Sorry for being a bit intrusive.

The crash I described in my previous mail happens every time I lauch two
consecutive xlocks with OpenGL animations. I've set the DRM_DEBUG flag,
and I get that:

(... tons of same lines)
[drm:pid355:drm_lock] 6 has lock
[drm:pid355:drm_ioctl] pid=355, cmd=0x8008642a, nr=0x2a, dev 0xc139f400, 
auth=1
[drm:pid355:drm_lock] 4 (pid 355) requests lock (0x00000006), flags = 
0x00000000
[drm:pid355:drm_lock] 4 has lock
[drm:pid355:drm_ioctl] pid=355, cmd=0x8008642a, nr=0x2a, dev 0xc139f400, 
auth=1
[drm:pid355:drm_lock] 6 (pid 355) requests lock (0x00000004), flags = 
0x00000000
[drm:pid355:drm_lock] 6 has lock
[drm:pid355:drm_ioctl] pid=355, cmd=0x8008642a, nr=0x2a, dev 0xc139f400, 
auth=1
[drm:pid355:drm_lock] 4 (pid 355) requests lock (0x00000006), flags = 
0x00000000
[drm:pid355:drm_lock] 4 has lock
[drm:pid355:drm_ioctl] pid=355, cmd=0x8008642a, nr=0x2a, dev 0xc139f400, 
auth=1
[drm:pid355:drm_lock] 6 (pid 355) requests lock (0x00000004), flags = 
0x00000000
[drm:pid355:drm_lock] 6 has lock
[drm:pid355:drm_ioctl] pid=355, cmd=0x8008642a, nr=0x2a, dev 0xc139f400, 
auth=1
[drm:pid355:drm_lock] 4 (pid 355) requests lock (0x00000006), flags = 
0x00000000
[drm:pid355:drm_lock] 4 has lock
[drm:pid355:drm_ioctl] pid=355, cmd=0x8008642a, nr=0x2a, dev 0xc139f400, 
auth=1
[drm:pid355:drm_lock] 6 (pid 355) requests lock (0x00000004), flags = 
0x00000000
[drm:pid355:drm_lock] 6 has lock
[drm:pid355:drm_ioctl] pid=355, cmd=0x8008642a, nr=0x2a, dev 0xc139f400, 
auth=1
[drm:pid355:drm_lock] 4 (pid 355) requests lock (0x00000006), flags = 
0x00000000
[drm:pid355:drm_lock] 4 has lock
[drm:pid355:drm_ioctl] pid=355, cmd=0x8008642a, nr=0x2a, dev 0xc139f400, 
auth=1
[drm:pid355:drm_lock] 6 (pid 355) requests lock (0x00000004), flags = 
0x00000000
[drm:pid355:drm_lock] 6 has lock
[drm:pid355:drm_ioctl] pid=355, cmd=0x8008642a, nr=0x2a, dev 0xc139f400, 
auth=1
[drm:pid355:drm_lock] 4 (pid 355) requests lock (0x00000006), flags = 
0x00000000
[drm:pid355:drm_lock] 4 has lock
[drm:pid355:drm_ioctl] pid=355, cmd=0x8008642a, nr=0x2a, dev 0xc139f400, 
auth=1
[drm:pid355:drm_lock] 6 (pid 355) requests lock (0x00000004), flags = 
0x00000000
[drm:pid355:drm_lock] 6 has lock
[drm:pid355:drm_ioctl] pid=355, cmd=0x8008642a, nr=0x2a, dev 0xc139f400, 
auth=1
[drm:pid355:drm_lock] 4 (pid 355) requests lock (0x00000006), flags = 
0x00000000
[drm:pid355:drm_lock] 4 has lock
[drm:pid355:drm_ioctl] pid=355, cmd=0x80086442, nr=0x42, dev 0xc139f400, 
auth=1
[drm:pid355:radeon_cp_stop]
[drm:pid355:radeon_do_cp_flush]
[drm:pid355:radeon_do_cp_idle]
[drm:pid355:radeon_do_cp_stop]
[drm:pid355:radeon_do_engine_reset]
[drm:pid355:radeon_do_cp_reset]
[drm:pid355:drm_close] open_count = 3
[drm:pid355:radeon_do_cp_idle]
[drm:pid355:drm_close_pid] pid = 355, device = 0xc139f400, open_count = 3
[drm:pid355:drm_close_pid] Process 355 dead, freeing lock for context 4
[drm:pid355:drm_close_pid] pid = 355, device = 0xc139f400, open_count = 3
[drm:pid355:drm_close_pid] pid = 355, device = 0xc139f400, open_count = 3
error: [drm:pid355:drm_close] *ERROR* can't find authenticator

Any further clue?

Thanks,
Vincent