Nouveau - Sep 2015 - oops in reservation_object_wait_timeout_rcu

BUG: unable to handle kernel paging request at ffffc90003161018
 IP: [<ffffffff8157d12c>] reservation_object_wait_timeout_rcu+0x35c/0x580
 PGD 13a89a067 PUD 13a89b067 PMD 136735067 PTE 0
 Oops: 0000 [#1] PREEMPT SMP 
 Modules linked in: ctr ccm rfcomm bnep arc4 iwldvm mac80211 binfmt_misc iwlwifi
cfg80211 rtsx_usb uvcvideo btusb btbcm btintel bluetooth videobuf2_vmalloc
videobuf2_memops videobuf2_core v4l2_common snd_hda_codec_hdmi videodev
snd_hda_codec_idt snd_hda_codec_generic dell_wmi snd_hda_intel sparse_keymap
dell_laptop dcdbas snd_hda_controller snd_hda_codec x86_pkg_temp_thermal
coretemp snd_hwdep snd_pcm snd_hda_core microcode snd_seq_midi
snd_seq_midi_event serio_raw snd_rawmidi snd_seq snd_timer snd_seq_device snd
lpc_ich soundcore parport_pc ppdev lp parport hid_generic nouveau mxm_wmi ttm
i915 psmouse i2c_algo_bit drm_kms_helper ahci libahci usbhid drm hid wmi video
 CPU: 1 PID: 920 Comm: Xorg Not tainted 4.1.2+ #57
 Hardware name: Dell Inc.          Inspiron 7720/04M3YM, BIOS A07 08/16/2012
 task: ffff880136dec2c0 ti: ffff880136de4000 task.ti: ffff880136de4000
 RIP: 0010:[<ffffffff8157d12c>]  [<ffffffff8157d12c>]
reservation_object_wait_timeout_rcu+0x35c/0x580
 RSP: 0018:ffff880136de7c78  EFLAGS: 00010246
 RAX: ffffc90003161000 RBX: ffff8800ab123b00 RCX: 00000000ab123200
 RDX: 00000000ab123200 RSI: 0000000000000000 RDI: ffffffff81c5be00
 RBP: ffff880136de7cd8 R08: 0000000000000000 R09: 0000000000000000
 R10: 0000000000000000 R11: ffff880136de7d80 R12: 0000000000000000
 R13: 0000000000001d4c R14: 000000000000c326 R15: ffff88003290a1b8
 FS:  00007f29a7237980(0000) GS:ffff88013f240000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: ffffc90003161018 CR3: 0000000032cf8000 CR4: 00000000001407e0
 Stack:
  ffffffff8157ce70 ffff8800336a8898 0000000136de7ca8 ffff88003290a250
  ffff88004711ce40 000000020190a3f0 ffff880136de7cd8 00000000fffffff0
  0000000000000000 ffff88003290a000 ffff88003290a3f0 0000000000000082
 Call Trace:
  [<ffffffff8157ce70>] ? reservation_object_wait_timeout_rcu+0xa0/0x580
  [<ffffffffa0349d9d>] nouveau_gem_ioctl_cpu_prep+0x6d/0x190 [nouveau]
  [<ffffffff812087db>] ? might_fault+0x8b/0xa0
  [<ffffffffa003ed25>] drm_ioctl+0x1a5/0x6b0 [drm]
  [<ffffffff8110d65d>] ? trace_hardirqs_on+0xd/0x10
  [<ffffffff8179f432>] ? _raw_spin_unlock_irqrestore+0x42/0x80
  [<ffffffffa033fb92>] nouveau_drm_ioctl+0x72/0xd0 [nouveau]
  [<ffffffff8125cab8>] do_vfs_ioctl+0x308/0x540
  [<ffffffff81268c05>] ? __fget+0x5/0x210
  [<ffffffff81268e7a>] ? __fget_light+0x2a/0xa0
  [<ffffffff8125cd71>] SyS_ioctl+0x81/0xa0
  [<ffffffff8179fd9b>] system_call_fastpath+0x16/0x73
 Code: d5 a1 81 be c7 03 00 00 48 c7 c7 25 d0 a1 81 c6 05 d0 66 7a 00 01 e8 34
eb b8 ff e9 f5 fd ff ff 0f 1f 80 00 00 00 00 48 8b 43 08 <48> 8b 40 18 48
85 c0 0f 84 c7 fd ff ff 48 89 df ff d0 84 c0 0f
 RIP  [<ffffffff8157d12c>] reservation_object_wait_timeout_rcu+0x35c/0x580
  RSP <ffff880136de7c78>
 CR2: ffffc90003161018
 ---[ end trace c4e9ff6a0281167a ]---


Happened once, while I was "testing" Portal.