What's wrong?

=========================================================

[eric@wenjia ~]$ ll -d /var/lib/mock/dist-foo-build-42-21/root/builddir/
drwx------ 2 torrent mock 4096 03-29 11:08 /var/lib/mock/dist-foo-build-42-21/root/builddir/

=========================================================
[root.log]
......
DEBUG util.py:60: creating dir: /var/lib/mock/dist-foo-build-42-21/root/builddir/build/RPMS
ERROR util.py:63: Could not create dir /var/lib/mock/dist-foo-build-42-21/root/builddir/build/RPMS. Error: [Errno 13] Permission denied: '/var/lib/mock/dist-foo-build-42-21/root/builddir/build'
Traceback (most recent call last):
File "/usr/lib/python2.6/site-packages/mock/util.py", line 61, in mkdirIfAbsent
os.makedirs(dirName)
File "/usr/lib/python2.6/os.py", line 150, in makedirs
makedirs(head, mode)
File "/usr/lib/python2.6/os.py", line 157, in makedirs
mkdir(name, mode)
OSError: [Errno 13] Permission denied: '/var/lib/mock/dist-foo-build-42-21/root/builddir/build'
DEBUG util.py:98: kill orphans