Created attachment 77123 [details]
Kernel logs with drm.debug=2 nouveau.debug=trace

With 3.9-rc kernels X freezes after resume from s2ram. After ~10 seconds X is
restarted.

When this happens the following is printed in the kernel logs:

nouveau E[Xorg[1218]] failed to idle channel 0xcccc0000 [Xorg[1218]]
nouveau E[     PFB][0000:01:00.0] trapped read at 0x002001e020 on channel
0x00007b23 [unknown] SEMAPHORE_BG/PFIFO_READ/00 reason: PAGE_NOT_PRESENT
nouveau E[   PFIFO][0000:01:00.0] CACHE_ERROR - ch 2 [Xorg[1218]] subc 7 mthd
0x1280 data 0x00000000
nouveau E[  PGRAPH][0000:01:00.0] TRAP_TPDMA - TP0: Unhandled ustatus
0x00000004
nouveau E[  PGRAPH][0000:01:00.0]  TRAP
nouveau E[  PGRAPH][0000:01:00.0] ch 2 [0x0007b23000 Xorg[1218]] subc 7 class
0x8297 mthd 0x15e0 data 0x00000000
nouveau E[  PGRAPH][0000:01:00.0] TRAP_TPDMA_2D - TP 0 - Unknown fault at
address 0020339000
nouveau E[  PGRAPH][0000:01:00.0] TRAP_TPDMA_2D - TP 0 - e0c: 00000000, e18:
00000000, e1c: 00000000, e20: 00000011, e24: 0c030000
...

Full log attached.

Hardware is GeForce 8400M GS (10de:0427).