X freezes when I start glxgears. I can't move the mouse nor reset with ctrl-alt-canc.

I'm running master git mesa (last commit 150d4968e31e4600f9479c53f83d810b92b59cf7, st/xorg: Initialize pipe in the renderer), git radeon drivers, libdrm v2.4.15 and kernel v2.6.31.

"lspci -v" output:

01:00.0 VGA compatible controller: ATI Technologies Inc M56P [Radeon Mobility X1600] (prog-if 00 [VGA controller])                                                                                                          
        Subsystem: Toshiba America Info Systems Device ff10                                                   
        Flags: bus master, fast devsel, latency 0, IRQ 16                                                     
        Memory at d0000000 (32-bit, prefetchable) [size=256M]                                                 
        I/O ports at 2000 [size=256]                                                                          
        Memory at cfef0000 (32-bit, non-prefetchable) [size=64K]                                              
        [virtual] Expansion ROM at cfe00000 [disabled] [size=128K]                                            
        Capabilities: [50] Power Management version 2                                                         
        Capabilities: [58] Express Legacy Endpoint, MSI 00                                                    
        Capabilities: [80] MSI: Enable- Count=1/1 Maskable- 64bit+                                            
        Kernel modules: radeon        

Using git bisect I have identified the first bad commit as:

284a7af274bc148f112bd0ebb40583923ee26b49 is first bad commit
commit 284a7af274bc148f112bd0ebb40583923ee26b49
Author: Pauli Nieminen <suokkos@gmail.com>
Date:   Sun Sep 20 22:24:35 2009 +0300

    radeon: Fix legacy bo not to reuse dma buffers before refcount is 1.

    This should help detecting possible memory leaks with dma buffers and prevent
    possible visual corruption if data would be overwriten too early.


Reverting this commit fixes the problem.