Same issue for me here on 2 different Dell OptiPlex 9020 (Haswell) and a Haswell Intel NUC. All recently upgraded to 14.10 
It appears to be very intermittent, about once a week on each different machine. Only seems to occur when left idle for some period of time, never when I’m actually using the machines. 

Nov  2 15:14:42 fox kernel: [12674.466186] ------------[ cut here ]------------
Nov  2 15:14:42 fox kernel: [12674.466221] WARNING: CPU: 0 PID: 2479 at /build/buildd/linux-3.16.0/drivers/gpu/drm/i915/intel_display.c:
3324 intel_crtc_wait_for_pending_flips+0x16c/0x180 [i915]()
Nov  2 15:14:42 fox kernel: [12674.466222] Modules linked in: pci_stub vboxpci(OE) vboxnetadp(OE) vboxnetflt(OE) vboxdrv(OE) autofs4 xt_
addrtype xt_conntrack ipt_MASQUERADE iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack bridge stp llc aufs ip
table_filter ip_tables x_tables snd_usb_audio snd_usbmidi_lib joydev snd_hda_codec_hdmi intel_rapl x86_pkg_temp_thermal intel_powerclamp
 snd_hda_intel snd_hda_controller dcdbas snd_hda_codec snd_hwdep snd_pcm rfcomm btusb kvm_intel snd_seq_midi snd_seq_midi_event bnep kvm
 bluetooth 6lowpan_iphc serio_raw lpc_ich snd_rawmidi snd_seq snd_seq_device snd_timer parport_pc snd rpcsec_gss_krb5 mei_me mei ppdev m
ac_hid binfmt_misc shpchp nfsd coretemp soundcore auth_rpcgss lp nfs_acl parport nfs lockd sunrpc fscache nls_iso8859_1 uas usb_storage 
dm_crypt hid_generic usbhid hid crct10dif_pclmul crc32_pclmul ghash_clmulni_intel i915 aesni_intel aes_x86_64 lrw gf128mul glue_helper a
blk_helper cryptd i2c_algo_bit psmouse ahci e1000e drm_kms_helper libahci drm ptp pps_core video
Nov  2 15:14:42 fox kernel: [12674.466258] CPU: 0 PID: 2479 Comm: Xorg Tainted: G           OE 3.16.0-24-generic #32-Ubuntu
Nov  2 15:14:42 fox kernel: [12674.466259] Hardware name: Dell Inc. OptiPlex 9020/0PC5F7, BIOS A07 04/25/2014
Nov  2 15:14:42 fox kernel: [12674.466260]  0000000000000009 ffff8807eec8fc18 ffffffff8277fcbc 0000000000000000
Nov  2 15:14:42 fox kernel: [12674.466261]  ffff8807eec8fc50 ffffffff8206fd8d 0000000000000000 ffff8807ed3ce000
Nov  2 15:14:42 fox kernel: [12674.466263]  ffff8807ec348210 ffff8807ec529000 ffff8807ec529000 ffff8807eec8fc60
Nov  2 15:14:42 fox kernel: [12674.466265] Call Trace:
Nov  2 15:14:42 fox kernel: [12674.466272]  [<ffffffff8277fcbc>] dump_stack+0x45/0x56
Nov  2 15:14:42 fox kernel: [12674.466276]  [<ffffffff8206fd8d>] warn_slowpath_common+0x7d/0xa0
Nov  2 15:14:42 fox kernel: [12674.466278]  [<ffffffff8206fe6a>] warn_slowpath_null+0x1a/0x20
Nov  2 15:14:42 fox kernel: [12674.466288]  [<ffffffffc047dffc>] intel_crtc_wait_for_pending_flips+0x16c/0x180 [i915]
Nov  2 15:14:42 fox kernel: [12674.466292]  [<ffffffff820b9590>] ? prepare_to_wait_event+0x100/0x100
Nov  2 15:14:42 fox kernel: [12674.466302]  [<ffffffffc0480ac3>] intel_crtc_disable_planes+0x33/0x1c0 [i915]
Nov  2 15:14:42 fox kernel: [12674.466304]  [<ffffffff82784e5b>] ? __ww_mutex_lock+0x1b/0xb0
Nov  2 15:14:42 fox kernel: [12674.466313]  [<ffffffffc0481a17>] haswell_crtc_disable+0x57/0x2e0 [i915]
Nov  2 15:14:42 fox kernel: [12674.466314]  [<ffffffff82785ab2>] ? mutex_lock+0x12/0x30
Nov  2 15:14:42 fox kernel: [12674.466323]  [<ffffffffc0482457>] intel_crtc_update_dpms+0x67/0xa0 [i915]
Nov  2 15:14:42 fox kernel: [12674.466332]  [<ffffffffc0486ac9>] intel_connector_dpms+0x59/0x70 [i915]
Nov  2 15:14:42 fox kernel: [12674.466342]  [<ffffffffc0254e19>] drm_mode_obj_set_property_ioctl+0x399/0x3a0 [drm]
Nov  2 15:14:42 fox kernel: [12674.466349]  [<ffffffffc0254e50>] drm_mode_connector_property_set_ioctl+0x30/0x40 [drm]
Nov  2 15:14:42 fox kernel: [12674.466354]  [<ffffffffc0243a4f>] drm_ioctl+0x1df/0x680 [drm]
Nov  2 15:14:42 fox kernel: [12674.466358]  [<ffffffff821f4bc8>] do_vfs_ioctl+0x2c8/0x4a0
Nov  2 15:14:42 fox kernel: [12674.466360]  [<ffffffff821e31a1>] ? __sb_end_write+0x31/0x60
Nov  2 15:14:42 fox kernel: [12674.466362]  [<ffffffff821e0d12>] ? vfs_write+0x1b2/0x1f0
Nov  2 15:14:42 fox kernel: [12674.466363]  [<ffffffff821f4e21>] SyS_ioctl+0x81/0xa0
Nov  2 15:14:42 fox kernel: [12674.466366]  [<ffffffff82787ced>] system_call_fastpath+0x1a/0x1f
Nov  2 15:14:42 fox kernel: [12674.466366] ---[ end trace 559f1719e7601098 ]---