However switching from intel to nvidia works ok thru a log out/in. A restart is needed when going from nvidia to intel.
This is basically what is shown on the screen when attempting a n intel to nvidia via a log out
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.022947] BUG: unable to handle kernel paging request at ffffffffc0d8a408
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.022977] IP: [<ffffffffc0061f68>] drm_gem_map_detach+0x28/0xc0 [drm]
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023014] PGD 2c0f067 PUD 2c11067 PMD 262fc3067 PTE 0
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023037] Oops: 0000 [#1] SMP
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023050] Modules linked in: rfcomm hid_logitech_hidpp bnep hid_logitech_dj btusb usbhid btrtl btbcm uvcvideo hid videobuf2_vmalloc videobuf2_memops btintel videobuf2_core v4l2_common bluetooth videodev media bbswitch(OE) nls_iso8859_1 arc4 iwlmvm mac80211 snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic intel_rapl iosf_mbi x86_pkg_temp_thermal intel_powerclamp coretemp snd_hda_intel snd_hda_codec kvm_intel snd_hda_core snd_hwdep kvm crct10dif_pclmul crc32_pclmul ghash_clmulni_intel aesni_intel aes_x86_64 lrw gf128mul glue_helper snd_pcm iwlwifi ablk_helper cryptd snd_seq_midi snd_seq_midi_event snd_rawmidi snd_seq snd_seq_device joydev snd_timer input_leds serio_raw snd soundcore cfg80211 mei_me lpc_ich mei ie31200_edac ideapad_laptop sparse_keymap edac_core shpchp wmi mac_hid parport_pc ppdev lp parport autofs4 uas usb_storage i915 i2c_algo_bit drm_kms_helper psmouse drm ahci libahci alx mdio video [last unloaded: nvidia]
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023432] CPU: 7 PID: 1982 Comm: Xorg Tainted: P OE 4.2.0-16-generic #19-Ubuntu
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023459] Hardware name: LENOVO 20217/VIQY0Y1, BIOS 74CN44WW(V3.05) 09/18/2013
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023482] task: ffff880073033700 ti: ffff880248ea0000 task.ti: ffff880248ea0000
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023506] RIP: 0010:[<ffffffffc0061f68>] [<ffffffffc0061f68>] drm_gem_map_detach+0x28/0xc0 [drm]
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023543] RSP: 0018:ffff880248ea3a38 EFLAGS: 00010292
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023560] RAX: ffffffffc0d8a2e0 RBX: ffff88026178b2f0 RCX: ffffffffc01d6340
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023582] RDX: ffff880260b61e10 RSI: ffff880265649180 RDI: ffff880261219180
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023603] RBP: ffff880248ea3a58 R08: 00000000641bdd01 R09: 0000000100200001
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023625] R10: ffff8802641bdd00 R11: 0000160000000000 R12: ffff880260b61e00
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023647] R13: ffff880265649180 R14: ffff8802601f0000 R15: ffff880035a8ead8
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023669] FS: 00007f4968b2b980(0000) GS:ffff88026f3c0000(0000) knlGS:0000000000000000
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023693] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023718] CR2: ffffffffc0d8a408 CR3: 000000007344f000 CR4: 00000000001406e0
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023734] Stack:
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023739] ffff8802601f0000 ffff880265649180 ffff880260b61e00 ffff880260b61e28
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023759] ffff880248ea3a88 ffffffff8157393f ffff880248ea3a88 ffff880265649180
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023778] ffff880260b61e00 ffff880035a8eb80 ffff880248ea3aa8 ffffffffc0061e40
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023797] Call Trace:
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023807] [<ffffffff8157393f>] dma_buf_detach+0x6f/0xb0
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023824] [<ffffffffc0061e40>] drm_prime_gem_destroy+0x30/0x40 [drm]
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023852] [<ffffffffc014eb5e>] i915_gem_free_object+0x16e/0x310 [i915]
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023869] [<ffffffff811ddcef>] ? kmem_cache_free+0x1cf/0x1e0
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023886] [<ffffffffc0048137>] drm_gem_object_free+0x27/0x30 [drm]
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023907] [<ffffffffc0147f76>] i915_gem_object_retire__read+0x1a6/0x210 [i915]
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023929] [<ffffffffc014a0ab>] i915_gem_retire_requests_ring+0x7b/0x140 [i915]
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023951] [<ffffffffc013eecc>] i915_gem_execbuffer_reserve+0x3c/0x320 [i915]
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023972] [<ffffffffc013fbc2>] i915_gem_do_execbuffer.isra.27+0x5d2/0x10a0 [i915]
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.023990] [<ffffffff811deabd>] ? __kmalloc+0x1ad/0x250
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.024007] [<ffffffffc0141792>] i915_gem_execbuffer2+0xb2/0x240 [i915]
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.024026] [<ffffffffc0049495>] drm_ioctl+0x125/0x610 [drm]
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.024041] [<ffffffff810e080d>] ? call_rcu_sched+0x1d/0x20
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.024058] [<ffffffffc01416e0>] ? i915_gem_execbuffer+0x310/0x310 [i915]
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.024075] [<ffffffff81213bc6>] ? dentry_free+0x56/0x90
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.024088] [<ffffffff81213fa6>] ? __dentry_kill+0x166/0x1f0
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.024102] [<ffffffff812108a5>] do_vfs_ioctl+0x295/0x480
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.024116] [<ffffffff8121d7a4>] ? mntput+0x24/0x40
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.024128] [<ffffffff811fef30>] ? __fput+0x190/0x220
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.024141] [<ffffffff81210b09>] SyS_ioctl+0x79/0x90
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.024154] [<ffffffff817ef9f2>] entry_SYSCALL_64_fastpath+0x16/0x75
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.024169] Code: ff eb ee 0f 1f 44 00 00 55 48 89 e5 41 55 41 54 53 49 89 f5 48 83 ec 08 48 8b bf 80 00 00 00 48 8b 5e 20 48 8b 47 08 48 8b 40 20 <48> 8b 80 28 01 00 00 48 85 c0 74 02 ff d0 48 85 db 74 61 4c 8b
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.024256] RIP [<ffffffffc0061f68>] drm_gem_map_detach+0x28/0xc0 [drm]
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.024278] RSP <ffff880248ea3a38>
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.024286] CR2: ffffffffc0d8a408
Oct 19 09:11:12 doug-Lenovo-IdeaPad-Y510P kernel: [ 49.029886] ---[ end trace b9c23c7583c780f2 ]---
ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: nvidia-prime 0.8.1
ProcVersionSignature: Ubuntu 4.2.0-16.19-generic 4.2.3
Uname: Linux 4.2.0-16-generic x86_64
ApportVersion: 2.19.1-0ubuntu2
Architecture: amd64
CurrentDesktop: Unity
Date: Mon Oct 19 09:23:06 2015
InstallationDate: Installed on 2015-09-28 (20 days ago)
InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Alpha amd64 (20150928)
SourcePackage: nvidia-prime
UpgradeStatus: No upgrade log present (probably fresh install)
Doesn't happen with modesetting so currently not an issue