mm/rmap: Fix anon_vma->degree ambiguity leading to double-reuse

[platform/kernel/linux-rpi.git] / include / linux / rmap.h

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index bf80adc..b89b4b8 100644 (file)
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -41,12 +41,15 @@ struct anon_vma {
        atomic_t refcount;
 
        /*
-        * Count of child anon_vmas and VMAs which points to this anon_vma.
+        * Count of child anon_vmas. Equals to the count of all anon_vmas that
+        * have ->parent pointing to this one, including itself.
         *
         * This counter is used for making decision about reusing anon_vma
         * instead of forking new one. See comments in function anon_vma_clone.
         */
-       unsigned degree;
+       unsigned long num_children;
+       /* Count of VMAs whose ->anon_vma pointer points to this object. */
+       unsigned long num_active_vmas;
 
        struct anon_vma *parent;        /* Parent of this anon_vma */