s390/mm: disable KSM for storage key enabled pages

When storage keys are enabled unmerge already merged pages and prevent
new pages from being merged.

Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 15 insertions, 1 deletions

diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 0f1e9ff6bc12..b1871d39e46e 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 @@ static int __s390_enable_skey(pte_t *pte, unsigned long addr,
         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);