Removing module failure

[zaufi]

Distribution (run cat /etc/os-release):

Gentoo.

Issue/Bug Description: Removing the module w/ rmmod system76 leads to failures:

[18939.625869] system76: Found NVIDIA audio device 0000:01:00.1
[18939.653698] iommu: Removing device  from group 1
[18939.653701] ------------[ cut here ]------------
[18939.653702] kernfs: can not remove 'iommu_group', no directory
[18939.653711] WARNING: CPU: 4 PID: 14991 at fs/kernfs/dir.c:1481 kernfs_remove_by_name_ns+0x73/0x80
[18939.653712] Modules linked in: veth system76(OE-) ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 xt_addrtype iptable_filter ip_tables xt_conntrack x_tables nf_nat nf_conntrack br_netfilter bridge stp llc ccm btusb btrtl btbcm btintel bluetooth ecdh_generic arc4 iwlmvm mac80211 iwlwifi snd_hda_codec_hdmi cfg80211 snd_hda_codec_realtek snd_hda_codec_generic x86_pkg_temp_thermal crct10dif_pclmul crc32_pclmul ghash_clmulni_intel pcbc snd_hda_intel iTCO_wdt snd_hda_codec iTCO_vendor_support aesni_intel aes_x86_64 crypto_simd tpm_crb snd_hwdep snd_hda_core glue_helper nvidia_drm(POE) cryptd nvidia_modeset(POE) intel_cstate snd_pcm psmouse nvidia(POE) snd_timer input_leds intel_rapl_perf serio_raw snd i2c_i801 intel_pch_thermal soundcore tpm_tis tpm_tis_core
[18939.653736]  acpi_pad vboxpci(OE) vboxnetadp(OE) vboxnetflt(OE) vboxdrv(OE) vboxguest vboxvideo(C) ttm coretemp intel_lpss_pci intel_lpss_acpi intel_lpss lpc_sch lpc_ich
[18939.653743] CPU: 4 PID: 14991 Comm: rmmod Tainted: P         C OE    4.16.16-gentoo-z2 #1
[18939.653743] Hardware name:  System76  Oryx Pro/ Oryx Pro, BIOS 1.05.02dRSA2 02/20/2017
[18939.653745] RIP: 0010:kernfs_remove_by_name_ns+0x73/0x80
[18939.653746] RSP: 0018:ffffaf618ad5fc80 EFLAGS: 00010282
[18939.653747] RAX: 0000000000000000 RBX: ffffa0a0a2796a00 RCX: 0000000000000006
[18939.653748] RDX: 0000000000000007 RSI: 0000000000000082 RDI: ffffa0a0c69155d0
[18939.653749] RBP: ffffffff8aac1c44 R08: 0000000000000005 R09: 0000000000000838
[18939.653749] R10: ffffaf618ad5fca0 R11: ffffffff8b21678d R12: ffffa0a0a206c358
[18939.653750] R13: ffffa0a0a206c300 R14: ffffa0a0a275a0a0 R15: 0000000000000000
[18939.653751] FS:  00007fad4df2fb80(0000) GS:ffffa0a0c6900000(0000) knlGS:0000000000000000
[18939.653752] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[18939.653753] CR2: 00005563858eea40 CR3: 00000002761af005 CR4: 00000000003606e0
[18939.653753] Call Trace:
[18939.653758]  iommu_group_remove_device+0xcf/0x190
[18939.653760]  intel_iommu_remove_device+0x3d/0x70
[18939.653762]  iommu_bus_notifier+0xbb/0xf0
[18939.653764]  notifier_call_chain+0x45/0x70
[18939.653766]  __blocking_notifier_call_chain+0x41/0x60
[18939.653768]  device_del+0x22a/0x310
[18939.653770]  pci_remove_bus_device+0x6e/0xf0
[18939.653773]  s76_remove+0x20f/0x260 [system76]
[18939.653775]  platform_drv_remove+0x22/0x40
[18939.653777]  device_release_driver_internal+0x154/0x220
[18939.653779]  bus_remove_device+0xe2/0x150
[18939.653780]  device_del+0x136/0x310
[18939.653781]  platform_device_del+0x23/0x80
[18939.653782]  platform_device_unregister+0xe/0x20
[18939.653784]  s76_exit+0xc/0x6e2 [system76]
[18939.653786]  SyS_delete_module+0x1d9/0x2a0
[18939.653788]  ? exit_to_usermode_loop+0x7b/0x90
[18939.653789]  do_syscall_64+0x5a/0x100
[18939.653791]  entry_SYSCALL_64_after_hwframe+0x3d/0xa2
[18939.653793] RIP: 0033:0x7fad4d650ff7
[18939.653793] RSP: 002b:00007ffe6b2c3138 EFLAGS: 00000202 ORIG_RAX: 00000000000000b0
[18939.653794] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fad4d650ff7
[18939.653795] RDX: 000000000000000a RSI: 0000000000000800 RDI: 0000000001eef7c8
[18939.653796] RBP: 0000000001eef760 R08: 0000000000000000 R09: 1999999999999999
[18939.653796] R10: 00000000000008d9 R11: 0000000000000202 R12: 00007ffe6b2c4c9f
[18939.653797] R13: 0000000000000000 R14: 0000000001eef760 R15: 0000000001eef260
[18939.653798] Code: 5f 00 31 c0 5b 5d 41 5c c3 48 c7 c7 40 01 c9 8a e8 e3 0a 5f 00 b8 fe ff ff ff 5b 5d 41 5c c3 48 c7 c7 f0 93 a8 8a e8 bd f1 dc ff <0f> 0b b8 fe ff ff ff eb d0 0f 1f 40 00 0f 1f 44 00 00 48 83 7f 
[18939.653814] ---[ end trace b1cde3b88e132714 ]---
[18939.653815] ------------[ cut here ]------------
[18939.653816] kernfs: can not remove 'iommu', no directory
[18939.653819] WARNING: CPU: 4 PID: 14991 at fs/kernfs/dir.c:1481 kernfs_remove_by_name_ns+0x73/0x80
[18939.653820] Modules linked in: veth system76(OE-) ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 xt_addrtype iptable_filter ip_tables xt_conntrack x_tables nf_nat nf_conntrack br_netfilter bridge stp llc ccm btusb btrtl btbcm btintel bluetooth ecdh_generic arc4 iwlmvm mac80211 iwlwifi snd_hda_codec_hdmi cfg80211 snd_hda_codec_realtek snd_hda_codec_generic x86_pkg_temp_thermal crct10dif_pclmul crc32_pclmul ghash_clmulni_intel pcbc snd_hda_intel iTCO_wdt snd_hda_codec iTCO_vendor_support aesni_intel aes_x86_64 crypto_simd tpm_crb snd_hwdep snd_hda_core glue_helper nvidia_drm(POE) cryptd nvidia_modeset(POE) intel_cstate snd_pcm psmouse nvidia(POE) snd_timer input_leds intel_rapl_perf serio_raw snd i2c_i801 intel_pch_thermal soundcore tpm_tis tpm_tis_core
[18939.653838]  acpi_pad vboxpci(OE) vboxnetadp(OE) vboxnetflt(OE) vboxdrv(OE) vboxguest vboxvideo(C) ttm coretemp intel_lpss_pci intel_lpss_acpi intel_lpss lpc_sch lpc_ich
[18939.653844] CPU: 4 PID: 14991 Comm: rmmod Tainted: P        WC OE    4.16.16-gentoo-z2 #1
[18939.653845] Hardware name:  System76  Oryx Pro/ Oryx Pro, BIOS 1.05.02dRSA2 02/20/2017
[18939.653846] RIP: 0010:kernfs_remove_by_name_ns+0x73/0x80
[18939.653847] RSP: 0018:ffffaf618ad5fc98 EFLAGS: 00010282
[18939.653848] RAX: 0000000000000000 RBX: ffffa0a0a61200f8 RCX: 0000000000000006
[18939.653849] RDX: 0000000000000007 RSI: 0000000000000092 RDI: ffffa0a0c69155d0
[18939.653850] RBP: ffffffff8aac2fbd R08: 0000000000000005 R09: 0000000000000866
[18939.653851] R10: ffffaf618ad5fbe0 R11: ffffffff8b21678d R12: ffffffff8acc4c60
[18939.653852] R13: 0000000000000003 R14: ffffa0a0a275a0a0 R15: 0000000000000000
[18939.653853] FS:  00007fad4df2fb80(0000) GS:ffffa0a0c6900000(0000) knlGS:0000000000000000
[18939.653854] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[18939.653855] CR2: 00005563858eea40 CR3: 00000002761af005 CR4: 00000000003606e0
[18939.653855] Call Trace:
[18939.653857]  iommu_device_unlink+0x2b/0x60
[18939.653859]  intel_iommu_remove_device+0x4c/0x70
[18939.653861]  iommu_bus_notifier+0xbb/0xf0
[18939.653863]  notifier_call_chain+0x45/0x70
[18939.653864]  __blocking_notifier_call_chain+0x41/0x60
[18939.653866]  device_del+0x22a/0x310
[18939.653868]  pci_remove_bus_device+0x6e/0xf0
[18939.653870]  s76_remove+0x20f/0x260 [system76]
[18939.653871]  platform_drv_remove+0x22/0x40
[18939.653873]  device_release_driver_internal+0x154/0x220
[18939.653875]  bus_remove_device+0xe2/0x150
[18939.653876]  device_del+0x136/0x310
[18939.653878]  platform_device_del+0x23/0x80
[18939.653879]  platform_device_unregister+0xe/0x20
[18939.653880]  s76_exit+0xc/0x6e2 [system76]
[18939.653882]  SyS_delete_module+0x1d9/0x2a0
[18939.653883]  ? exit_to_usermode_loop+0x7b/0x90
[18939.653884]  do_syscall_64+0x5a/0x100
[18939.653886]  entry_SYSCALL_64_after_hwframe+0x3d/0xa2
[18939.653887] RIP: 0033:0x7fad4d650ff7
[18939.653887] RSP: 002b:00007ffe6b2c3138 EFLAGS: 00000202 ORIG_RAX: 00000000000000b0
[18939.653888] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fad4d650ff7
[18939.653889] RDX: 000000000000000a RSI: 0000000000000800 RDI: 0000000001eef7c8
[18939.653890] RBP: 0000000001eef760 R08: 0000000000000000 R09: 1999999999999999
[18939.653890] R10: 00000000000008d9 R11: 0000000000000202 R12: 00007ffe6b2c4c9f
[18939.653891] R13: 0000000000000000 R14: 0000000001eef760 R15: 0000000001eef260
[18939.653892] Code: 5f 00 31 c0 5b 5d 41 5c c3 48 c7 c7 40 01 c9 8a e8 e3 0a 5f 00 b8 fe ff ff ff 5b 5d 41 5c c3 48 c7 c7 f0 93 a8 8a e8 bd f1 dc ff <0f> 0b b8 fe ff ff ff eb d0 0f 1f 40 00 0f 1f 44 00 00 48 83 7f 
[18939.653908] ---[ end trace b1cde3b88e132715 ]---
[18939.653935] BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
[18939.653937] IP: pci_remove_bus_device+0x89/0xf0
[18939.653937] PGD 34db46067 P4D 34db46067 PUD 1b9bc5067 PMD 0 
[18939.653952] Oops: 0002 [#1] PREEMPT SMP
[18939.653953] Modules linked in: veth system76(OE-) ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 xt_addrtype iptable_filter ip_tables xt_conntrack x_tables nf_nat nf_conntrack br_netfilter bridge stp llc ccm btusb btrtl btbcm btintel bluetooth ecdh_generic arc4 iwlmvm mac80211 iwlwifi snd_hda_codec_hdmi cfg80211 snd_hda_codec_realtek snd_hda_codec_generic x86_pkg_temp_thermal crct10dif_pclmul crc32_pclmul ghash_clmulni_intel pcbc snd_hda_intel iTCO_wdt snd_hda_codec iTCO_vendor_support aesni_intel aes_x86_64 crypto_simd tpm_crb snd_hwdep snd_hda_core glue_helper nvidia_drm(POE) cryptd nvidia_modeset(POE) intel_cstate snd_pcm psmouse nvidia(POE) snd_timer input_leds intel_rapl_perf serio_raw snd i2c_i801 intel_pch_thermal soundcore tpm_tis tpm_tis_core
[18939.653981]  acpi_pad vboxpci(OE) vboxnetadp(OE) vboxnetflt(OE) vboxdrv(OE) vboxguest vboxvideo(C) ttm coretemp intel_lpss_pci intel_lpss_acpi intel_lpss lpc_sch lpc_ich
[18939.653985] CPU: 4 PID: 14991 Comm: rmmod Tainted: P        WC OE    4.16.16-gentoo-z2 #1
[18939.653986] Hardware name:  System76  Oryx Pro/ Oryx Pro, BIOS 1.05.02dRSA2 02/20/2017
[18939.653987] RIP: 0010:pci_remove_bus_device+0x89/0xf0
[18939.653988] RSP: 0018:ffffaf618ad5fdc8 EFLAGS: 00010246
[18939.653989] RAX: ffffa0a0a2759000 RBX: ffffa0a0a275a378 RCX: ffffa0a0a275a0b8
[18939.653989] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8acb45e0
[18939.653990] RBP: ffffa0a0a275a000 R08: 0000000000024440 R09: ffffffff8a26aac3
[18939.653991] R10: ffffe2405e709a00 R11: 0000000000000000 R12: ffffa0a0a275a0a0
[18939.653991] R13: 0000000000000000 R14: 0000000000000060 R15: 0000000000000000
[18939.653992] FS:  00007fad4df2fb80(0000) GS:ffffa0a0c6900000(0000) knlGS:0000000000000000
[18939.653993] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[18939.653993] CR2: 0000000000000008 CR3: 00000002761af005 CR4: 00000000003606e0
[18939.653994] Call Trace:
[18939.653996]  s76_remove+0x20f/0x260 [system76]
[18939.653997]  platform_drv_remove+0x22/0x40
[18939.653999]  device_release_driver_internal+0x154/0x220
[18939.654000]  bus_remove_device+0xe2/0x150
[18939.654001]  device_del+0x136/0x310
[18939.654003]  platform_device_del+0x23/0x80
[18939.654004]  platform_device_unregister+0xe/0x20
[18939.654005]  s76_exit+0xc/0x6e2 [system76]
[18939.654006]  SyS_delete_module+0x1d9/0x2a0
[18939.654007]  ? exit_to_usermode_loop+0x7b/0x90
[18939.654008]  do_syscall_64+0x5a/0x100
[18939.654010]  entry_SYSCALL_64_after_hwframe+0x3d/0xa2
[18939.654011] RIP: 0033:0x7fad4d650ff7
[18939.654011] RSP: 002b:00007ffe6b2c3138 EFLAGS: 00000202 ORIG_RAX: 00000000000000b0
[18939.654012] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fad4d650ff7
[18939.654013] RDX: 000000000000000a RSI: 0000000000000800 RDI: 0000000001eef7c8
[18939.654014] RBP: 0000000001eef760 R08: 0000000000000000 R09: 1999999999999999
[18939.654014] R10: 00000000000008d9 R11: 0000000000000202 R12: 00007ffe6b2c4c9f
[18939.654015] R13: 0000000000000000 R14: 0000000001eef760 R15: 0000000001eef260
[18939.654016] Code: 00 48 8d 9d 78 03 00 00 4c 89 e7 e8 d2 ec 10 00 48 c7 c7 e0 45 cb 8a e8 96 a0 39 00 48 8b 55 00 48 8b 45 08 48 c7 c7 e0 45 cb 8a <48> 89 42 08 48 89 10 48 b8 00 01 00 00 00 00 ad de 48 89 45 00 
[18939.654032] RIP: pci_remove_bus_device+0x89/0xf0 RSP: ffffaf618ad5fdc8
[18939.654033] CR2: 0000000000000008
[18939.654034] ---[ end trace b1cde3b88e132716 ]---