diff --git a/fs/block_dev.c b/fs/block_dev.c
index e123641..303b7cd 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -75,7 +75,7 @@ void kill_bdev(struct block_device *bdev)
 {
 	struct address_space *mapping = bdev->bd_inode->i_mapping;
 
-	if (mapping->nrpages == 0 && mapping->nrshadows == 0)
+	if (mapping->nrpages == 0 && mapping->nrexceptional == 0)
 		return;
 
 	invalidate_bh_lrus();
diff --git a/fs/inode.c b/fs/inode.c
index 4c8f719..6e3e5d0 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -495,7 +495,7 @@ void clear_inode(struct inode *inode)
 	 */
 	spin_lock_irq(&inode->i_data.tree_lock);
 	BUG_ON(inode->i_data.nrpages);
-	BUG_ON(inode->i_data.nrshadows);
+	BUG_ON(inode->i_data.nrexceptional);
 	spin_unlock_irq(&inode->i_data.tree_lock);
 	BUG_ON(!list_empty(&inode->i_data.private_list));
 	BUG_ON(!(inode->i_state & I_FREEING));
diff --git a/include/linux/dax.h b/include/linux/dax.h
index b415e52..e9d57f68 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -36,4 +36,9 @@ static inline bool vma_is_dax(struct vm_area_struct *vma)
 {
 	return vma->vm_file && IS_DAX(vma->vm_file->f_mapping->host);
 }
+
+static inline bool dax_mapping(struct address_space *mapping)
+{
+	return mapping->host && IS_DAX(mapping->host);
+}
 #endif
diff --git a/include/linux/fs.h b/include/linux/fs.h
index ddb7bad..fdab768 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -433,7 +433,8 @@ struct address_space {
 	struct rw_semaphore	i_mmap_rwsem;	/* protect tree, count, list */
 	/* Protected by tree_lock together with the radix tree */
 	unsigned long		nrpages;	/* number of total pages */
-	unsigned long		nrshadows;	/* number of shadow entries */
+	/* number of shadow or DAX exceptional entries */
+	unsigned long		nrexceptional;
 	pgoff_t			writeback_index;/* writeback starts here */
 	const struct address_space_operations *a_ops;	/* methods */
 	unsigned long		flags;		/* error bits/gfp mask */
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index 57e7d87..7c88ad1 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -51,6 +51,15 @@
 #define RADIX_TREE_EXCEPTIONAL_ENTRY	2
 #define RADIX_TREE_EXCEPTIONAL_SHIFT	2
 
+#define RADIX_DAX_MASK	0xf
+#define RADIX_DAX_SHIFT	4
+#define RADIX_DAX_PTE  (0x4 | RADIX_TREE_EXCEPTIONAL_ENTRY)
+#define RADIX_DAX_PMD  (0x8 | RADIX_TREE_EXCEPTIONAL_ENTRY)
+#define RADIX_DAX_TYPE(entry) ((unsigned long)entry & RADIX_DAX_MASK)
+#define RADIX_DAX_SECTOR(entry) (((unsigned long)entry >> RADIX_DAX_SHIFT))
+#define RADIX_DAX_ENTRY(sector, pmd) ((void *)((unsigned long)sector << \
+		RADIX_DAX_SHIFT | (pmd ? RADIX_DAX_PMD : RADIX_DAX_PTE)))
+
 static inline int radix_tree_is_indirect_ptr(void *ptr)
 {
 	return (int)((unsigned long)ptr & RADIX_TREE_INDIRECT_PTR);
diff --git a/mm/filemap.c b/mm/filemap.c
index 847ee43..7b8be78 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -11,6 +11,7 @@
  */
 #include <linux/export.h>
 #include <linux/compiler.h>
+#include <linux/dax.h>
 #include <linux/fs.h>
 #include <linux/uaccess.h>
 #include <linux/capability.h>
@@ -123,9 +124,9 @@ static void page_cache_tree_delete(struct address_space *mapping,
 	__radix_tree_lookup(&mapping->page_tree, page->index, &node, &slot);
 
 	if (shadow) {
-		mapping->nrshadows++;
+		mapping->nrexceptional++;
 		/*
-		 * Make sure the nrshadows update is committed before
+		 * Make sure the nrexceptional update is committed before
 		 * the nrpages update so that final truncate racing
 		 * with reclaim does not see both counters 0 at the
 		 * same time and miss a shadow entry.
@@ -579,9 +580,13 @@ static int page_cache_tree_insert(struct address_space *mapping,
 		p = radix_tree_deref_slot_protected(slot, &mapping->tree_lock);
 		if (!radix_tree_exceptional_entry(p))
 			return -EEXIST;
+
+		if (WARN_ON(dax_mapping(mapping)))
+			return -EINVAL;
+
 		if (shadowp)
 			*shadowp = p;
-		mapping->nrshadows--;
+		mapping->nrexceptional--;
 		if (node)
 			workingset_node_shadows_dec(node);
 	}
@@ -1245,9 +1250,9 @@ repeat:
 			if (radix_tree_deref_retry(page))
 				goto restart;
 			/*
-			 * A shadow entry of a recently evicted page,
-			 * or a swap entry from shmem/tmpfs.  Return
-			 * it without attempting to raise page count.
+			 * A shadow entry of a recently evicted page, a swap
+			 * entry from shmem/tmpfs or a DAX entry.  Return it
+			 * without attempting to raise page count.
 			 */
 			goto export;
 		}
diff --git a/mm/truncate.c b/mm/truncate.c
index 76e35ad..e3ee0e2 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -9,6 +9,7 @@
 
 #include <linux/kernel.h>
 #include <linux/backing-dev.h>
+#include <linux/dax.h>
 #include <linux/gfp.h>
 #include <linux/mm.h>
 #include <linux/swap.h>
@@ -34,31 +35,39 @@ static void clear_exceptional_entry(struct address_space *mapping,
 		return;
 
 	spin_lock_irq(&mapping->tree_lock);
-	/*
-	 * Regular page slots are stabilized by the page lock even
-	 * without the tree itself locked.  These unlocked entries
-	 * need verification under the tree lock.
-	 */
-	if (!__radix_tree_lookup(&mapping->page_tree, index, &node, &slot))
-		goto unlock;
-	if (*slot != entry)
-		goto unlock;
-	radix_tree_replace_slot(slot, NULL);
-	mapping->nrshadows--;
-	if (!node)
-		goto unlock;
-	workingset_node_shadows_dec(node);
-	/*
-	 * Don't track node without shadow entries.
-	 *
-	 * Avoid acquiring the list_lru lock if already untracked.
-	 * The list_empty() test is safe as node->private_list is
-	 * protected by mapping->tree_lock.
-	 */
-	if (!workingset_node_shadows(node) &&
-	    !list_empty(&node->private_list))
-		list_lru_del(&workingset_shadow_nodes, &node->private_list);
-	__radix_tree_delete_node(&mapping->page_tree, node);
+
+	if (dax_mapping(mapping)) {
+		if (radix_tree_delete_item(&mapping->page_tree, index, entry))
+			mapping->nrexceptional--;
+	} else {
+		/*
+		 * Regular page slots are stabilized by the page lock even
+		 * without the tree itself locked.  These unlocked entries
+		 * need verification under the tree lock.
+		 */
+		if (!__radix_tree_lookup(&mapping->page_tree, index, &node,
+					&slot))
+			goto unlock;
+		if (*slot != entry)
+			goto unlock;
+		radix_tree_replace_slot(slot, NULL);
+		mapping->nrexceptional--;
+		if (!node)
+			goto unlock;
+		workingset_node_shadows_dec(node);
+		/*
+		 * Don't track node without shadow entries.
+		 *
+		 * Avoid acquiring the list_lru lock if already untracked.
+		 * The list_empty() test is safe as node->private_list is
+		 * protected by mapping->tree_lock.
+		 */
+		if (!workingset_node_shadows(node) &&
+		    !list_empty(&node->private_list))
+			list_lru_del(&workingset_shadow_nodes,
+					&node->private_list);
+		__radix_tree_delete_node(&mapping->page_tree, node);
+	}
 unlock:
 	spin_unlock_irq(&mapping->tree_lock);
 }
@@ -228,7 +237,7 @@ void truncate_inode_pages_range(struct address_space *mapping,
 	int		i;
 
 	cleancache_invalidate_inode(mapping);
-	if (mapping->nrpages == 0 && mapping->nrshadows == 0)
+	if (mapping->nrpages == 0 && mapping->nrexceptional == 0)
 		return;
 
 	/* Offsets within partial pages */
@@ -402,7 +411,7 @@ EXPORT_SYMBOL(truncate_inode_pages);
  */
 void truncate_inode_pages_final(struct address_space *mapping)
 {
-	unsigned long nrshadows;
+	unsigned long nrexceptional;
 	unsigned long nrpages;
 
 	/*
@@ -416,14 +425,14 @@ void truncate_inode_pages_final(struct address_space *mapping)
 
 	/*
 	 * When reclaim installs eviction entries, it increases
-	 * nrshadows first, then decreases nrpages.  Make sure we see
+	 * nrexceptional first, then decreases nrpages.  Make sure we see
 	 * this in the right order or we might miss an entry.
 	 */
 	nrpages = mapping->nrpages;
 	smp_rmb();
-	nrshadows = mapping->nrshadows;
+	nrexceptional = mapping->nrexceptional;
 
-	if (nrpages || nrshadows) {
+	if (nrpages || nrexceptional) {
 		/*
 		 * As truncation uses a lockless tree lookup, cycle
 		 * the tree lock to make sure any ongoing tree
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 44ec50f..30e0cd7 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -46,6 +46,7 @@
 #include <linux/oom.h>
 #include <linux/prefetch.h>
 #include <linux/printk.h>
+#include <linux/dax.h>
 
 #include <asm/tlbflush.h>
 #include <asm/div64.h>
@@ -671,9 +672,15 @@ static int __remove_mapping(struct address_space *mapping, struct page *page,
 		 * inode reclaim needs to empty out the radix tree or
 		 * the nodes are lost.  Don't plant shadows behind its
 		 * back.
+		 *
+		 * We also don't store shadows for DAX mappings because the
+		 * only page cache pages found in these are zero pages
+		 * covering holes, and because we don't want to mix DAX
+		 * exceptional entries and shadow exceptional entries in the
+		 * same page_tree.
 		 */
 		if (reclaimed && page_is_file_cache(page) &&
-		    !mapping_exiting(mapping))
+		    !mapping_exiting(mapping) && !dax_mapping(mapping))
 			shadow = workingset_eviction(mapping, page);
 		__delete_from_page_cache(page, shadow, memcg);
 		spin_unlock_irqrestore(&mapping->tree_lock, flags);
diff --git a/mm/workingset.c b/mm/workingset.c
index aa01713..61ead9e 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -351,8 +351,8 @@ static enum lru_status shadow_lru_isolate(struct list_head *item,
 			node->slots[i] = NULL;
 			BUG_ON(node->count < (1U << RADIX_TREE_COUNT_SHIFT));
 			node->count -= 1U << RADIX_TREE_COUNT_SHIFT;
-			BUG_ON(!mapping->nrshadows);
-			mapping->nrshadows--;
+			BUG_ON(!mapping->nrexceptional);
+			mapping->nrexceptional--;
 		}
 	}
 	BUG_ON(node->count);
