diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 0f1e9ff6..b1871d3 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -18,6 +18,8 @@
 #include <linux/rcupdate.h>
 #include <linux/slab.h>
 #include <linux/swapops.h>
+#include <linux/ksm.h>
+#include <linux/mman.h>
 
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>
@@ -1275,22 +1277,34 @@
 	return 0;
 }
 
-void s390_enable_skey(void)
+int s390_enable_skey(void)
 {
 	struct mm_walk walk = { .pte_entry = __s390_enable_skey };
 	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma;
+	int rc = 0;
 
 	down_write(&mm->mmap_sem);
 	if (mm_use_skey(mm))
 		goto out_up;
 
 	mm->context.use_skey = 1;
+	for (vma = mm->mmap; vma; vma = vma->vm_next) {
+		if (ksm_madvise(vma, vma->vm_start, vma->vm_end,
+				MADV_UNMERGEABLE, &vma->vm_flags)) {
+			mm->context.use_skey = 0;
+			rc = -ENOMEM;
+			goto out_up;
+		}
+	}
+	mm->def_flags &= ~VM_MERGEABLE;
 
 	walk.mm = mm;
 	walk_page_range(0, TASK_SIZE, &walk);
 
 out_up:
 	up_write(&mm->mmap_sem);
+	return rc;
 }
 EXPORT_SYMBOL_GPL(s390_enable_skey);