diff --git a/Documentation/vm/ksm.txt b/Documentation/vm/ksm.txt
index f34a8ee6f860..0c64a81d6808 100644
--- a/Documentation/vm/ksm.txt
+++ b/Documentation/vm/ksm.txt
@@ -80,6 +80,20 @@ run              - set 0 to stop ksmd from running but keep merged pages,
                    Default: 0 (must be changed to 1 to activate KSM,
                                except if CONFIG_SYSFS is disabled)
 
+use_zero_pages   - specifies whether empty pages (i.e. allocated pages
+                   that only contain zeroes) should be treated specially.
+                   When set to 1, empty pages are merged with the kernel
+                   zero page(s) instead of with each other as it would
+                   happen normally. This can improve the performance on
+                   architectures with coloured zero pages, depending on
+                   the workload. Care should be taken when enabling this
+                   setting, as it can potentially degrade the performance
+                   of KSM for some workloads, for example if the checksums
+                   of pages candidate for merging match the checksum of
+                   an empty page. This setting can be changed at any time,
+                   it is only effective for pages merged after the change.
+                   Default: 0 (normal KSM behaviour as in earlier releases)
+
 The effectiveness of KSM and MADV_MERGEABLE is shown in /sys/kernel/mm/ksm/:
 
 pages_shared     - how many shared pages are being used
diff --git a/mm/ksm.c b/mm/ksm.c
index 9ae6011a41f8..28bc5ab2b979 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -223,6 +223,12 @@ static unsigned int ksm_thread_pages_to_scan = 100;
 /* Milliseconds ksmd should sleep between batches */
 static unsigned int ksm_thread_sleep_millisecs = 20;
 
+/* Checksum of an empty (zeroed) page */
+static unsigned int zero_checksum __read_mostly;
+
+/* Whether to merge empty (zeroed) pages with actual zero pages */
+static bool ksm_use_zero_pages __read_mostly;
+
 #ifdef CONFIG_NUMA
 /* Zeroed when merging across nodes is not allowed */
 static unsigned int ksm_merge_across_nodes = 1;
@@ -926,6 +932,7 @@ static int replace_page(struct vm_area_struct *vma, struct page *page,
 	struct mm_struct *mm = vma->vm_mm;
 	pmd_t *pmd;
 	pte_t *ptep;
+	pte_t newpte;
 	spinlock_t *ptl;
 	unsigned long addr;
 	int err = -EFAULT;
@@ -950,12 +957,22 @@ static int replace_page(struct vm_area_struct *vma, struct page *page,
 		goto out_mn;
 	}
 
-	get_page(kpage);
-	page_add_anon_rmap(kpage, vma, addr, false);
+	/*
+	 * No need to check ksm_use_zero_pages here: we can only have a
+	 * zero_page here if ksm_use_zero_pages was enabled alreaady.
+	 */
+	if (!is_zero_pfn(page_to_pfn(kpage))) {
+		get_page(kpage);
+		page_add_anon_rmap(kpage, vma, addr, false);
+		newpte = mk_pte(kpage, vma->vm_page_prot);
+	} else {
+		newpte = pte_mkspecial(pfn_pte(page_to_pfn(kpage),
+					       vma->vm_page_prot));
+	}
 
 	flush_cache_page(vma, addr, pte_pfn(*ptep));
 	ptep_clear_flush_notify(vma, addr, ptep);
-	set_pte_at_notify(mm, addr, ptep, mk_pte(kpage, vma->vm_page_prot));
+	set_pte_at_notify(mm, addr, ptep, newpte);
 
 	page_remove_rmap(page, false);
 	if (!page_mapped(page))
@@ -1467,6 +1484,23 @@ static void cmp_and_merge_page(struct page *page, struct rmap_item *rmap_item)
 		return;
 	}
 
+	/*
+	 * Same checksum as an empty page. We attempt to merge it with the
+	 * appropriate zero page if the user enabled this via sysfs.
+	 */
+	if (ksm_use_zero_pages && (checksum == zero_checksum)) {
+		struct vm_area_struct *vma;
+
+		vma = find_mergeable_vma(rmap_item->mm, rmap_item->address);
+		err = try_to_merge_one_page(vma, page,
+					    ZERO_PAGE(rmap_item->address));
+		/*
+		 * In case of failure, the page was not really empty, so we
+		 * need to continue. Otherwise we're done.
+		 */
+		if (!err)
+			return;
+	}
 	tree_rmap_item =
 		unstable_tree_search_insert(rmap_item, page, &tree_page);
 	if (tree_rmap_item) {
@@ -2233,6 +2267,28 @@ static ssize_t merge_across_nodes_store(struct kobject *kobj,
 KSM_ATTR(merge_across_nodes);
 #endif
 
+static ssize_t use_zero_pages_show(struct kobject *kobj,
+				struct kobj_attribute *attr, char *buf)
+{
+	return sprintf(buf, "%u\n", ksm_use_zero_pages);
+}
+static ssize_t use_zero_pages_store(struct kobject *kobj,
+				   struct kobj_attribute *attr,
+				   const char *buf, size_t count)
+{
+	int err;
+	bool value;
+
+	err = kstrtobool(buf, &value);
+	if (err)
+		return -EINVAL;
+
+	ksm_use_zero_pages = value;
+
+	return count;
+}
+KSM_ATTR(use_zero_pages);
+
 static ssize_t pages_shared_show(struct kobject *kobj,
 				 struct kobj_attribute *attr, char *buf)
 {
@@ -2290,6 +2346,7 @@ static struct attribute *ksm_attrs[] = {
 #ifdef CONFIG_NUMA
 	&merge_across_nodes_attr.attr,
 #endif
+	&use_zero_pages_attr.attr,
 	NULL,
 };
 
@@ -2304,6 +2361,11 @@ static int __init ksm_init(void)
 	struct task_struct *ksm_thread;
 	int err;
 
+	/* The correct value depends on page size and endianness */
+	zero_checksum = calc_checksum(ZERO_PAGE(0));
+	/* Default to false for backwards compatibility */
+	ksm_use_zero_pages = false;
+
 	err = ksm_slab_init();
 	if (err)
 		goto out;