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
+		balloon_append(pfn_to_page(pfn));
+	}
+
+	reservation.extent_start = (unsigned long)frame_list;
+	reservation.nr_extents   = nr_pages;
+	ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);
+	BUG_ON(ret != nr_pages);
+
+	balloon_stats.current_pages -= nr_pages;
+	totalram_pages = balloon_stats.current_pages;
+
+	spin_unlock_irqrestore(&balloon_lock, flags);
+
+	return need_sleep;
+}
+
+/*
+ * We avoid multiple worker processes conflicting via the balloon mutex.
+ * We may of course race updates of the target counts (which are protected
+ * by the balloon lock), or with changes to the Xen hard limit, but we will
+ * recover from these in time.
+ */
+static void balloon_process(struct work_struct *work)
+{
+	int need_sleep = 0;
+	long credit;
+
+	mutex_lock(&balloon_mutex);
+
+	do {
+		credit = current_target() - balloon_stats.current_pages;
+		if (credit > 0)
+			need_sleep = (increase_reservation(credit) != 0);
+		if (credit < 0)
+			need_sleep = (decrease_reservation(-credit) != 0);
+
+#ifndef CONFIG_PREEMPT
+		if (need_resched())
+			schedule();
+#endif
+	} while ((credit != 0) && !need_sleep);
+
+	/* Schedule more work if there is some still to be done. */
+	if (current_target() != balloon_stats.current_pages)
+		mod_timer(&balloon_timer, jiffies + HZ);
+
+	mutex_unlock(&balloon_mutex);
+}
+
+/* Resets the Xen limit, sets new target, and kicks off processing. */
+void balloon_set_new_target(unsigned long target)
+{
+	/* No need for lock. Not read-modify-write updates. */
+	balloon_stats.hard_limit   = ~0UL;
+	balloon_stats.target_pages = target;
+	schedule_work(&balloon_worker);
+}
+
+static struct xenbus_watch target_watch =
+{
+	.node = "memory/target"
+};
+
+/* React to a change in the target key */
+static void watch_target(struct xenbus_watch *watch,
+			 const char **vec, unsigned int len)
+{
+	unsigned long long new_target;
+	int err;
+
+	err = xenbus_scanf(XBT_NIL, "memory", "target", "%llu", &new_target);
+	if (err != 1) {
+		/* This is ok (for domain0 at least) - so just return */
+		return;
+	}
+
+	/* The given memory/target value is in KiB, so it needs converting to
+	 * pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10.
+	 */
+	balloon_set_new_target(new_target >> (PAGE_SHIFT - 10));
+}
+
+static int balloon_init_watcher(struct notifier_block *notifier,
+				unsigned long event,
+				void *data)
+{
+	int err;
+
+	err = register_xenbus_watch(&target_watch);
+	if (err)
+		printk(KERN_ERR "Failed to set balloon watcher\n");
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block xenstore_notifier;
+
+static int __init balloon_init(void)
+{
+	unsigned long pfn;
+	struct page *page;
+
+	if (!is_running_on_xen())
+		return -ENODEV;
+
+	pr_info("xen_balloon: Initialising balloon driver.\n");
+
+	balloon_stats.current_pages = min(xen_start_info->nr_pages, max_pfn);
+	totalram_pages   = balloon_stats.current_pages;
+	balloon_stats.target_pages  = balloon_stats.current_pages;
+	balloon_stats.balloon_low   = 0;
+	balloon_stats.balloon_high  = 0;
+	balloon_stats.driver_pages  = 0UL;
+	balloon_stats.hard_limit    = ~0UL;
+
+	init_timer(&balloon_timer);
+	balloon_timer.data = 0;
+	balloon_timer.function = balloon_alarm;
+
+	register_balloon(&balloon_sysdev);
+
+	/* Initialise the balloon with excess memory space. */
+	for (pfn = xen_start_info->nr_pages; pfn < max_pfn; pfn++) {
+		page = pfn_to_page(pfn);
+		if (!PageReserved(page))
+			balloon_append(page);
+	}
+
+	target_watch.callback = watch_target;
+	xenstore_notifier.notifier_call = balloon_init_watcher;
+
+	register_xenstore_notifier(&xenstore_notifier);
+
+	return 0;
+}
+
+subsys_initcall(balloon_init);
+
+static void balloon_exit(void)
+{
+    /* XXX - release balloon here */
+    return;
+}
+
+module_exit(balloon_exit);
+
+static void balloon_update_driver_allowance(long delta)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&balloon_lock, flags);
+	balloon_stats.driver_pages += delta;
+	spin_unlock_irqrestore(&balloon_lock, flags);
+}
+
+static int dealloc_pte_fn(
+	pte_t *pte, struct page *pmd_page, unsigned long addr, void *data)
+{
+	unsigned long mfn = pte_mfn(*pte);
+	int ret;
+	struct xen_memory_reservation reservation = {
+		.nr_extents   = 1,
+		.extent_order = 0,
+		.domid        = DOMID_SELF
+	};
+	reservation.extent_start = (unsigned long)&mfn;
+	set_pte_at(&init_mm, addr, pte, __pte_ma(0ull));
+	set_phys_to_machine(__pa(addr) >> PAGE_SHIFT, INVALID_P2M_ENTRY);
+	ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);
+	BUG_ON(ret != 1);
+	return 0;
+}
+
+static struct page **alloc_empty_pages_and_pagevec(int nr_pages)
+{
+	unsigned long vaddr, flags;
+	struct page *page, **pagevec;
+	int i, ret;
+
+	pagevec = kmalloc(sizeof(page) * nr_pages, GFP_KERNEL);
+	if (pagevec == NULL)
+		return NULL;
+
+	for (i = 0; i < nr_pages; i++) {
+		page = pagevec[i] = alloc_page(GFP_KERNEL);
+		if (page == NULL)
+			goto err;
+
+		vaddr = (unsigned long)page_address(page);
+
+		scrub_page(page);
+
+		spin_lock_irqsave(&balloon_lock, flags);
+
+		if (xen_feature(XENFEAT_auto_translated_physmap)) {
+			unsigned long gmfn = page_to_pfn(page);
+			struct xen_memory_reservation reservation = {
+				.nr_extents   = 1,
+				.extent_order = 0,
+				.domid        = DOMID_SELF
+			};
+			reservation.extent_start = (unsigned long)&gmfn;
+			ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation,
+						   &reservation);
+			if (ret == 1)
+				ret = 0; /* success */
+		} else {
+			ret = apply_to_page_range(&init_mm, vaddr, PAGE_SIZE,
+						  dealloc_pte_fn, NULL);
+		}
+
+		if (ret != 0) {
+			spin_unlock_irqrestore(&balloon_lock, flags);
+			__free_page(page);
+			goto err;
+		}
+
+		totalram_pages = --balloon_stats.current_pages;
+
+		spin_unlock_irqrestore(&balloon_lock, flags);
+	}
+
+ out:
+	schedule_work(&balloon_worker);
+	flush_tlb_all();
+	return pagevec;
+
+ err:
+	spin_lock_irqsave(&balloon_lock, flags);
+	while (--i >= 0)
+		balloon_append(pagevec[i]);
+	spin_unlock_irqrestore(&balloon_lock, flags);
+	kfree(pagevec);
+	pagevec = NULL;
+	goto out;
+}
+
+static void free_empty_pages_and_pagevec(struct page **pagevec, int nr_pages)
+{
+	unsigned long flags;
+	int i;
+
+	if (pagevec == NULL)
+		return;
+
+	spin_lock_irqsave(&balloon_lock, flags);
+	for (i = 0; i < nr_pages; i++) {
+		BUG_ON(page_count(pagevec[i]) != 1);
+		balloon_append(pagevec[i]);
+	}
+	spin_unlock_irqrestore(&balloon_lock, flags);
+
+	kfree(pagevec);
+
+	schedule_work(&balloon_worker);
+}
+
+static void balloon_release_driver_page(struct page *page)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&balloon_lock, flags);
+	balloon_append(page);
+	balloon_stats.driver_pages--;
+	spin_unlock_irqrestore(&balloon_lock, flags);
+
+	schedule_work(&balloon_worker);
+}
+
+
+#define BALLOON_SHOW(name, format, args...)			\
+	static ssize_t show_##name(struct sys_device *dev,	\
+				   char *buf)			\
+	{							\
+		return sprintf(buf, format, ##args);		\
+	}							\
+	static SYSDEV_ATTR(name, S_IRUGO, show_##name, NULL)
+
+BALLOON_SHOW(current_kb, "%lu\n", PAGES2KB(balloon_stats.current_pages));
+BALLOON_SHOW(low_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_low));
+BALLOON_SHOW(high_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_high));
+BALLOON_SHOW(hard_limit_kb,
+	     (balloon_stats.hard_limit!=~0UL) ? "%lu\n" : "???\n",
+	     (balloon_stats.hard_limit!=~0UL) ? PAGES2KB(balloon_stats.hard_limit) : 0);
+BALLOON_SHOW(driver_kb, "%lu\n", PAGES2KB(balloon_stats.driver_pages));
+
+static ssize_t show_target_kb(struct sys_device *dev, char *buf)
+{
+	return sprintf(buf, "%lu\n", PAGES2KB(balloon_stats.target_pages));
+}
+
+static ssize_t store_target_kb(struct sys_device *dev,
+			       const char *buf,
+			       size_t count)
+{
+	char memstring[64], *endchar;
+	unsigned long long target_bytes;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	if (count <= 1)
+		return -EBADMSG; /* runt */
+	if (count > sizeof(memstring))
+		return -EFBIG;   /* too long */
+	strcpy(memstring, buf);
+
+	target_bytes = memparse(memstring, &endchar);
+	balloon_set_new_target(target_bytes >> PAGE_SHIFT);
+
+	return count;
+}
+
+static SYSDEV_ATTR(target_kb, S_IRUGO | S_IWUSR,
+		   show_target_kb, store_target_kb);
+
+static struct sysdev_attribute *balloon_attrs[] = {
+	&attr_target_kb,
+};
+
+static struct attribute *balloon_info_attrs[] = {
+	&attr_current_kb.attr,
+	&attr_low_kb.attr,
+	&attr_high_kb.attr,
+	&attr_hard_limit_kb.attr,
+	&attr_driver_kb.attr,
+	NULL
+};
+
+static struct attribute_group balloon_info_group = {
+	.name = "info",
+	.attrs = balloon_info_attrs,
+};
+
+static struct sysdev_class balloon_sysdev_class = {
+	.name = BALLOON_CLASS_NAME,
+};
+
+static int register_balloon(struct sys_device *sysdev)
+{
+	int i, error;
+
+	error = sysdev_class_register(&balloon_sysdev_class);
+	if (error)
+		return error;
+
+	sysdev->id = 0;
+	sysdev->cls = &balloon_sysdev_class;
+
+	error = sysdev_register(sysdev);
+	if (error) {
+		sysdev_class_unregister(&balloon_sysdev_class);
+		return error;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(balloon_attrs); i++) {
+		error = sysdev_create_file(sysdev, balloon_attrs[i]);
+		if (error)
+			goto fail;
+	}
+
+	error = sysfs_create_group(&sysdev->kobj, &balloon_info_group);
+	if (error)
+		goto fail;
+
+	return 0;
+
+ fail:
+	while (--i >= 0)
+		sysdev_remove_file(sysdev, balloon_attrs[i]);
+	sysdev_unregister(sysdev);
+	sysdev_class_unregister(&balloon_sysdev_class);
+	return error;
+}
+
+static void unregister_balloon(struct sys_device *sysdev)
+{
+	int i;
+
+	sysfs_remove_group(&sysdev->kobj, &balloon_info_group);
+	for (i = 0; i < ARRAY_SIZE(balloon_attrs); i++)
+		sysdev_remove_file(sysdev, balloon_attrs[i]);
+	sysdev_unregister(sysdev);
+	sysdev_class_unregister(&balloon_sysdev_class);
+}
+
+static void balloon_sysfs_exit(void)
+{
+	unregister_balloon(&balloon_sysdev);
+}
+
+MODULE_LICENSE("GPL");