x86: A further fix to paging_log_dirty_op() -- do not unmap_domain_page(NULL)

Signed-off-by: Keir Fraser <keir.fraser@citrix.com>

diff --git a/xen/arch/x86/mm/paging.c b/xen/arch/x86/mm/paging.c
index 0df7376c24d5c6e160db020659d7d590d6623ef4..e9313e14f111605a72c23111c99a4bba05fc2e26 100644 (file)
--- a/xen/arch/x86/mm/paging.c
+++ b/xen/arch/x86/mm/paging.c
@@ -430,7 +430,8 @@ int paging_log_dirty_op(struct domain *d, struct xen_domctl_shadow_op *sc)
         if ( l3 )
             unmap_domain_page(l3);
     }
-    unmap_domain_page(l4);
+    if ( l4 )
+        unmap_domain_page(l4);
 
     if ( pages < sc->pages )
         sc->pages = pages;