[PATCH] malloc: Fix MALLOC_DEBUG

[Wilco Dijkstra]

MALLOC_DEBUG only works on locked arenas, so move the call to
check_inuse_chunk from __libc_free() to _int_free_chunk().
Regress now passes if MALLOC_DEBUG is enabled - OK for commit?

---

diff --git a/malloc/malloc.c b/malloc/malloc.c
index 17fef8c2adbd37dce9353c735f85a06f761b5a4f..b3f5a446461b607dd9181a2107d3e8809373e310 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -3460,8 +3460,6 @@ __libc_free (void *mem)
   if (__glibc_unlikely (misaligned_chunk (p)))
     return malloc_printerr_tail ("free(): invalid pointer");
 
-  check_inuse_chunk (arena_for_chunk (p), p);
-
 #if USE_TCACHE
   if (__glibc_likely (size < mp_.tcache_max_bytes && tcache != NULL))
     {
@@ -4678,6 +4676,8 @@ _int_free_merge_chunk (mstate av, mchunkptr p, INTERNAL_SIZE_T size)
 {
   mchunkptr nextchunk = chunk_at_offset(p, size);
 
+  check_inuse_chunk (av, p);
+
   /* Lightweight tests: check whether the block is already the
      top block.  */
   if (__glibc_unlikely (p == av->top))