1 files changed, 7 insertions, 1 deletions

diff --git a/mm/rmap.c b/mm/rmap.c
index 9d2ba01bd4f9..92e6757f196e 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -381,7 +381,13 @@ vma_address(struct page *page, struct vm_area_struct *vma)
 unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
 {
         if (PageAnon(page)) {
-                if (vma->anon_vma->root != page_anon_vma(page)->root)
+                struct anon_vma *page__anon_vma = page_anon_vma(page);
+                /*
+                 * Note: swapoff's unuse_vma() is more efficient with this
+                 * check, and needs it to match anon_vma when KSM is active.
+                 */
+                if (!vma->anon_vma || !page__anon_vma ||
+                    vma->anon_vma->root != page__anon_vma->root)
                         return -EFAULT;
         } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) {
                 if (!vma->vm_file ||