Dead pointers do not own references

Otherwise they'll bounce on reference counts.

Dead pointers do not own references
d3adb158 · David Benjamin · d029a831 · d3adb158 · d3adb158
--- a/include/radix.hh
+++ b/include/radix.hh
@@ -44,7 +44,7 @@ class radix_node;
 * unlocked when the radix_range goes away.
 *
 * Once a pointer is dead, it stays dead until the containing
- * radix_node is deallocated.
+ * radix_node is deallocated. Dead pointers do not own references.
 *
 * Races:
 *

--- a/kernel/radix.cc
+++ b/kernel/radix.cc
@@ -60,7 +60,9 @@ radix_entry::release()
  if (is_null()) return;
  if (is_node()) {
    node()->do_gc();
-  } else {
+  } else if (state() != entry_dead) {
+    // Only decref live pointers. Dead ones are part of pages which
+    // were RCU-freed and no longer own references.
    elem()->decref();
  }
 }