Here it is:
2a6f1abbb48f1d90f20b8198c4894c0469468405 is the first bad commit
commit 2a6f1abbb48f1d90f20b8198c4894c0469468405
Author: Christian König <deathsimple@vodafone.de>
Date:   Sat Aug 11 15:00:30 2012 +0200

    drm/radeon: make page table updates async v2

    Currently doing the update with the CP.

    v2: Rebased on Jeromes bugfix. Make validity comparison
        more human readable.

    Signed-off-by: Christian König <deathsimple@vodafone.de>

:040000 040000 3ed3f64bd42f5f1000ab9e957df08f53e81e09d9
c5143cbc30add8e3472366fbdb84756d9cdcd035 M    drivers