[Linux 5.12.3][nvidia 465.27] llvmpipe used instead of nvidia, driver race condition

username@nihil ~ $ nvidia-smi
Mon May 17 04:08:00 2021       
+-----------------------------------------------------------------------------+
| NVIDIA-SMI 465.27       Driver Version: 465.27       CUDA Version: 11.3     |
|-------------------------------+----------------------+----------------------+
| GPU  Name        Persistence-M| Bus-Id        Disp.A | Volatile Uncorr. ECC |
| Fan  Temp  Perf  Pwr:Usage/Cap|         Memory-Usage | GPU-Util  Compute M. |
|                               |                      |               MIG M. |
|===============================+======================+======================|
|   0  NVIDIA GeForce ...  Off  | 00000000:1C:00.0  On |                  N/A |
|  0%   60C    P0    42W / 230W |    672MiB /  8116MiB |     11%      Default |
|                               |                      |                  N/A |
+-------------------------------+----------------------+----------------------+
                                                                               
+-----------------------------------------------------------------------------+
| Processes:                                                                  |
|  GPU   GI   CI        PID   Type   Process name                  GPU Memory |
|        ID   ID                                                   Usage      |
|=============================================================================|
|    0   N/A  N/A       549      G   /usr/lib/Xorg                     470MiB |
+-----------------------------------------------------------------------------+

username@nihil ~ $ glxinfo -B
name of display: :0
display: :0 screen: 0
direct rendering: Yes
Extended renderer info (GLX_MESA_query_renderer):
Vendor: Mesa/X.org (0xffffffff)
Device: llvmpipe (LLVM 11.1.0, 256 bits) (0xffffffff)
Version: 21.1.0
Accelerated: no
Video memory: 16013MB
Unified memory: no
Preferred profile: core (0x1)
Max core profile version: 4.5
Max compat profile version: 3.1
Max GLES1 profile version: 1.1
Max GLES[23] profile version: 3.2
OpenGL vendor string: Mesa/X.org
OpenGL renderer string: llvmpipe (LLVM 11.1.0, 256 bits)
OpenGL core profile version string: 4.5 (Core Profile) Mesa 21.1.0
OpenGL core profile shading language version string: 4.50
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile

OpenGL version string: 3.1 Mesa 21.1.0
OpenGL shading language version string: 1.40
OpenGL context flags: (none)

OpenGL ES profile version string: OpenGL ES 3.2 Mesa 21.1.0
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.20

username@nihil ~ $ inxi -G
zsh: correct 'inxi' to '_inxi' [nyae]? n
Graphics:  Device-1: NVIDIA GP104 [GeForce GTX 1070] driver: nvidia v: 465.27 
           Display: x11 server: X.Org 1.20.11 driver: loaded: modesetting failed: nvidia resolution: 1: 3840x2160~60Hz 
           2: 3840x2160~60Hz 3: 3840x2160~60Hz 
           OpenGL: renderer: llvmpipe (LLVM 11.1.0 256 bits) v: 4.5 Mesa 21.1.0 

More pertinently we find this in dmesg:

[  +0.729136] [drm] Initialized nvidia-drm 0.0.0 20160202 for 0000:1c:00.0 on minor 0
    [  +0.855901] ------------[ cut here ]------------
    [  +0.000005] WARNING: CPU: 15 PID: 549 at /build/nvidia/src/nvidia/465.27/build/nvidia-drm/nvidia-drm-drv.c:568 nv_drm_master_set+0x22/0x30 [nvidia_drm]
    [  +0.000016] Modules linked in: nvidia_drm(POE) nvidia_modeset(POE) nvidia(POE) cfg80211 snd_usb_audio snd_usbmidi_lib intel_rapl_msr rfkill snd_rawmidi snd_seq_device intel_rapl_common joydev mousedev mc 8021q snd_hda_codec_realtek garp edac_mce_amd mrp snd_hda_codec_generic stp snd_hda_codec_hdmi llc ledtrig_audio kvm_amd ccp snd_hda_intel rng_core snd_intel_dspcfg snd_intel_sdw_acpi snd_hda_codec kvm snd_hda_core nls_iso8859_1 snd_hwdep vfat irqbypass fat snd_pcm usbhid crct10dif_pclmul crc32_pclmul wmi_bmof mxm_wmi drm_kms_helper ghash_clmulni_intel snd_timer igb aesni_intel cec snd crypto_simd syscopyarea cryptd sysfillrect sp5100_tco i2c_algo_bit sysimgblt rapl k10temp pcspkr i2c_piix4 fb_sys_fops soundcore dca wmi gpio_amdpt pinctrl_amd gpio_generic mac_hid acpi_cpufreq drm sg fuse agpgart bpf_preload ip_tables x_tables ext4 crc32c_generic crc16 mbcache jbd2 xhci_pci crc32c_intel xhci_pci_renesas
    [  +0.000120] CPU: 15 PID: 549 Comm: Xorg Tainted: P           OE     5.12.3-arch1-1 #1
    [  +0.000005] Hardware name: Micro-Star International Co., Ltd. MS-7B78/X470 GAMING PRO CARBON (MS-7B78), BIOS 2.80 03/06/2019
    [  +0.000003] RIP: 0010:nv_drm_master_set+0x22/0x30 [nvidia_drm]
    [  +0.000014] Code: e4 ef 4f c8 0f 1f 40 00 0f 1f 44 00 00 48 8b 47 38 48 8b 78 20 48 8b 05 9c 5c 00 00 48 8b 40 28 e8 93 9c 87 c8 84 c0 74 01 c3 <0f> 0b c3 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 80 3d 7c
    [  +0.000005] RSP: 0018:ffffc11c01a87bc8 EFLAGS: 00010246
    [  +0.000005] RAX: 0000000000000000 RBX: ffff9e884accb800 RCX: 0000000000000008
    [  +0.000004] RDX: ffffffffc0f5ee58 RSI: 0000000000000286 RDI: ffffffffc0f5ee20
    [  +0.000003] RBP: ffff9e884553c540 R08: 0000000000000008 R09: ffffc11c01a87bb0
    [  +0.000002] R10: 0000000000000000 R11: 0000000000000000 R12: ffff9e8856e67000
    [  +0.000003] R13: 0000000000000000 R14: ffff9e8856e67000 R15: 000000004559fca8
    [  +0.000003] FS:  00007fadaa6fc940(0000) GS:ffff9e8b4edc0000(0000) knlGS:0000000000000000
    [  +0.000004] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    [  +0.000007] CR2: 000056150d777348 CR3: 0000000117950000 CR4: 00000000003506e0
    [  +0.000004] Call Trace:
    [  +0.000003]  drm_new_set_master+0x7a/0x100 [drm]
    [  +0.000050]  drm_master_open+0x68/0x90 [drm]
    [  +0.000047]  drm_open+0xf5/0x240 [drm]
    [  +0.000049]  drm_stub_open+0xab/0x130 [drm]
    [  +0.000051]  chrdev_open+0xca/0x240
    [  +0.000007]  ? cdev_device_add+0x90/0x90
    [  +0.000004]  do_dentry_open+0x14e/0x380
    [  +0.000005]  path_openat+0xb92/0x1050
    [  +0.000007]  ? inotify_handle_inode_event+0x1c0/0x1f0
    [  +0.000009]  do_filp_open+0x9c/0x140
    [  +0.000007]  do_sys_openat2+0xb1/0x160
    [  +0.000005]  __x64_sys_openat+0x54/0x90
    [  +0.000005]  do_syscall_64+0x33/0x40
    [  +0.000006]  entry_SYSCALL_64_after_hwframe+0x44/0xae
    [  +0.000006] RIP: 0033:0x7fadab0fae24
    [  +0.000004] Code: 24 20 eb 8f 66 90 44 89 54 24 0c e8 c6 53 f9 ff 44 8b 54 24 0c 44 89 e2 48 89 ee 41 89 c0 bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 77 34 44 89 c7 89 44 24 0c e8 18 54 f9 ff 8b 44
    [  +0.000005] RSP: 002b:00007fff3c0c44a0 EFLAGS: 00000293 ORIG_RAX: 0000000000000101
    [  +0.000004] RAX: ffffffffffffffda RBX: 00000000ffffffff RCX: 00007fadab0fae24
    [  +0.000002] RDX: 0000000000080002 RSI: 000056150d601120 RDI: 00000000ffffff9c
    [  +0.000003] RBP: 000056150d601120 R08: 0000000000000000 R09: 0000000000000000
    [  +0.000002] R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000080002
    [  +0.000003] R13: 000056150d601120 R14: 000056150d601120 R15: 0000000000000000
    [  +0.000005] ---[ end trace ba55af76f69314c0 ]---
    [  +0.004191] ------------[ cut here ]------------
    [  +0.000004] WARNING: CPU: 15 PID: 549 at /build/nvidia/src/nvidia/465.27/build/nvidia-drm/nvidia-drm-drv.c:568 nv_drm_master_set+0x22/0x30 [nvidia_drm]
    [  +0.000014] Modules linked in: nvidia_drm(POE) nvidia_modeset(POE) nvidia(POE) cfg80211 snd_usb_audio snd_usbmidi_lib intel_rapl_msr rfkill snd_rawmidi snd_seq_device intel_rapl_common joydev mousedev mc 8021q snd_hda_codec_realtek garp edac_mce_amd mrp snd_hda_codec_generic stp snd_hda_codec_hdmi llc ledtrig_audio kvm_amd ccp snd_hda_intel rng_core snd_intel_dspcfg snd_intel_sdw_acpi snd_hda_codec kvm snd_hda_core nls_iso8859_1 snd_hwdep vfat irqbypass fat snd_pcm usbhid crct10dif_pclmul crc32_pclmul wmi_bmof mxm_wmi drm_kms_helper ghash_clmulni_intel snd_timer igb aesni_intel cec snd crypto_simd syscopyarea cryptd sysfillrect sp5100_tco i2c_algo_bit sysimgblt rapl k10temp pcspkr i2c_piix4 fb_sys_fops soundcore dca wmi gpio_amdpt pinctrl_amd gpio_generic mac_hid acpi_cpufreq drm sg fuse agpgart bpf_preload ip_tables x_tables ext4 crc32c_generic crc16 mbcache jbd2 xhci_pci crc32c_intel xhci_pci_renesas
    [  +0.000088] CPU: 15 PID: 549 Comm: Xorg Tainted: P        W  OE     5.12.3-arch1-1 #1
    [  +0.000005] Hardware name: Micro-Star International Co., Ltd. MS-7B78/X470 GAMING PRO CARBON (MS-7B78), BIOS 2.80 03/06/2019
    [  +0.000002] RIP: 0010:nv_drm_master_set+0x22/0x30 [nvidia_drm]
    [  +0.000009] Code: e4 ef 4f c8 0f 1f 40 00 0f 1f 44 00 00 48 8b 47 38 48 8b 78 20 48 8b 05 9c 5c 00 00 48 8b 40 28 e8 93 9c 87 c8 84 c0 74 01 c3 <0f> 0b c3 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 80 3d 7c
    [  +0.000005] RSP: 0018:ffffc11c01a87bc8 EFLAGS: 00010246
    [  +0.000004] RAX: 0000000000000000 RBX: ffff9e884accb800 RCX: 0000000000000008
    [  +0.000002] RDX: ffffffffc0f5ee58 RSI: 0000000000000286 RDI: ffffffffc0f5ee20
    [  +0.000003] RBP: ffff9e884553c540 R08: 0000000000000008 R09: ffffc11c01a87bb0
    [  +0.000002] R10: 0000000000000000 R11: 0000000000000000 R12: ffff9e8856e67000
    [  +0.000002] R13: 0000000000000000 R14: ffff9e8856e67000 R15: 000000004559fca8
    [  +0.000003] FS:  00007fadaa6fc940(0000) GS:ffff9e8b4edc0000(0000) knlGS:0000000000000000
    [  +0.000003] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    [  +0.000003] CR2: 000056150cf793a8 CR3: 0000000117950000 CR4: 00000000003506e0
    [  +0.000004] Call Trace:
    [  +0.000003]  drm_new_set_master+0x7a/0x100 [drm]
    [  +0.000049]  drm_master_open+0x68/0x90 [drm]
    [  +0.000046]  drm_open+0xf5/0x240 [drm]
    [  +0.000048]  drm_stub_open+0xab/0x130 [drm]
    [  +0.000050]  chrdev_open+0xca/0x240
    [  +0.000005]  ? cdev_device_add+0x90/0x90
    [  +0.000004]  do_dentry_open+0x14e/0x380
    [  +0.000005]  path_openat+0xb92/0x1050
    [  +0.000006]  ? inotify_handle_inode_event+0x1c0/0x1f0
    [  +0.000008]  do_filp_open+0x9c/0x140
    [  +0.000007]  do_sys_openat2+0xb1/0x160
    [  +0.000005]  __x64_sys_openat+0x54/0x90
    [  +0.000005]  do_syscall_64+0x33/0x40
    [  +0.000006]  entry_SYSCALL_64_after_hwframe+0x44/0xae
    [  +0.000004] RIP: 0033:0x7fadab0fae24
    [  +0.000004] Code: 24 20 eb 8f 66 90 44 89 54 24 0c e8 c6 53 f9 ff 44 8b 54 24 0c 44 89 e2 48 89 ee 41 89 c0 bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 77 34 44 89 c7 89 44 24 0c e8 18 54 f9 ff 8b 44
    [  +0.000004] RSP: 002b:00007fff3c0c4470 EFLAGS: 00000293 ORIG_RAX: 0000000000000101
    [  +0.000004] RAX: ffffffffffffffda RBX: 000056150d6b1de0 RCX: 00007fadab0fae24
    [  +0.000003] RDX: 0000000000080002 RSI: 000056150d601120 RDI: 00000000ffffff9c
    [  +0.000002] RBP: 000056150d601120 R08: 0000000000000000 R09: 00007fadab1cca60
    [  +0.000002] R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000080002
    [  +0.000002] R13: 000056150d601120 R14: 000056150d601120 R15: 0000000000000001
    [  +0.000006] ---[ end trace ba55af76f69314c1 ]---
    [  +0.000134] ------------[ cut here ]------------
    [  +0.000002] WARNING: CPU: 15 PID: 549 at /build/nvidia/src/nvidia/465.27/build/nvidia-drm/nvidia-drm-drv.c:568 nv_drm_master_set+0x22/0x30 [nvidia_drm]
    [  +0.000012] Modules linked in: nvidia_drm(POE) nvidia_modeset(POE) nvidia(POE) cfg80211 snd_usb_audio snd_usbmidi_lib intel_rapl_msr rfkill snd_rawmidi snd_seq_device intel_rapl_common joydev mousedev mc 8021q snd_hda_codec_realtek garp edac_mce_amd mrp snd_hda_codec_generic stp snd_hda_codec_hdmi llc ledtrig_audio kvm_amd ccp snd_hda_intel rng_core snd_intel_dspcfg snd_intel_sdw_acpi snd_hda_codec kvm snd_hda_core nls_iso8859_1 snd_hwdep vfat irqbypass fat snd_pcm usbhid crct10dif_pclmul crc32_pclmul wmi_bmof mxm_wmi drm_kms_helper ghash_clmulni_intel snd_timer igb aesni_intel cec snd crypto_simd syscopyarea cryptd sysfillrect sp5100_tco i2c_algo_bit sysimgblt rapl k10temp pcspkr i2c_piix4 fb_sys_fops soundcore dca wmi gpio_amdpt pinctrl_amd gpio_generic mac_hid acpi_cpufreq drm sg fuse agpgart bpf_preload ip_tables x_tables ext4 crc32c_generic crc16 mbcache jbd2 xhci_pci crc32c_intel xhci_pci_renesas
    [  +0.000085] CPU: 15 PID: 549 Comm: Xorg Tainted: P        W  OE     5.12.3-arch1-1 #1
    [  +0.000004] Hardware name: Micro-Star International Co., Ltd. MS-7B78/X470 GAMING PRO CARBON (MS-7B78), BIOS 2.80 03/06/2019
    [  +0.000002] RIP: 0010:nv_drm_master_set+0x22/0x30 [nvidia_drm]
    [  +0.000008] Code: e4 ef 4f c8 0f 1f 40 00 0f 1f 44 00 00 48 8b 47 38 48 8b 78 20 48 8b 05 9c 5c 00 00 48 8b 40 28 e8 93 9c 87 c8 84 c0 74 01 c3 <0f> 0b c3 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 80 3d 7c
    [  +0.000004] RSP: 0018:ffffc11c01a87bc8 EFLAGS: 00010246
    [  +0.000004] RAX: 0000000000000000 RBX: ffff9e884accb800 RCX: 0000000000000008
    [  +0.000002] RDX: ffffffffc0f5ee58 RSI: 0000000000000286 RDI: ffffffffc0f5ee20
    [  +0.000002] RBP: ffff9e884553c540 R08: 0000000000000008 R09: ffffc11c01a87bb0
    [  +0.000002] R10: 0000000000000000 R11: 0000000000000000 R12: ffff9e8856e67000
    [  +0.000003] R13: 0000000000000000 R14: ffff9e8856e67000 R15: 000000004559fca8
    [  +0.000002] FS:  00007fadaa6fc940(0000) GS:ffff9e8b4edc0000(0000) knlGS:0000000000000000
    [  +0.000003] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    [  +0.000003] CR2: 000056150cf7e528 CR3: 0000000117950000 CR4: 00000000003506e0
    [  +0.000003] Call Trace:
    [  +0.000003]  drm_new_set_master+0x7a/0x100 [drm]
    [  +0.000047]  drm_master_open+0x68/0x90 [drm]
    [  +0.000047]  drm_open+0xf5/0x240 [drm]
    [  +0.000047]  drm_stub_open+0xab/0x130 [drm]
    [  +0.000050]  chrdev_open+0xca/0x240
    [  +0.000005]  ? cdev_device_add+0x90/0x90
    [  +0.000004]  do_dentry_open+0x14e/0x380
    [  +0.000004]  path_openat+0xb92/0x1050
    [  +0.000006]  ? inotify_handle_inode_event+0x1c0/0x1f0
    [  +0.000008]  do_filp_open+0x9c/0x140
    [  +0.000007]  do_sys_openat2+0xb1/0x160
    [  +0.000005]  __x64_sys_openat+0x54/0x90
    [  +0.000004]  do_syscall_64+0x33/0x40
    [  +0.000006]  entry_SYSCALL_64_after_hwframe+0x44/0xae
    [  +0.000004] RIP: 0033:0x7fadab0fae24
    [  +0.000004] Code: 24 20 eb 8f 66 90 44 89 54 24 0c e8 c6 53 f9 ff 44 8b 54 24 0c 44 89 e2 48 89 ee 41 89 c0 bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 77 34 44 89 c7 89 44 24 0c e8 18 54 f9 ff 8b 44
    [  +0.000004] RSP: 002b:00007fff3c0c42d0 EFLAGS: 00000293 ORIG_RAX: 0000000000000101
    [  +0.000004] RAX: ffffffffffffffda RBX: 000056150d7374c0 RCX: 00007fadab0fae24
    [  +0.000002] RDX: 0000000000080002 RSI: 000056150d601120 RDI: 00000000ffffff9c
    [  +0.000002] RBP: 000056150d601120 R08: 0000000000000000 R09: 00007fadab1cca60
    [  +0.000002] R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000080002
    [  +0.000003] R13: 000056150d601120 R14: 0000000000000000 R15: 000056150d6b0930
    [  +0.000004] ---[ end trace ba55af76f69314c2 ]---
    [  +0.304966] igb 0000:18:00.0 enp24s0: igb: enp24s0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX
    [  +0.000334] IPv6: ADDRCONF(NETDEV_CHANGE): enp24s0: link becomes ready
    [  +0.289965] ------------[ cut here ]------------
    [  +0.000005] WARNING: CPU: 7 PID: 549 at /build/nvidia/src/nvidia/465.27/build/nvidia-drm/nvidia-drm-drv.c:568 nv_drm_master_set+0x22/0x30 [nvidia_drm]
    [  +0.000015] Modules linked in: nvidia_drm(POE) nvidia_modeset(POE) nvidia(POE) cfg80211 snd_usb_audio snd_usbmidi_lib intel_rapl_msr rfkill snd_rawmidi snd_seq_device intel_rapl_common joydev mousedev mc 8021q snd_hda_codec_realtek garp edac_mce_amd mrp snd_hda_codec_generic stp snd_hda_codec_hdmi llc ledtrig_audio kvm_amd ccp snd_hda_intel rng_core snd_intel_dspcfg snd_intel_sdw_acpi snd_hda_codec kvm snd_hda_core nls_iso8859_1 snd_hwdep vfat irqbypass fat snd_pcm usbhid crct10dif_pclmul crc32_pclmul wmi_bmof mxm_wmi drm_kms_helper ghash_clmulni_intel snd_timer igb aesni_intel cec snd crypto_simd syscopyarea cryptd sysfillrect sp5100_tco i2c_algo_bit sysimgblt rapl k10temp pcspkr i2c_piix4 fb_sys_fops soundcore dca wmi gpio_amdpt pinctrl_amd gpio_generic mac_hid acpi_cpufreq drm sg fuse agpgart bpf_preload ip_tables x_tables ext4 crc32c_generic crc16 mbcache jbd2 xhci_pci crc32c_intel xhci_pci_renesas
    [  +0.000091] CPU: 7 PID: 549 Comm: Xorg Tainted: P        W  OE     5.12.3-arch1-1 #1
    [  +0.000004] Hardware name: Micro-Star International Co., Ltd. MS-7B78/X470 GAMING PRO CARBON (MS-7B78), BIOS 2.80 03/06/2019
    [  +0.000003] RIP: 0010:nv_drm_master_set+0x22/0x30 [nvidia_drm]
    [  +0.000008] Code: e4 ef 4f c8 0f 1f 40 00 0f 1f 44 00 00 48 8b 47 38 48 8b 78 20 48 8b 05 9c 5c 00 00 48 8b 40 28 e8 93 9c 87 c8 84 c0 74 01 c3 <0f> 0b c3 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 80 3d 7c
    [  +0.000005] RSP: 0018:ffffc11c01a87bc8 EFLAGS: 00010246
    [  +0.000004] RAX: 0000000000000000 RBX: ffff9e886bdcec00 RCX: 0000000000000008
    [  +0.000003] RDX: ffffffffc0f5ee58 RSI: 0000000000000286 RDI: ffffffffc0f5ee20
    [  +0.000002] RBP: ffff9e8850ba72c0 R08: 0000000000000008 R09: ffffc11c01a87bb0
    [  +0.000002] R10: 0000000000000000 R11: 0000000000000000 R12: ffff9e8856e67000
    [  +0.000002] R13: 0000000000000000 R14: ffff9e8856e67000 R15: 000000004559fca8
    [  +0.000002] FS:  00007fadaa6fc940(0000) GS:ffff9e8b4ebc0000(0000) knlGS:0000000000000000
    [  +0.000004] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    [  +0.000002] CR2: 000056150d213334 CR3: 0000000117950000 CR4: 00000000003506e0
    [  +0.000003] Call Trace:
    [  +0.000003]  drm_new_set_master+0x7a/0x100 [drm]
    [  +0.000043]  drm_master_open+0x68/0x90 [drm]
    [  +0.000039]  drm_open+0xf5/0x240 [drm]
    [  +0.000040]  drm_stub_open+0xab/0x130 [drm]
    [  +0.000042]  chrdev_open+0xca/0x240
    [  +0.000007]  ? cdev_device_add+0x90/0x90
    [  +0.000004]  do_dentry_open+0x14e/0x380
    [  +0.000005]  path_openat+0xb92/0x1050
    [  +0.000005]  ? inotify_handle_inode_event+0x1c0/0x1f0
    [  +0.000008]  do_filp_open+0x9c/0x140
    [  +0.000006]  do_sys_openat2+0xb1/0x160
    [  +0.000005]  __x64_sys_openat+0x54/0x90
    [  +0.000004]  do_syscall_64+0x33/0x40
    [  +0.000006]  entry_SYSCALL_64_after_hwframe+0x44/0xae
    [  +0.000005] RIP: 0033:0x7fadab0fae24
    [  +0.000004] Code: 24 20 eb 8f 66 90 44 89 54 24 0c e8 c6 53 f9 ff 44 8b 54 24 0c 44 89 e2 48 89 ee 41 89 c0 bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 77 34 44 89 c7 89 44 24 0c e8 18 54 f9 ff 8b 44
    [  +0.000003] RSP: 002b:00007fff3c0c3830 EFLAGS: 00000293 ORIG_RAX: 0000000000000101
    [  +0.000004] RAX: ffffffffffffffda RBX: 00000000ffffffff RCX: 00007fadab0fae24
    [  +0.000002] RDX: 0000000000080002 RSI: 000056150d630920 RDI: 00000000ffffff9c
    [  +0.000002] RBP: 000056150d630920 R08: 0000000000000000 R09: 0000000000000000
    [  +0.000002] R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000080002
    [  +0.000002] R13: 000056150d630920 R14: 000056150d630920 R15: 00007fff3c0c473c
    [  +0.000004] ---[ end trace ba55af76f69314c3 ]---
    [  +0.000343] ------------[ cut here ]------------
    [  +0.000002] WARNING: CPU: 7 PID: 549 at /build/nvidia/src/nvidia/465.27/build/nvidia-drm/nvidia-drm-drv.c:568 nv_drm_master_set+0x22/0x30 [nvidia_drm]
    [  +0.000011] Modules linked in: nvidia_drm(POE) nvidia_modeset(POE) nvidia(POE) cfg80211 snd_usb_audio snd_usbmidi_lib intel_rapl_msr rfkill snd_rawmidi snd_seq_device intel_rapl_common joydev mousedev mc 8021q snd_hda_codec_realtek garp edac_mce_amd mrp snd_hda_codec_generic stp snd_hda_codec_hdmi llc ledtrig_audio kvm_amd ccp snd_hda_intel rng_core snd_intel_dspcfg snd_intel_sdw_acpi snd_hda_codec kvm snd_hda_core nls_iso8859_1 snd_hwdep vfat irqbypass fat snd_pcm usbhid crct10dif_pclmul crc32_pclmul wmi_bmof mxm_wmi drm_kms_helper ghash_clmulni_intel snd_timer igb aesni_intel cec snd crypto_simd syscopyarea cryptd sysfillrect sp5100_tco i2c_algo_bit sysimgblt rapl k10temp pcspkr i2c_piix4 fb_sys_fops soundcore dca wmi gpio_amdpt pinctrl_amd gpio_generic mac_hid acpi_cpufreq drm sg fuse agpgart bpf_preload ip_tables x_tables ext4 crc32c_generic crc16 mbcache jbd2 xhci_pci crc32c_intel xhci_pci_renesas
    [  +0.000071] CPU: 7 PID: 549 Comm: Xorg Tainted: P        W  OE     5.12.3-arch1-1 #1
    [  +0.000003] Hardware name: Micro-Star International Co., Ltd. MS-7B78/X470 GAMING PRO CARBON (MS-7B78), BIOS 2.80 03/06/2019
    [  +0.000002] RIP: 0010:nv_drm_master_set+0x22/0x30 [nvidia_drm]
    [  +0.000007] Code: e4 ef 4f c8 0f 1f 40 00 0f 1f 44 00 00 48 8b 47 38 48 8b 78 20 48 8b 05 9c 5c 00 00 48 8b 40 28 e8 93 9c 87 c8 84 c0 74 01 c3 <0f> 0b c3 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 80 3d 7c
    [  +0.000004] RSP: 0018:ffffc11c01a87bc8 EFLAGS: 00010246
    [  +0.000003] RAX: 0000000000000000 RBX: ffff9e886bdcec00 RCX: 0000000000000008
    [  +0.000002] RDX: ffffffffc0f5ee58 RSI: 0000000000000286 RDI: ffffffffc0f5ee20
    [  +0.000002] RBP: ffff9e8850ba72c0 R08: 0000000000000008 R09: ffffc11c01a87bb0
    [  +0.000001] R10: 0000000000000000 R11: 0000000000000000 R12: ffff9e8856e67000
    [  +0.000002] R13: 0000000000000000 R14: ffff9e8856e67000 R15: 000000004559fca8
    [  +0.000002] FS:  00007fadaa6fc940(0000) GS:ffff9e8b4ebc0000(0000) knlGS:0000000000000000
    [  +0.000003] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    [  +0.000002] CR2: 000056150d213334 CR3: 0000000117950000 CR4: 00000000003506e0
    [  +0.000003] Call Trace:
    [  +0.000002]  drm_new_set_master+0x7a/0x100 [drm]
    [  +0.000040]  drm_master_open+0x68/0x90 [drm]
    [  +0.000038]  drm_open+0xf5/0x240 [drm]
    [  +0.000039]  drm_stub_open+0xab/0x130 [drm]
    [  +0.000041]  chrdev_open+0xca/0x240
    [  +0.000004]  ? cdev_device_add+0x90/0x90
    [  +0.000004]  do_dentry_open+0x14e/0x380
    [  +0.000003]  path_openat+0xb92/0x1050
    [  +0.000006]  ? inotify_handle_inode_event+0x1c0/0x1f0
    [  +0.000006]  do_filp_open+0x9c/0x140
    [  +0.000005]  do_sys_openat2+0xb1/0x160
    [  +0.000005]  __x64_sys_openat+0x54/0x90
    [  +0.000003]  do_syscall_64+0x33/0x40
    [  +0.000005]  entry_SYSCALL_64_after_hwframe+0x44/0xae
    [  +0.000004] RIP: 0033:0x7fadab0fae24
    [  +0.000003] Code: 24 20 eb 8f 66 90 44 89 54 24 0c e8 c6 53 f9 ff 44 8b 54 24 0c 44 89 e2 48 89 ee 41 89 c0 bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 77 34 44 89 c7 89 44 24 0c e8 18 54 f9 ff 8b 44
    [  +0.000003] RSP: 002b:00007fff3c0c3800 EFLAGS: 00000293 ORIG_RAX: 0000000000000101
    [  +0.000003] RAX: ffffffffffffffda RBX: 000056150d6b1de0 RCX: 00007fadab0fae24
    [  +0.000002] RDX: 0000000000080002 RSI: 000056150d630920 RDI: 00000000ffffff9c
    [  +0.000002] RBP: 000056150d630920 R08: 0000000000000000 R09: 000056150cf3f010
    [  +0.000002] R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000080002
    [  +0.000002] R13: 000056150d630920 R14: 000056150d630920 R15: 0000000000000002
    [  +0.000004] ---[ end trace ba55af76f69314c4 ]---
    [  +0.000087] ------------[ cut here ]------------
    [  +0.000002] WARNING: CPU: 7 PID: 549 at /build/nvidia/src/nvidia/465.27/build/nvidia-drm/nvidia-drm-drv.c:568 nv_drm_master_set+0x22/0x30 [nvidia_drm]
    [  +0.000010] Modules linked in: nvidia_drm(POE) nvidia_modeset(POE) nvidia(POE) cfg80211 snd_usb_audio snd_usbmidi_lib intel_rapl_msr rfkill snd_rawmidi snd_seq_device intel_rapl_common joydev mousedev mc 8021q snd_hda_codec_realtek garp edac_mce_amd mrp snd_hda_codec_generic stp snd_hda_codec_hdmi llc ledtrig_audio kvm_amd ccp snd_hda_intel rng_core snd_intel_dspcfg snd_intel_sdw_acpi snd_hda_codec kvm snd_hda_core nls_iso8859_1 snd_hwdep vfat irqbypass fat snd_pcm usbhid crct10dif_pclmul crc32_pclmul wmi_bmof mxm_wmi drm_kms_helper ghash_clmulni_intel snd_timer igb aesni_intel cec snd crypto_simd syscopyarea cryptd sysfillrect sp5100_tco i2c_algo_bit sysimgblt rapl k10temp pcspkr i2c_piix4 fb_sys_fops soundcore dca wmi gpio_amdpt pinctrl_amd gpio_generic mac_hid acpi_cpufreq drm sg fuse agpgart bpf_preload ip_tables x_tables ext4 crc32c_generic crc16 mbcache jbd2 xhci_pci crc32c_intel xhci_pci_renesas
    [  +0.000070] CPU: 7 PID: 549 Comm: Xorg Tainted: P        W  OE     5.12.3-arch1-1 #1
    [  +0.000003] Hardware name: Micro-Star International Co., Ltd. MS-7B78/X470 GAMING PRO CARBON (MS-7B78), BIOS 2.80 03/06/2019
    [  +0.000002] RIP: 0010:nv_drm_master_set+0x22/0x30 [nvidia_drm]
    [  +0.000006] Code: e4 ef 4f c8 0f 1f 40 00 0f 1f 44 00 00 48 8b 47 38 48 8b 78 20 48 8b 05 9c 5c 00 00 48 8b 40 28 e8 93 9c 87 c8 84 c0 74 01 c3 <0f> 0b c3 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 80 3d 7c
    [  +0.000004] RSP: 0018:ffffc11c01a87bc8 EFLAGS: 00010246
    [  +0.000002] RAX: 0000000000000000 RBX: ffff9e886bdcec00 RCX: 0000000000000008
    [  +0.000002] RDX: ffffffffc0f5ee58 RSI: 0000000000000286 RDI: ffffffffc0f5ee20
    [  +0.000002] RBP: ffff9e8850ba72c0 R08: 0000000000000008 R09: ffffc11c01a87bb0
    [  +0.000002] R10: 0000000000000000 R11: 0000000000000000 R12: ffff9e8856e67000
    [  +0.000002] R13: 0000000000000000 R14: ffff9e8856e67000 R15: 000000004559fca8
    [  +0.000002] FS:  00007fadaa6fc940(0000) GS:ffff9e8b4ebc0000(0000) knlGS:0000000000000000
    [  +0.000002] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    [  +0.000002] CR2: 000056150d213334 CR3: 0000000117950000 CR4: 00000000003506e0
    [  +0.000003] Call Trace:
    [  +0.000002]  drm_new_set_master+0x7a/0x100 [drm]
    [  +0.000039]  drm_master_open+0x68/0x90 [drm]
    [  +0.000038]  drm_open+0xf5/0x240 [drm]
    [  +0.000039]  drm_stub_open+0xab/0x130 [drm]
    [  +0.000041]  chrdev_open+0xca/0x240
    [  +0.000004]  ? cdev_device_add+0x90/0x90
    [  +0.000004]  do_dentry_open+0x14e/0x380
    [  +0.000004]  path_openat+0xb92/0x1050
    [  +0.000005]  ? inotify_handle_inode_event+0x1c0/0x1f0
    [  +0.000006]  do_filp_open+0x9c/0x140
    [  +0.000006]  do_sys_openat2+0xb1/0x160
    [  +0.000004]  __x64_sys_openat+0x54/0x90
    [  +0.000003]  do_syscall_64+0x33/0x40
    [  +0.000005]  entry_SYSCALL_64_after_hwframe+0x44/0xae
    [  +0.000004] RIP: 0033:0x7fadab0fae24
    [  +0.000002] Code: 24 20 eb 8f 66 90 44 89 54 24 0c e8 c6 53 f9 ff 44 8b 54 24 0c 44 89 e2 48 89 ee 41 89 c0 bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 77 34 44 89 c7 89 44 24 0c e8 18 54 f9 ff 8b 44
    [  +0.000004] RSP: 002b:00007fff3c0c3660 EFLAGS: 00000293 ORIG_RAX: 0000000000000101
    [  +0.000003] RAX: ffffffffffffffda RBX: 000056150d7374c0 RCX: 00007fadab0fae24
    [  +0.000002] RDX: 0000000000080002 RSI: 000056150d630920 RDI: 00000000ffffff9c
    [  +0.000001] RBP: 000056150d630920 R08: 0000000000000000 R09: 000056150cf3f010
    [  +0.000002] R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000080002
    [  +0.000002] R13: 000056150d630920 R14: 0000000000000000 R15: 000056150d6b0930
    [  +0.000004] ---[ end trace ba55af76f69314c5 ]---
    [May17 04:21] [drm:nv_drm_connector_get_modes [nvidia_drm]] *ERROR* [nvidia-drm] [GPU ID 0x00001c00] Failed to get mode at modeIndex 32 of NvKmsKapiDisplay 0x00000400

This looks suspiciously like a crash-loop until the driver just gives up and falls back to MESA.

The unfortunate result of this is that nothing gpu accelerated is usable, simple video decode maxes out cpu cores, anything more intensive (such as blender) runs at single digit framerates, if even.

I have to upload the bug report here, got a socket-refused complaint when I tried to attach it to the main post, apologies.
nvidia-bug-report.log.gz (271.9 KB)

nvidia-drm.modeset=1 and forcing early loading of nvidia via mkinitcpio: MODULES=(nvidia nvidia_modeset nvidia_uvm nvidia_drm) solves it.

that more or less proves it’s a race condition, very peculiar that it broke randomly since it’s worked for years, but oh well.