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-rw-r--r--include/linux/rmap.h12
1 files changed, 11 insertions, 1 deletions
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index be574506e6a9..d9d7e7e56352 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -37,6 +37,16 @@ struct anon_vma {
atomic_t refcount;
/*
+ * Count of child anon_vmas and VMAs which points to this anon_vma.
+ *
+ * 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;
+
+ struct anon_vma *parent; /* Parent of this anon_vma */
+
+ /*
* NOTE: the LSB of the rb_root.rb_node is set by
* mm_take_all_locks() _after_ taking the above lock. So the
* rb_root must only be read/written after taking the above lock
@@ -150,7 +160,7 @@ int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *);
static inline void anon_vma_merge(struct vm_area_struct *vma,
struct vm_area_struct *next)
{
- VM_BUG_ON(vma->anon_vma != next->anon_vma);
+ VM_BUG_ON_VMA(vma->anon_vma != next->anon_vma, vma);
unlink_anon_vmas(next);
}