[solved] linux kernel driver crashes (with traceback) on 3.17

I’ve updated my kernel to 3.17 and looks like the nvidia kernel module fails to load:

kernel: bbswitch: enabling discrete graphics
kernel: ------------[ cut here ]------------
kernel: WARNING: CPU: 2 PID: 7534 at fs/proc/generic.c:315 proc_register+0xd4/0x104()
kernel: proc_dir_entry 'driver/nvidia' already registered
kernel: Modules linked in: nvidia(PO+) bbswitch(O) ipv6 x86_pkg_temp_thermal coretemp kvm_intel kvm uas snd_hda_codec_hdmi mxm_wmi joydev snd_hda_codec_realtek snd_hda_codec_generic snd_hda_intel wmi rtc_cmos acpi_cpufreq snd_hda_controller snd_hda_codec pcspkr ac snd_hwdep snd_pcm snd_timer snd i2c_i801 xts gf128mul aes_x86_64 cbc sha256_generic libiscsi scsi_transport_iscsi fuse nfs lockd sunrpc multipath linear raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor xor async_tx raid6_pq raid1 raid0 dm_snapshot dm_bufio dm_crypt dm_mirror dm_region_hash dm_log dm_mod hid_sunplus hid_sony hid_samsung hid_pl hid_petalynx hid_gyration sl811_hcd usbhid xhci_hcd ohci_hcd uhci_hcd usb_storage ehci_pci ehci_hcd aic94xx libsas lpfc crc_t10dif crct10dif_common qla2xxx megaraid_sas megaraid_mbox megaraid_mm megaraid aacraid sx8 DAC960 3w_9xxx 3w_xxxx mptsas scsi_transport_sas mptfc scsi_transport_fc mptspi mptscsih mptbase atp870u dc395x qla1280 dmx3191d sym53c8xx gdth advansys initio BusLogic arcmsr aic7xxx aic79xx scsi_transport_spi sg pdc_adma sata_inic162x ata_piix ahci libahci sata_qstor sata_vsc sata_uli sata_sis sata_sx4 sata_nv sata_via sata_svw sata_sil24 sata_sil sata_promise pata_sl82c105 pata_via pata_jmicron pata_marvell pata_sis pata_netcell pata_pdc202xx_old pata_triflex pata_atiixp pata_opti pata_amd pata_ali pata_it8213 pata_pcmcia pcmcia pcmcia_core pata_ns87415 pata_ns87410 pata_serverworks pata_artop pata_it821x pata_optidma pata_hpt3x2n pata_hpt3x3 pata_hpt37x pata_hpt366 pata_cmd64x pata_efar pata_rz1000 pata_sil680 pata_radisys pata_pdc2027x pata_mpiix libata [last unloaded: nvidia]
kernel: [<ffffffff8103772b>] warn_slowpath_fmt+0x43/0x4b
kernel: [<ffffffff81051adf>] ? preempt_count_add+0x7b/0x8e
kernel: [<ffffffff81147c60>] proc_register+0xd4/0x104
kernel: [<ffffffff81147d6c>] proc_mkdir_data+0x4c/0x63
kernel: [<ffffffff81147d91>] proc_mkdir_mode+0xe/0x10
kernel: [<ffffffffa1ca012e>] nv_register_procfs+0x3a/0x19d [nvidia]
kernel: [<ffffffffa1313260>] nvidia_init_module+0x260/0x72e [nvidia]
kernel: [<ffffffffa1313743>] ? nv_drm_init+0x15/0x15 [nvidia]
kernel: [<ffffffffa13137c8>] nvidia_frontend_init_module+0x85/0xb6 [nvidia]
kernel: [<ffffffff8100030c>] do_one_initcall+0xe9/0x16d
kernel: [<ffffffff810dbe50>] ? __vunmap+0xa8/0xb0
kernel: [<ffffffff81089c74>] load_module+0x17fb/0x1d31
kernel: [<ffffffff8108747e>] ? copy_module_from_fd+0x89/0xea
kernel: [<ffffffff8108a29a>] SyS_finit_module+0x59/0x66
kernel: [<ffffffff8108a29a>] ? SyS_finit_module+0x59/0x66
kernel: [<ffffffff81565892>] system_call_fastpath+0x16/0x1b
kernel: ---[ end trace 59a00e2eac3daef7 ]---

Distro: gentoo
nvidia driver: x11-drivers/nvidia-drivers-343.22-r2
Kernel: 3.17.1-gentoo-r1
gpu: 01:00.0 VGA compatible controller: NVIDIA Corporation GF108M [GeForce GT 550M] (rev ff)

(Repost from https://forums.geforce.com/default/topic/785172.)

looks like that my kernel configuration was messed up somehow; works fine after reboot