diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index f0c68b6b6154..4e6692380deb 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -460,6 +460,14 @@ struct zone {
 	seqlock_t		span_seqlock;
 #endif
 
+#ifdef CONFIG_PAGE_REPORTING
+	/*
+	 * Pointer to reported page tracking statistics array. The size of
+	 * the array is MAX_ORDER - PAGE_REPORTING_MIN_ORDER. NULL when
+	 * unused page reporting is not present.
+	 */
+	unsigned long		*reported_pages;
+#endif
 	int initialized;
 
 	/* Write-intensive fields used from the page allocator */
@@ -535,6 +543,14 @@ enum zone_flags {
 	ZONE_BOOSTED_WATERMARK,		/* zone recently boosted watermarks.
 					 * Cleared when kswapd is woken.
 					 */
+	ZONE_PAGE_REPORTING_REQUESTED,	/* zone enabled page reporting and has
+					 * requested flushing the data out of
+					 * higher order pages.
+					 */
+	ZONE_PAGE_REPORTING_ACTIVE,	/* zone enabled page reporting and is
+					 * activly flushing the data out of
+					 * higher order pages.
+					 */
 };
 
 static inline unsigned long zone_managed_pages(struct zone *zone)
@@ -755,6 +771,8 @@ static inline bool pgdat_is_empty(pg_data_t *pgdat)
 	return !pgdat->node_start_pfn && !pgdat->node_spanned_pages;
 }
 
+#include <linux/page_reporting.h>
+
 /* Used for pages not on another list */
 static inline void add_to_free_list(struct page *page, struct zone *zone,
 				    unsigned int order, int migratetype)
@@ -769,10 +787,16 @@ static inline void add_to_free_list(struct page *page, struct zone *zone,
 static inline void add_to_free_list_tail(struct page *page, struct zone *zone,
 					 unsigned int order, int migratetype)
 {
-	struct free_area *area = &zone->free_area[order];
+	struct list_head *tail = get_unreported_tail(zone, order, migratetype);
 
-	list_add_tail(&page->lru, &area->free_list[migratetype]);
-	area->nr_free++;
+	/*
+	 * To prevent the unreported pages from being interleaved with the
+	 * reported ones while we are actively processing pages we will use
+	 * the head of the reported pages to determine the tail of the free
+	 * list.
+	 */
+	list_add_tail(&page->lru, tail);
+	zone->free_area[order].nr_free++;
 }
 
 /* Used for pages which are on another list */
@@ -781,12 +805,22 @@ static inline void move_to_free_list(struct page *page, struct zone *zone,
 {
 	struct free_area *area = &zone->free_area[order];
 
+	/*
+	 * Clear Hinted flag, if present, to avoid placing reported pages
+	 * at the top of the free_list. It is cheaper to just process this
+	 * page again than to walk around a page that is already reported.
+	 */
+	clear_page_reported(page, zone);
+
 	list_move(&page->lru, &area->free_list[migratetype]);
 }
 
 static inline void del_page_from_free_list(struct page *page, struct zone *zone,
 					   unsigned int order)
 {
+	/* Clear Reported flag, if present, before resetting page type */
+	clear_page_reported(page, zone);
+
 	list_del(&page->lru);
 	__ClearPageBuddy(page);
 	set_page_private(page, 0);
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index f91cb8898ff0..759a3b3956f2 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -163,6 +163,9 @@ enum pageflags {
 
 	/* non-lru isolated movable page */
 	PG_isolated = PG_reclaim,
+
+	/* Buddy pages. Used to track which pages have been reported */
+	PG_reported = PG_uptodate,
 };
 
 #ifndef __GENERATING_BOUNDS_H
@@ -432,6 +435,14 @@ static inline bool set_hwpoison_free_buddy_page(struct page *page)
 #endif
 
 /*
+ * PageReported() is used to track reported free pages within the Buddy
+ * allocator. We can use the non-atomic version of the test and set
+ * operations as both should be shielded with the zone lock to prevent
+ * any possible races on the setting or clearing of the bit.
+ */
+__PAGEFLAG(Reported, reported, PF_NO_COMPOUND)
+
+/*
  * On an anonymous page mapped into a user virtual memory area,
  * page->mapping points to its anon_vma, not to a struct address_space;
  * with the PAGE_MAPPING_ANON bit set to distinguish it.  See rmap.h.
diff --git a/include/linux/page_reporting.h b/include/linux/page_reporting.h
new file mode 100644
index 000000000000..498bde6ea764
--- /dev/null
+++ b/include/linux/page_reporting.h
@@ -0,0 +1,138 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_PAGE_REPORTING_H
+#define _LINUX_PAGE_REPORTING_H
+
+#include <linux/mmzone.h>
+#include <linux/jump_label.h>
+#include <linux/pageblock-flags.h>
+#include <asm/pgtable_types.h>
+
+#define PAGE_REPORTING_MIN_ORDER	pageblock_order
+#define PAGE_REPORTING_HWM		32
+
+#ifdef CONFIG_PAGE_REPORTING
+struct page_reporting_dev_info {
+	/* function that alters pages to make them "reported" */
+	void (*report)(struct page_reporting_dev_info *phdev,
+		       unsigned int nents);
+
+	/* scatterlist containing pages to be processed */
+	struct scatterlist *sg;
+
+	/*
+	 * Upper limit on the number of pages that the react function
+	 * expects to be placed into the batch list to be processed.
+	 */
+	unsigned long capacity;
+
+	/* work struct for processing reports */
+	struct delayed_work work;
+
+	/*
+	 * The number of zones requesting reporting, plus one additional if
+	 * processing thread is active.
+	 */
+	atomic_t refcnt;
+};
+
+extern struct static_key page_reporting_notify_enabled;
+
+/* Boundary functions */
+struct list_head *__page_reporting_get_boundary(unsigned int order,
+						int migratetype);
+void page_reporting_del_from_boundary(struct page *page, struct zone *zone);
+void page_reporting_add_to_boundary(struct page *page, struct zone *zone,
+				    int migratetype);
+
+/* Hinted page accessors, defined in page_alloc.c */
+struct page *get_unreported_page(struct zone *zone, unsigned int order,
+				 int migratetype);
+void put_reported_page(struct zone *zone, struct page *page);
+
+void __page_reporting_request(struct zone *zone);
+void __page_reporting_free_stats(struct zone *zone);
+
+/* Tear-down and bring-up for page reporting devices */
+void page_reporting_shutdown(struct page_reporting_dev_info *phdev);
+int page_reporting_startup(struct page_reporting_dev_info *phdev);
+#endif /* CONFIG_PAGE_REPORTING */
+
+static inline struct list_head *
+get_unreported_tail(struct zone *zone, unsigned int order, int migratetype)
+{
+#ifdef CONFIG_PAGE_REPORTING
+	if (order >= PAGE_REPORTING_MIN_ORDER &&
+	    test_bit(ZONE_PAGE_REPORTING_ACTIVE, &zone->flags))
+		return __page_reporting_get_boundary(order, migratetype);
+#endif
+	return &zone->free_area[order].free_list[migratetype];
+}
+
+static inline void clear_page_reported(struct page *page,
+				     struct zone *zone)
+{
+#ifdef CONFIG_PAGE_REPORTING
+	if (likely(!PageReported(page)))
+		return;
+
+	/* push boundary back if we removed the upper boundary */
+	if (test_bit(ZONE_PAGE_REPORTING_ACTIVE, &zone->flags))
+		page_reporting_del_from_boundary(page, zone);
+
+	__ClearPageReported(page);
+
+	/* page_private will contain the page order, so just use it directly */
+	zone->reported_pages[page_private(page) - PAGE_REPORTING_MIN_ORDER]--;
+#endif
+}
+
+/* Free reported_pages and reset reported page tracking count to 0 */
+static inline void page_reporting_reset(struct zone *zone)
+{
+#ifdef CONFIG_PAGE_REPORTING
+	if (zone->reported_pages)
+		__page_reporting_free_stats(zone);
+#endif
+}
+
+/**
+ * page_reporting_notify_free - Free page notification to start page processing
+ * @zone: Pointer to current zone of last page processed
+ * @order: Order of last page added to zone
+ *
+ * This function is meant to act as a screener for __page_reporting_request
+ * which will determine if a give zone has crossed over the high-water mark
+ * that will justify us beginning page treatment. If we have crossed that
+ * threshold then it will start the process of pulling some pages and
+ * placing them in the batch list for treatment.
+ */
+static inline void page_reporting_notify_free(struct zone *zone, int order)
+{
+#ifdef CONFIG_PAGE_REPORTING
+	unsigned long nr_reported;
+
+	/* Called from hot path in __free_one_page() */
+	if (!static_key_false(&page_reporting_notify_enabled))
+		return;
+
+	/* Limit notifications only to higher order pages */
+	if (order < PAGE_REPORTING_MIN_ORDER)
+		return;
+
+	/* Do not bother with tests if we have already requested reporting */
+	if (test_bit(ZONE_PAGE_REPORTING_REQUESTED, &zone->flags))
+		return;
+
+	/* If reported_pages is not populated, assume 0 */
+	nr_reported = zone->reported_pages ?
+		    zone->reported_pages[order - PAGE_REPORTING_MIN_ORDER] : 0;
+
+	/* Only request it if we have enough to begin the page reporting */
+	if (zone->free_area[order].nr_free < nr_reported + PAGE_REPORTING_HWM)
+		return;
+
+	/* This is slow, but should be called very rarely */
+	__page_reporting_request(zone);
+#endif
+}
+#endif /*_LINUX_PAGE_REPORTING_H */
diff --git a/mm/Kconfig b/mm/Kconfig
index 56cec636a1fc..f5c68bba522f 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -237,6 +237,11 @@ config COMPACTION
           linux-mm@kvack.org.
 
 #
+# support for unused page reporting
+config PAGE_REPORTING
+	bool
+
+#
 # support for page migration
 #
 config MIGRATION
diff --git a/mm/Makefile b/mm/Makefile
index d0b295c3b764..1e17ba0ed2f0 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -105,3 +105,4 @@ obj-$(CONFIG_PERCPU_STATS) += percpu-stats.o
 obj-$(CONFIG_ZONE_DEVICE) += memremap.o
 obj-$(CONFIG_HMM_MIRROR) += hmm.o
 obj-$(CONFIG_MEMFD_CREATE) += memfd.o
+obj-$(CONFIG_PAGE_REPORTING) += page_reporting.o
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 9a82e12bd0e7..3acd2c3e53b3 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1608,6 +1608,7 @@ static int __ref __offline_pages(unsigned long start_pfn,
 	if (!populated_zone(zone)) {
 		zone_pcp_reset(zone);
 		build_all_zonelists(NULL);
+		page_reporting_reset(zone);
 	} else
 		zone_pcp_update(zone);
 
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 71aadc7d5ff6..69b848e5b83f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -68,6 +68,7 @@
 #include <linux/lockdep.h>
 #include <linux/nmi.h>
 #include <linux/psi.h>
+#include <linux/page_reporting.h>
 
 #include <asm/sections.h>
 #include <asm/tlbflush.h>
@@ -915,7 +916,7 @@ static inline struct capture_control *task_capc(struct zone *zone)
 static inline void __free_one_page(struct page *page,
 		unsigned long pfn,
 		struct zone *zone, unsigned int order,
-		int migratetype)
+		int migratetype, bool reported)
 {
 	struct capture_control *capc = task_capc(zone);
 	unsigned long uninitialized_var(buddy_pfn);
@@ -990,11 +991,20 @@ static inline void __free_one_page(struct page *page,
 done_merging:
 	set_page_order(page, order);
 
-	if (is_shuffle_order(order) ? shuffle_add_to_tail() :
-	    buddy_merge_likely(pfn, buddy_pfn, page, order))
+	if (reported ||
+	    (is_shuffle_order(order) ? shuffle_add_to_tail() :
+	     buddy_merge_likely(pfn, buddy_pfn, page, order)))
 		add_to_free_list_tail(page, zone, order, migratetype);
 	else
 		add_to_free_list(page, zone, order, migratetype);
+
+	/*
+	 * No need to notify on a reported page as the total count of
+	 * unreported pages will not have increased since we have essentially
+	 * merged the reported page with one or more unreported pages.
+	 */
+	if (!reported)
+		page_reporting_notify_free(zone, order);
 }
 
 /*
@@ -1305,7 +1315,7 @@ static void free_pcppages_bulk(struct zone *zone, int count,
 		if (unlikely(isolated_pageblocks))
 			mt = get_pageblock_migratetype(page);
 
-		__free_one_page(page, page_to_pfn(page), zone, 0, mt);
+		__free_one_page(page, page_to_pfn(page), zone, 0, mt, false);
 		trace_mm_page_pcpu_drain(page, 0, mt);
 	}
 	spin_unlock(&zone->lock);
@@ -1321,7 +1331,7 @@ static void free_one_page(struct zone *zone,
 		is_migrate_isolate(migratetype))) {
 		migratetype = get_pfnblock_migratetype(page, pfn);
 	}
-	__free_one_page(page, pfn, zone, order, migratetype);
+	__free_one_page(page, pfn, zone, order, migratetype, false);
 	spin_unlock(&zone->lock);
 }
 
@@ -2183,6 +2193,122 @@ struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
 	return NULL;
 }
 
+#ifdef CONFIG_PAGE_REPORTING
+/**
+ * get_unreported_page - Pull an unreported page from the free_list
+ * @zone: Zone to draw pages from
+ * @order: Order to draw pages from
+ * @mt: Migratetype to draw pages from
+ *
+ * This function will obtain a page from the free list. It will start by
+ * attempting to pull from the tail of the free list and if that is already
+ * reported on it will instead pull the head if that is unreported.
+ *
+ * The page will have the migrate type and order stored in the page
+ * metadata. While being processed the page will not be avaialble for
+ * allocation.
+ *
+ * Return: page pointer if raw page found, otherwise NULL
+ */
+struct page *get_unreported_page(struct zone *zone, unsigned int order, int mt)
+{
+	struct list_head *tail = get_unreported_tail(zone, order, mt);
+	struct free_area *area = &(zone->free_area[order]);
+	struct list_head *list = &area->free_list[mt];
+	struct page *page;
+
+	/* zone lock should be held when this function is called */
+	lockdep_assert_held(&zone->lock);
+
+	/* Find a page of the appropriate size in the preferred list */
+	page = list_last_entry(tail, struct page, lru);
+	list_for_each_entry_from_reverse(page, list, lru) {
+		/* If we entered this loop then the "raw" list isn't empty */
+
+		/* If the page is reported try the head of the list */
+		if (PageReported(page)) {
+			page = list_first_entry(list, struct page, lru);
+
+			/*
+			 * If both the head and tail are reported then reset
+			 * the boundary so that we read as an empty list
+			 * next time and bail out.
+			 */
+			if (PageReported(page)) {
+				page_reporting_add_to_boundary(page, zone, mt);
+				break;
+			}
+		}
+
+		del_page_from_free_list(page, zone, order);
+
+		/* record migratetype and order within page */
+		set_pcppage_migratetype(page, mt);
+		set_page_private(page, order);
+
+		/*
+		 * Page will not be available for allocation while we are
+		 * processing it so update the freepage state.
+		 */
+		__mod_zone_freepage_state(zone, -(1 << order), mt);
+
+		return page;
+	}
+
+	return NULL;
+}
+
+/**
+ * put_reported_page - Return a now-reported page back where we got it
+ * @zone: Zone to return pages to
+ * @page: Page that was reported
+ *
+ * This function will pull the migratetype and order information out
+ * of the page and attempt to return it where it found it. If the page
+ * is added to the free list without changes we will mark it as being
+ * reported.
+ */
+void put_reported_page(struct zone *zone, struct page *page)
+{
+	unsigned int order, mt;
+	unsigned long pfn;
+
+	/* zone lock should be held when this function is called */
+	lockdep_assert_held(&zone->lock);
+
+	mt = get_pcppage_migratetype(page);
+	pfn = page_to_pfn(page);
+
+	if (unlikely(has_isolate_pageblock(zone) || is_migrate_isolate(mt))) {
+		mt = get_pfnblock_migratetype(page, pfn);
+		set_pcppage_migratetype(page, mt);
+	}
+
+	order = page_private(page);
+	set_page_private(page, 0);
+
+	__free_one_page(page, pfn, zone, order, mt, true);
+
+	/*
+	 * If page was comingled with another page we cannot consider
+	 * the result to be "reported" since part of the page hasn't been.
+	 * In this case we will simply exit and not update the "reported"
+	 * state. Instead just treat the result as a unreported page.
+	 */
+	if (!PageBuddy(page) || page_order(page) != order)
+		return;
+
+	/* update areated page accounting */
+	zone->reported_pages[order - PAGE_REPORTING_MIN_ORDER]++;
+
+	/* update boundary of new migratetype and record it */
+	page_reporting_add_to_boundary(page, zone, mt);
+
+	/* flag page as reported */
+	__SetPageReported(page);
+}
+#endif /* CONFIG_PAGE_REPORTING */
+
 /*
  * This array describes the order lists are fallen back to when
  * the free lists for the desirable migrate type are depleted
diff --git a/mm/page_reporting.c b/mm/page_reporting.c
new file mode 100644
index 000000000000..971138205ae5
--- /dev/null
+++ b/mm/page_reporting.c
@@ -0,0 +1,299 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/mm.h>
+#include <linux/mmzone.h>
+#include <linux/page-isolation.h>
+#include <linux/gfp.h>
+#include <linux/export.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/scatterlist.h>
+#include "internal.h"
+
+static struct page_reporting_dev_info __rcu *ph_dev_info __read_mostly;
+struct static_key page_reporting_notify_enabled;
+
+struct list_head *boundary[MAX_ORDER - PAGE_REPORTING_MIN_ORDER][MIGRATE_TYPES];
+
+static void page_reporting_reset_boundary(struct zone *zone, unsigned int order,
+					  unsigned int migratetype)
+{
+	boundary[order - PAGE_REPORTING_MIN_ORDER][migratetype] =
+			&zone->free_area[order].free_list[migratetype];
+}
+
+#define for_each_reporting_migratetype_order(_order, _type) \
+	for (_order = MAX_ORDER; _order-- != PAGE_REPORTING_MIN_ORDER;) \
+		for (_type = MIGRATE_TYPES; _type--;)
+
+static int page_reporting_populate_metadata(struct zone *zone)
+{
+	unsigned int order, mt;
+
+	/*
+	 * We need to make sure we have somewhere to store the tracking
+	 * data for how many reported pages are in the zone. To do that
+	 * we need to make certain zone->reported_pages is populated.
+	 */
+	if (!zone->reported_pages) {
+		zone->reported_pages =
+			kcalloc(MAX_ORDER - PAGE_REPORTING_MIN_ORDER,
+				sizeof(unsigned long),
+				GFP_KERNEL);
+		if (!zone->reported_pages)
+			return -ENOMEM;
+	}
+
+	/* Update boundary data to reflect the zone we are currently working */
+	for_each_reporting_migratetype_order(order, mt)
+		page_reporting_reset_boundary(zone, order, mt);
+
+	return 0;
+}
+
+struct list_head *__page_reporting_get_boundary(unsigned int order,
+						int migratetype)
+{
+	return boundary[order - PAGE_REPORTING_MIN_ORDER][migratetype];
+}
+
+void page_reporting_del_from_boundary(struct page *page, struct zone *zone)
+{
+	unsigned int order = page_private(page) - PAGE_REPORTING_MIN_ORDER;
+	int mt = get_pcppage_migratetype(page);
+	struct list_head **tail = &boundary[order][mt];
+
+	if (*tail == &page->lru)
+		*tail = page->lru.next;
+}
+
+void page_reporting_add_to_boundary(struct page *page, struct zone *zone,
+				    int migratetype)
+{
+	unsigned int order = page_private(page) - PAGE_REPORTING_MIN_ORDER;
+	struct list_head **tail = &boundary[order][migratetype];
+
+	*tail = &page->lru;
+}
+
+static unsigned int page_reporting_fill(struct zone *zone,
+					struct page_reporting_dev_info *phdev)
+{
+	struct scatterlist *sg = phdev->sg;
+	unsigned int order, mt, count = 0;
+
+	sg_init_table(phdev->sg, phdev->capacity);
+
+	for_each_reporting_migratetype_order(order, mt) {
+		struct page *page;
+
+		/*
+		 * Pull pages from free list until we have drained
+		 * it or we have reached capacity.
+		 */
+		while ((page = get_unreported_page(zone, order, mt))) {
+			sg_set_page(&sg[count], page, PAGE_SIZE << order, 0);
+
+			if (++count == phdev->capacity)
+				return count;
+		}
+	}
+
+	/* mark end of scatterlist due to underflow */
+	if (count)
+		sg_mark_end(&sg[count - 1]);
+
+	/*
+	 * If there are no longer enough free pages to fully populate
+	 * the scatterlist, then we can just shut it down for this zone.
+	 */
+	__clear_bit(ZONE_PAGE_REPORTING_REQUESTED, &zone->flags);
+	atomic_dec(&phdev->refcnt);
+
+	return count;
+}
+
+static void page_reporting_drain(struct zone *zone,
+				 struct page_reporting_dev_info *phdev)
+{
+	struct scatterlist *sg = phdev->sg;
+
+	/*
+	 * Drain the now reported pages back into their respective
+	 * free lists/areas. We assume at least one page is populated.
+	 */
+	do {
+		put_reported_page(zone, sg_page(sg));
+	} while (!sg_is_last(sg++));
+}
+
+/*
+ * The page reporting cycle consists of 4 stages, fill, report, drain, and idle.
+ * We will cycle through the first 3 stages until we fail to obtain any
+ * pages, in that case we will switch to idle.
+ */
+static void page_reporting_cycle(struct zone *zone,
+				 struct page_reporting_dev_info *phdev)
+{
+	/*
+	 * Guarantee boundaries and stats are populated before we
+	 * start placing reported pages in the zone.
+	 */
+	if (page_reporting_populate_metadata(zone))
+		return;
+
+	spin_lock(&zone->lock);
+
+	/* set bit indicating boundaries are present */
+	__set_bit(ZONE_PAGE_REPORTING_ACTIVE, &zone->flags);
+
+	do {
+		/* Pull pages out of allocator into a scaterlist */
+		unsigned int nents = page_reporting_fill(zone, phdev);
+
+		/* no pages were acquired, give up */
+		if (!nents)
+			break;
+
+		spin_unlock(&zone->lock);
+
+		/* begin processing pages in local list */
+		phdev->report(phdev, nents);
+
+		spin_lock(&zone->lock);
+
+		/*
+		 * We should have a scatterlist of pages that have been
+		 * processed. Return them to their original free lists.
+		 */
+		page_reporting_drain(zone, phdev);
+
+		/* keep pulling pages till there are none to pull */
+	} while (test_bit(ZONE_PAGE_REPORTING_REQUESTED, &zone->flags));
+
+	/* processing of the zone is complete, we can disable boundaries */
+	__clear_bit(ZONE_PAGE_REPORTING_ACTIVE, &zone->flags);
+
+	spin_unlock(&zone->lock);
+}
+
+static void page_reporting_process(struct work_struct *work)
+{
+	struct delayed_work *d_work = to_delayed_work(work);
+	struct page_reporting_dev_info *phdev =
+		container_of(d_work, struct page_reporting_dev_info, work);
+	struct zone *zone = first_online_pgdat()->node_zones;
+
+	do {
+		if (test_bit(ZONE_PAGE_REPORTING_REQUESTED, &zone->flags))
+			page_reporting_cycle(zone, phdev);
+
+		/*
+		 * Move to next zone, if at the end of the list
+		 * test to see if we can just go into idle.
+		 */
+		zone = next_zone(zone);
+		if (zone)
+			continue;
+		zone = first_online_pgdat()->node_zones;
+
+		/*
+		 * As long as refcnt has not reached zero there are still
+		 * zones to be processed.
+		 */
+	} while (atomic_read(&phdev->refcnt));
+}
+
+/* request page reporting on this zone */
+void __page_reporting_request(struct zone *zone)
+{
+	struct page_reporting_dev_info *phdev;
+
+	rcu_read_lock();
+
+	/*
+	 * We use RCU to protect the ph_dev_info pointer. In almost all
+	 * cases this should be present, however in the unlikely case of
+	 * a shutdown this will be NULL and we should exit.
+	 */
+	phdev = rcu_dereference(ph_dev_info);
+	if (unlikely(!phdev))
+		return;
+
+	/*
+	 * We can use separate test and set operations here as there
+	 * is nothing else that can set or clear this bit while we are
+	 * holding the zone lock. The advantage to doing it this way is
+	 * that we don't have to dirty the cacheline unless we are
+	 * changing the value.
+	 */
+	__set_bit(ZONE_PAGE_REPORTING_REQUESTED, &zone->flags);
+
+	/*
+	 * Delay the start of work to allow a sizable queue to
+	 * build. For now we are limiting this to running no more
+	 * than 10 times per second.
+	 */
+	if (!atomic_fetch_inc(&phdev->refcnt))
+		schedule_delayed_work(&phdev->work, HZ / 10);
+
+	rcu_read_unlock();
+}
+
+void __page_reporting_free_stats(struct zone *zone)
+{
+	/* free reported_page statisitics */
+	kfree(zone->reported_pages);
+	zone->reported_pages = NULL;
+}
+
+void page_reporting_shutdown(struct page_reporting_dev_info *phdev)
+{
+	if (rcu_access_pointer(ph_dev_info) != phdev)
+		return;
+
+	/* Disable page reporting notification */
+	static_key_slow_dec(&page_reporting_notify_enabled);
+	RCU_INIT_POINTER(ph_dev_info, NULL);
+	synchronize_rcu();
+
+	/* Flush any existing work, and lock it out */
+	cancel_delayed_work_sync(&phdev->work);
+
+	/* Free scatterlist */
+	kfree(phdev->sg);
+	phdev->sg = NULL;
+}
+EXPORT_SYMBOL_GPL(page_reporting_shutdown);
+
+int page_reporting_startup(struct page_reporting_dev_info *phdev)
+{
+	struct zone *zone;
+
+	/* nothing to do if already in use */
+	if (rcu_access_pointer(ph_dev_info))
+		return -EBUSY;
+
+	/* allocate scatterlist to store pages being reported on */
+	phdev->sg = kcalloc(phdev->capacity, sizeof(*phdev->sg), GFP_KERNEL);
+	if (!phdev->sg)
+		return -ENOMEM;
+
+	/* initialize refcnt and work structures */
+	atomic_set(&phdev->refcnt, 0);
+	INIT_DELAYED_WORK(&phdev->work, &page_reporting_process);
+
+	/* assign device, and begin initial flush of populated zones */
+	rcu_assign_pointer(ph_dev_info, phdev);
+	for_each_populated_zone(zone) {
+		spin_lock(&zone->lock);
+		__page_reporting_request(zone);
+		spin_unlock(&zone->lock);
+	}
+
+	/* enable page reporting notification */
+	static_key_slow_inc(&page_reporting_notify_enabled);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(page_reporting_startup);
+
