我升级到了 17.04，但遇到了一个问题：如果我让计算机闲置一整夜，Xorg 就会崩溃——显示器不会唤醒锁定屏幕，而且我不知道我的键盘是否被读取。我编写的记录器脚本报告：
PID USER COMMAND
1341 root [Xorg] <defunct>
我正在尝试解决这个问题，并且有两个问题：
- 我怎样才能恢复？
- 我该如何扫描这个？
这是错误，来自/var/log/syslog：
May 25 07:17:27 <snip> kernel: [83956.890420] BUG: unable to handle kernel NULL pointer dereference at 0000000000000020
May 25 07:17:27 <snip> kernel: [83956.890432] IP: dma_fence_wait_timeout+0x36/0xf0
May 25 07:17:27 <snip> kernel: [83956.890435] PGD 0
May 25 07:17:27 <snip> kernel: [83956.890435]
May 25 07:17:27 <snip> kernel: [83956.890439] Oops: 0000 [#1] SMP
May 25 07:17:27 <snip> kernel: [83956.890441] Modules linked in: ip6table_filter ip6_tables rfcomm bnep nls_iso8859_1 uvcvideo videobuf2_vmalloc videobuf2_memops btusb videobuf2_v4l2 btrtl btbcm videobuf2_core btintel videodev bluetooth snd_usb_audio input_leds media snd_usbmidi_lib wl(POE) alienware_wmi intel_rapl x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel snd_hda_codec_hdmi snd_hda_codec_realtek cfg80211 snd_hda_codec_generic snd_hda_intel snd_hda_codec kvm snd_hda_core snd_hwdep snd_pcm snd_seq_midi snd_seq_midi_event snd_rawmidi snd_seq snd_seq_device snd_timer shpchp serio_raw snd soundcore mei_me mei lpc_ich mac_hid irqbypass intel_cstate intel_rapl_perf parport_pc ppdev lp parport ip_tables x_tables autofs4 algif_skcipher af_alg uas usb_storage dm_crypt hid_generic usbhid hid crct10dif_pclmul crc32_pclmul ghash_clmulni_intel
May 25 07:17:27 <snip> kernel: [83956.890474] pcbc nouveau i915 mxm_wmi aesni_intel ttm i2c_algo_bit drm_kms_helper aes_x86_64 crypto_simd syscopyarea glue_helper sysfillrect cryptd sysimgblt fb_sys_fops psmouse ahci drm r8169 libahci mii wmi fjes video
May 25 07:17:27 <snip> kernel: [83956.890486] CPU: 7 PID: 1341 Comm: Xorg Tainted: P OE 4.10.0-21-generic #23-Ubuntu
May 25 07:17:27 <snip> kernel: [83956.890489] Hardware name: Alienware Alienware X51 R2/0PGRP5, BIOS A09 05/11/2015
May 25 07:17:27 <snip> kernel: [83956.890492] task: ffff9b64582fda00 task.stack: ffffaaffc3204000
May 25 07:17:27 <snip> kernel: [83956.890495] RIP: 0010:dma_fence_wait_timeout+0x36/0xf0
May 25 07:17:27 <snip> kernel: [83956.890497] RSP: 0018:ffffaaffc3207b60 EFLAGS: 00010206
May 25 07:17:27 <snip> kernel: [83956.890499] RAX: 0000000000000000 RBX: ffff9b6410b61780 RCX: ffffffffa4e2e600
May 25 07:17:27 <snip> kernel: [83956.890502] RDX: 7fffffffffffffff RSI: 0000000000000001 RDI: ffff9b645a9d50c0
May 25 07:17:27 <snip> kernel: [83956.890504] RBP: ffffaaffc3207b80 R08: 0000000000000000 R09: 0000000000000000
May 25 07:17:27 <snip> kernel: [83956.890510] R10: 00000000000006d7 R11: 0000000000000ec1 R12: ffff9b645a9d50c0
May 25 07:17:27 <snip> kernel: [83956.890512] R13: 0000000000000001 R14: 7fffffffffffffff R15: 0000000000000001
May 25 07:17:27 <snip> kernel: [83956.890515] FS: 00007f37a3585a40(0000) GS:ffff9b646fbc0000(0000) knlGS:0000000000000000
May 25 07:17:27 <snip> kernel: [83956.890518] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
May 25 07:17:27 <snip> kernel: [83956.890520] CR2: 0000000000000020 CR3: 0000000419394000 CR4: 00000000001406e0
May 25 07:17:27 <snip> kernel: [83956.890523] Call Trace:
May 25 07:17:27 <snip> kernel: [83956.890532] drm_atomic_helper_wait_for_fences+0x48/0x120 [drm_kms_helper]
May 25 07:17:27 <snip> kernel: [83956.890563] nv50_disp_atomic_commit+0x19c/0x2a0 [nouveau]
May 25 07:17:27 <snip> kernel: [83956.890573] drm_atomic_commit+0x4b/0x50 [drm]
May 25 07:17:27 <snip> kernel: [83956.890578] drm_atomic_helper_connector_dpms+0xf8/0x1c0 [drm_kms_helper]
May 25 07:17:27 <snip> kernel: [83956.890596] nouveau_connector_dpms+0x1f/0x30 [nouveau]
May 25 07:17:27 <snip> kernel: [83956.890604] drm_mode_connector_set_obj_prop+0x62/0x70 [drm]
May 25 07:17:27 <snip> kernel: [83956.890611] drm_mode_obj_set_property_ioctl+0x11e/0x160 [drm]
May 25 07:17:27 <snip> kernel: [83956.890618] drm_mode_connector_property_set_ioctl+0x3f/0x60 [drm]
May 25 07:17:27 <snip> kernel: [83956.890625] drm_ioctl+0x21b/0x4c0 [drm]
May 25 07:17:27 <snip> kernel: [83956.890632] ? drm_mode_connector_set_obj_prop+0x70/0x70 [drm]
May 25 07:17:27 <snip> kernel: [83956.890650] nouveau_drm_ioctl+0x74/0xc0 [nouveau]
May 25 07:17:27 <snip> kernel: [83956.890654] do_vfs_ioctl+0xa3/0x610
May 25 07:17:27 <snip> kernel: [83956.890656] ? vfs_read+0x11b/0x130
May 25 07:17:27 <snip> kernel: [83956.890659] SyS_ioctl+0x79/0x90
May 25 07:17:27 <snip> kernel: [83956.890662] entry_SYSCALL_64_fastpath+0x1e/0xad
May 25 07:17:27 <snip> kernel: [83956.890665] RIP: 0033:0x7f37a0f88987
May 25 07:17:27 <snip> kernel: [83956.890667] RSP: 002b:00007ffd28718548 EFLAGS: 00003246 ORIG_RAX: 0000000000000010
May 25 07:17:27 <snip> kernel: [83956.890670] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007f37a0f88987
May 25 07:17:27 <snip> kernel: [83956.890673] RDX: 00007ffd28718580 RSI: 00000000c01064ab RDI: 000000000000000e
May 25 07:17:27 <snip> kernel: [83956.890676] RBP: 0000000000000029 R08: 000055f2195337d0 R09: 0000000000000000
May 25 07:17:27 <snip> kernel: [83956.890678] R10: 000055f219498190 R11: 0000000000003246 R12: 000055f21853e110
May 25 07:17:27 <snip> kernel: [83956.890681] R13: 00007ffd2871861c R14: 000055f218461a88 R15: 00007ffd28719264
May 25 07:17:27 <snip> kernel: [83956.890684] Code: e5 41 56 41 55 41 54 53 0f 88 b0 00 00 00 49 89 fc 41 89 f5 49 89 d6 0f 1f 44 00 00 49 8b 44 24 08 41 0f b6 f5 4c 89 f2 4c 89 e7 <ff> 50 20 49 89 c5 0f 1f 44 00 00 5b 4c 89 e8 41 5c 41 5d 41 5e
May 25 07:17:27 <snip> kernel: [83956.890703] RIP: dma_fence_wait_timeout+0x36/0xf0 RSP: ffffaaffc3207b60
May 25 07:17:27 <snip> kernel: [83956.890705] CR2: 0000000000000020
May 25 07:17:27 <snip> kernel: [83956.893142] ---[ end trace e4e2eacea5808be2 ]---