Comment 6 for bug 1071072

Additional info: when the corruption takes place, the following tessages appears in the syslog:

QQ kernel: [ 3368.436768] [drm] nouveau 0000:01:00.0: magic set 0:
QQ kernel: [ 3368.436779] [drm] nouveau 0000:01:00.0: 0x00408904: 0x04082002
QQ kernel: [ 3368.436784] [drm] nouveau 0000:01:00.0: 0x00408908: 0xc400c0c0
QQ kernel: [ 3368.436790] [drm] nouveau 0000:01:00.0: 0x0040890c: 0x40000e00
QQ kernel: [ 3368.436795] [drm] nouveau 0000:01:00.0: 0x00408910: 0xc0c00000
QQ kernel: [ 3368.436799] [drm] nouveau 0000:01:00.0: PGRAPH - TRAP_TEXTURE - TP0: Unhandled ustatus 0x00000003
QQ kernel: [ 3368.436803] [drm] nouveau 0000:01:00.0: PGRAPH - TRAP
QQ kernel: [ 3368.436812] [drm] nouveau 0000:01:00.0: PGRAPH - ch 4 (0x00016f0000) subc 3 class 0x8297 mthd 0x0f04 data 0x00000000
QQ kernel: [ 3368.436825] [drm] nouveau 0000:01:00.0: VM: trapped read at 0xc400c0c000 on ch 4 [0x000016f0] PGRAPH/TEXTURE/00 reason: PT_NOT_PRESENT
QQ kernel: [ 3368.461381] [drm] nouveau 0000:01:00.0: magic set 0:
QQ kernel: [ 3368.461387] [drm] nouveau 0000:01:00.0: 0x00408904: 0x04093f02
QQ kernel: [ 3368.461390] [drm] nouveau 0000:01:00.0: 0x00408908: 0xc400c0c0
QQ kernel: [ 3368.461394] [drm] nouveau 0000:01:00.0: 0x0040890c: 0x40000e00
QQ kernel: [ 3368.461397] [drm] nouveau 0000:01:00.0: 0x00408910: 0xc0c00000
QQ kernel: [ 3368.461400] [drm] nouveau 0000:01:00.0: PGRAPH - TRAP_TEXTURE - TP0: Unhandled ustatus 0x00000003
QQ kernel: [ 3368.461402] [drm] nouveau 0000:01:00.0: PGRAPH - TRAP
QQ kernel: [ 3368.461407] [drm] nouveau 0000:01:00.0: PGRAPH - ch 4 (0x00016f0000) subc 3 class 0x8297 mthd 0x0f04 data 0x00000000
QQ kernel: [ 3368.461417] [drm] nouveau 0000:01:00.0: VM: trapped read at 0xc400c0c000 on ch 4 [0x000016f0] PGRAPH/TEXTURE/00 reason: PT_NOT_PRESENT