Avoid race between unlabeling and re-use

de35165a · Frans Kaashoek · 5ab627d2 · de35165a
--- a/kernel/kalloc.cc
+++ b/kernel/kalloc.cc
@@ -126,6 +126,9 @@ kfree_pool(struct kmem *m, char *v)
  if (ALLOC_MEMSET && kinited && m->size <= 16384)
    memset(v, 1, m->size);

+  if (kinited)
+    mtunlabel(mtrace_label_block, v);
+
  r = (struct run*)v;
  for (;;) {
    auto headval = m->freelist.load();
@@ -135,8 +138,6 @@ kfree_pool(struct kmem *m, char *v)
  }

  m->nfree++;
-  if (kinited)
-    mtunlabel(mtrace_label_block, r);
 }

 static void