diff --git a/mm/memory.c b/mm/memory.c
index 66bc51e75926884cbcaf17c5a03aab7e2d9ab5c1..220c27af14fd61579daf22ccb189a0fdea7cf736 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1051,6 +1051,17 @@ int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 	return ret;
 }
 
+/* Whether we should zap all COWed (private) pages too */
+static inline bool should_zap_cows(struct zap_details *details)
+{
+	/* By default, zap all pages */
+	if (!details)
+		return true;
+
+	/* Or, we zap COWed pages only if the caller wants to */
+	return !details->check_mapping;
+}
+
 static unsigned long zap_pte_range(struct mmu_gather *tlb,
 				struct vm_area_struct *vma, pmd_t *pmd,
 				unsigned long addr, unsigned long end,
@@ -1141,17 +1152,19 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 			continue;
 		}
 
-		/* If details->check_mapping, we leave swap entries. */
-		if (unlikely(details))
-			continue;
-
 		entry = pte_to_swp_entry(ptent);
-		if (!non_swap_entry(entry))
+		if (!non_swap_entry(entry)) {
+			/* Genuine swap entry, hence a private anon page */
+			if (!should_zap_cows(details))
+				continue;
 			rss[MM_SWAPENTS]--;
-		else if (is_migration_entry(entry)) {
+		} else if (is_migration_entry(entry)) {
 			struct page *page;
 
 			page = migration_entry_to_page(entry);
+			if (details && details->check_mapping &&
+			    details->check_mapping != page_rmapping(page))
+				continue;
 			rss[mm_counter(page)]--;
 			reliable_page_counter(page, mm, -1);
 		}