On 02/18/2010 01:02 PM, Mel Gorman wrote:
struct anon_vma {
spinlock_t lock; /* Serialize access to vma list */
-#ifdef CONFIG_KSM
- atomic_t ksm_refcount;
-#endif
-#ifdef CONFIG_MIGRATION
- atomic_t migrate_refcount;
+#if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION)
+
+ /*
+ * The refcount is taken by either KSM or page migration
+ * to take a reference to an anon_vma when there is no
+ * guarantee that the vma of page tables will exist for
+ * the duration of the operation. A caller that takes
+ * the reference is responsible for clearing up the
+ * anon_vma if they are the last user on release
+ */
+ atomic_t refcount;
Calling it just refcount is probably confusing, since
the anon_vma is also referenced by being on the chain
with others.
Maybe "other_refcount" because it is refcounts taken
by things other than VMAs? I am sure there is a better
name possible...
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