malloc: Avoid taggig mmaped memory on free

Either the memory belongs to the dumped area, in which case we don't
want to tag (the dumped area has the same tag as malloc internal data
so tagging is unnecessary, but chunks there may not have the right
alignment for the tag granule), or the memory will be unmapped
immediately (and thus tagging is not useful).

Reviewed-by: DJ Delorie <dj@redhat.com>

diff --git a/malloc/malloc.c b/malloc/malloc.c
index 61c25d0f935bd1377c1101d959b6079e0d53eecd..ecb87350b0bfac995075bb3427368e6c28caad49 100644 (file)
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -3284,9 +3284,6 @@ __libc_free (void *mem)
 
   p = mem2chunk (mem);
 
-  /* Mark the chunk as belonging to the library again.  */
-  (void)TAG_REGION (chunk2rawmem (p), CHUNK_AVAILABLE_SIZE (p) - CHUNK_HDR_SZ);
-
   if (chunk_is_mmapped (p))                       /* release mmapped memory. */
     {
       /* See if the dynamic brk/mmap threshold needs adjusting.
@@ -3307,6 +3304,10 @@ __libc_free (void *mem)
     {
       MAYBE_INIT_TCACHE ();
 
+      /* Mark the chunk as belonging to the library again.  */
+      (void)TAG_REGION (chunk2rawmem (p),
+                       CHUNK_AVAILABLE_SIZE (p) - CHUNK_HDR_SZ);
+
       ar_ptr = arena_for_chunk (p);
       _int_free (ar_ptr, p, 0);
     }