nouveau 0000:01:00.0: drm_WARN_ON(!found_head)

nouveau 0000:01:00.0: drm_WARN_ON(!found_head)

[Borislav Petkov]

Hi,

this is ontop of Linus' tree from the 4th (lemme know if I should try
the latest) on one of my test boxes:

nouveau 0000:01:00.0: vgaarb: deactivate vga console
Console: switching to colour dummy device 80x25
nouveau 0000:01:00.0: NVIDIA GT218 (0a8280b1)
CE: hpet increased min_delta_ns to 20115 nsec
nouveau 0000:01:00.0: bios: version 70.18.49.00.00
nouveau 0000:01:00.0: fb: 1024 MiB DDR3
nouveau 0000:01:00.0: DRM: VRAM: 1024 MiB
nouveau 0000:01:00.0: DRM: GART: 1048576 MiB
nouveau 0000:01:00.0: DRM: TMDS table version 2.0
nouveau 0000:01:00.0: DRM: MM: using COPY for buffer copies
------------[ cut here ]------------
nouveau 0000:01:00.0: drm_WARN_ON(!found_head)
WARNING: CPU: 4 PID: 786 at drivers/gpu/drm/nouveau/dispnv50/disp.c:2731 nv50_display_init+0x28c/0x4f0 [nouveau]
Modules linked in: nouveau(+) drm_ttm_helper ttm video drm_exec drm_gpuvm gpu_sched drm_display_helper wmi
CPU: 4 PID: 786 Comm: systemd-udevd Not tainted 6.6.0+ #1
Hardware name: MICRO-STAR INTERNATIONAL CO.,LTD MS-7599/870-C45 (MS-7599), BIOS V1.15 03/04/2011
RIP: 0010:nv50_display_init+0x28c/0x4f0 [nouveau]
Code: 4c 8b 6f 50 4d 85 ed 75 03 4c 8b 2f e8 6d 47 37 e1 48 c7 c1 4c 55 2d a0 48 89 c6 4c 89 ea 48 c7 c7 42 55 2d a0 e8 44 83 e8 e0 <0f> 0b 48 8b 43 08 49 39 c6 48 8d 58 f8 0f 85 41 ff ff ff 48 8d 7c
RSP: 0018:ffffc9000031ba98 EFLAGS: 00010286
RAX: 000000000000002e RBX: ffff888100a21400 RCX: 0000000000000000
RDX: 0000000000000002 RSI: ffffc9000031b9b0 RDI: 0000000000000001
RBP: ffff888104eadad0 R08: ffff888136ffdfe8 R09: 0000000000000058
R10: 0000000000000289 R11: ffff888136401cd8 R12: ffff888104ead800
R13: ffff888100abddf0 R14: ffff888104eadab0 R15: 0000000000000000
FS:  00007fef9c8e38c0(0000) GS:ffff88812f500000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fef9ce9d258 CR3: 000000010330e000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 ? __warn+0x97/0x160
 ? nv50_display_init+0x28c/0x4f0 [nouveau]
 ? report_bug+0x1ec/0x200
 ? handle_bug+0x3c/0x70
 ? exc_invalid_op+0x1f/0x90
 ? asm_exc_invalid_op+0x16/0x20
 ? nv50_display_init+0x28c/0x4f0 [nouveau]
 ? nv50_display_init+0x28c/0x4f0 [nouveau]
 ? sched_set_fifo+0x46/0x60
 nouveau_display_init+0xa0/0xd0 [nouveau]
 nouveau_drm_device_init+0x42a/0x990 [nouveau]
 nouveau_drm_probe+0x105/0x240 [nouveau]
 ? __pm_runtime_resume+0x68/0xa0
 pci_device_probe+0xaa/0x140
 really_probe+0xc2/0x2d0
 __driver_probe_device+0x73/0x120
 driver_probe_device+0x2c/0xb0
 __driver_attach+0xa0/0x150
 ? __device_attach_driver+0xc0/0xc0
 bus_for_each_dev+0x67/0xa0
 bus_add_driver+0x10e/0x210
 driver_register+0x5c/0x120
 ? 0xffffffffa0336000
 do_one_initcall+0x44/0x200
 ? kmalloc_trace+0x37/0xc0
 do_init_module+0x64/0x230
 init_module_from_file+0x8d/0xd0
 idempotent_init_module+0x15a/0x210
 __x64_sys_finit_module+0x67/0xb0
 do_syscall_64+0x41/0xf0
 entry_SYSCALL_64_after_hwframe+0x4b/0x53
RIP: 0033:0x7fef9cda5ee9
Code: 08 44 89 e0 5b 41 5c c3 66 0f 1f 84 00 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d f7 ee 0e 00 f7 d8 64 89 01 48
RSP: 002b:00007ffeb60299e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
RAX: ffffffffffffffda RBX: 000055b322ddf5a0 RCX: 00007fef9cda5ee9
RDX: 0000000000000000 RSI: 00007fef9cf45e2d RDI: 0000000000000012
RBP: 0000000000020000 R08: 0000000000000000 R09: 000055b322ddf690
R10: 0000000000000012 R11: 0000000000000246 R12: 00007fef9cf45e2d
R13: 0000000000000000 R14: 000055b322dcb940 R15: 000055b322ddf5a0
 </TASK>
---[ end trace 0000000000000000 ]---
[drm] Initialized nouveau 1.4.0 20120801 for 0000:01:00.0 on minor 0
fbcon: nouveaudrmfb (fb0) is primary device
Console: switching to colour frame buffer device 210x65
nouveau 0000:01:00.0: [drm] fb0: nouveaudrmfb frame buffer device

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

Re: nouveau 0000:01:00.0: drm_WARN_ON(!found_head)

[Borislav Petkov]

On Sat, Nov 11, 2023 at 01:03:23PM +0100, Borislav Petkov wrote:
> Hi,
> 
> this is ontop of Linus' tree from the 4th (lemme know if I should try
> the latest) on one of my test boxes:
> 
> nouveau 0000:01:00.0: vgaarb: deactivate vga console
> Console: switching to colour dummy device 80x25
> nouveau 0000:01:00.0: NVIDIA GT218 (0a8280b1)
> CE: hpet increased min_delta_ns to 20115 nsec
> nouveau 0000:01:00.0: bios: version 70.18.49.00.00
> nouveau 0000:01:00.0: fb: 1024 MiB DDR3
> nouveau 0000:01:00.0: DRM: VRAM: 1024 MiB
> nouveau 0000:01:00.0: DRM: GART: 1048576 MiB
> nouveau 0000:01:00.0: DRM: TMDS table version 2.0
> nouveau 0000:01:00.0: DRM: MM: using COPY for buffer copies
> ------------[ cut here ]------------
> nouveau 0000:01:00.0: drm_WARN_ON(!found_head)
> WARNING: CPU: 4 PID: 786 at drivers/gpu/drm/nouveau/dispnv50/disp.c:2731 nv50_display_init+0x28c/0x4f0 [nouveau]
> Modules linked in: nouveau(+) drm_ttm_helper ttm video drm_exec drm_gpuvm gpu_sched drm_display_helper wmi
> CPU: 4 PID: 786 Comm: systemd-udevd Not tainted 6.6.0+ #1

This still fires on -rc5:

[    4.577348] nouveau 0000:01:00.0: vgaarb: deactivate vga console
[    4.584482] Console: switching to colour dummy device 80x25
[    4.590120] nouveau 0000:01:00.0: NVIDIA GT218 (0a8280b1)
[    4.718171] nouveau 0000:01:00.0: bios: version 70.18.49.00.00
[    4.724788] nouveau 0000:01:00.0: fb: 1024 MiB DDR3
[    6.047984] nouveau 0000:01:00.0: DRM: VRAM: 1024 MiB
[    6.053031] nouveau 0000:01:00.0: DRM: GART: 1048576 MiB
[    6.058340] nouveau 0000:01:00.0: DRM: TMDS table version 2.0
[    6.065892] nouveau 0000:01:00.0: DRM: MM: using COPY for buffer copies
[    6.078375] ------------[ cut here ]------------
[    6.082994] nouveau 0000:01:00.0: drm_WARN_ON(!found_head)
[    6.083023] WARNING: CPU: 3 PID: 779 at drivers/gpu/drm/nouveau/dispnv50/disp.c:2731 nv50_display_init+0x28c/0x4f0 [nouve
au]
[    6.099800] Modules linked in: nouveau(+) drm_ttm_helper ttm video drm_exec drm_gpuvm gpu_sched drm_display_helper wmi
[    6.110490] CPU: 3 PID: 779 Comm: systemd-udevd Not tainted 6.7.0-rc5+ #2
[    6.117272] Hardware name: MICRO-STAR INTERNATIONAL CO.,LTD MS-7599/870-C45 (MS-7599), BIOS V1.15 03/04/2011
[    6.127087] RIP: 0010:nv50_display_init+0x28c/0x4f0 [nouveau]
[    6.132915] Code: 4c 8b 6f 50 4d 85 ed 75 03 4c 8b 2f e8 cd 16 37 e1 48 c7 c1 4c 55 2d a0 48 89 c6 4c 89 ea 48 c7 c7 42 5
5 2d a0 e8 44 5a e8 e0 <0f> 0b 48 8b 43 08 49 39 c6 48 8d 58 f8 0f 85 41 ff ff ff 48 8d 7c
[    6.151660] RSP: 0018:ffffc9000036ba98 EFLAGS: 00010286
[    6.156885] RAX: 000000000000002e RBX: ffff8881009fbc00 RCX: 0000000000000000
[    6.164013] RDX: 0000000000000002 RSI: ffffc9000036b9b0 RDI: 0000000000000001
[    6.171141] RBP: ffff888103fc8ad0 R08: ffff888136ffdfe8 R09: 0000000000000058
[    6.178263] R10: 000000000000027a R11: ffff888136401b70 R12: ffff888103fc8800
[    6.185393] R13: ffff888100abddf0 R14: ffff888103fc8ab0 R15: 0000000000000000
[    6.192521] FS:  00007fdc144858c0(0000) GS:ffff88812f4c0000(0000) knlGS:0000000000000000
[    6.200601] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    6.206339] CR2: 000055676cc01000 CR3: 0000000103f6c000 CR4: 00000000000006f0
[    6.213466] Call Trace:
[    6.215921]  <TASK>
[    6.218015]  ? __warn+0x96/0x160
[    6.221240]  ? nv50_display_init+0x28c/0x4f0 [nouveau]
[    6.226461]  ? report_bug+0x1ec/0x200
[    6.230119]  ? handle_bug+0x3c/0x70
[    6.233611]  ? exc_invalid_op+0x1f/0x90
[    6.237442]  ? asm_exc_invalid_op+0x16/0x20
[    6.241622]  ? nv50_display_init+0x28c/0x4f0 [nouveau]
[    6.246840]  ? nv50_display_init+0x28c/0x4f0 [nouveau]
[    6.252058]  ? sched_set_fifo+0x46/0x60
[    6.255897]  nouveau_display_init+0xa0/0xd0 [nouveau]
[    6.261031]  nouveau_drm_device_init+0x42a/0x990 [nouveau]
[    6.266604]  nouveau_drm_probe+0x105/0x240 [nouveau]
[    6.271651]  ? __pm_runtime_resume+0x68/0xa0
[    6.275920]  pci_device_probe+0xaa/0x140
[    6.279840]  really_probe+0xc2/0x2d0
[    6.283411]  __driver_probe_device+0x73/0x120
[    6.287761]  driver_probe_device+0x2c/0xb0
[    6.291851]  __driver_attach+0xa0/0x150
[    6.295683]  ? __device_attach_driver+0xc0/0xc0
[    6.300205]  bus_for_each_dev+0x67/0xa0
[    6.304044]  bus_add_driver+0x10e/0x210
[    6.307874]  driver_register+0x5c/0x120
[    6.311706]  ? 0xffffffffa0336000
[    6.315017]  do_one_initcall+0x44/0x200
[    6.318851]  ? kmalloc_trace+0x37/0xc0
[    6.322595]  do_init_module+0x64/0x230
[    6.326344]  init_module_from_file+0x8d/0xd0
[    6.330609]  idempotent_init_module+0x15a/0x210
[    6.335136]  __x64_sys_finit_module+0x67/0xb0
[    6.339490]  do_syscall_64+0x41/0xf0
[    6.343066]  entry_SYSCALL_64_after_hwframe+0x4b/0x53
[    6.348118] RIP: 0033:0x7fdc14947ee9
[    6.351691] Code: 08 44 89 e0 5b 41 5c c3 66 0f 1f 84 00 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d f7 ee 0e 00 f7 d8 64 89 01 48
[    6.370433] RSP: 002b:00007ffe228d74b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
[    6.377993] RAX: ffffffffffffffda RBX: 000055676cc11d60 RCX: 00007fdc14947ee9
[    6.385116] RDX: 0000000000000000 RSI: 00007fdc14ae7e2d RDI: 0000000000000012
[    6.392245] RBP: 0000000000020000 R08: 0000000000000000 R09: 000055676cc0f170
[    6.399368] R10: 0000000000000012 R11: 0000000000000246 R12: 00007fdc14ae7e2d
[    6.406496] R13: 0000000000000000 R14: 000055676cc0c230 R15: 000055676cc11d60
[    6.413621]  </TASK>
[    6.415803] ---[ end trace 0000000000000000 ]---
[    6.420697] [drm] Initialized nouveau 1.4.0 20120801 for 0000:01:00.0 on minor 0
[    6.469632] fbcon: nouveaudrmfb (fb0) is primary device
[    6.548495] Console: switching to colour frame buffer device 210x65
[    6.563870] nouveau 0000:01:00.0: [drm] fb0: nouveaudrmfb frame buffer device
[    6.660166] EXT4-fs (sda5): mounted filesystem 6fe02972-f7b5-4f2d-9796-e78fe2d6b511 ro with ordered data mode. Quota mode: disabled.
[    7.226100] acpi_cpufreq: overriding BIOS provided _PSD data
[    7.609728] kvm_amd: Nested Virtualization enabled
[    7.614585] kvm_amd: Nested Paging enabled
[    7.618825] kvm_amd: LBR virtualization supported
[    7.656480] MCE: In-kernel MCE decoding enabled.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

Re: nouveau 0000:01:00.0: drm_WARN_ON(!found_head)

[Borislav Petkov]

On Tue, Dec 12, 2023 at 10:35:51PM -0500, Paul Dufresne wrote:
> https://gitlab.freedesktop.org/drm/nouveau/-/issues/282

Let's add more folks who were involved in

1b477f42285e ("drm/nouveau/kms: Add INHERIT ioctl to nvkm/nvif for reading IOR state")

Apparently, someone wants to know that the loop over the crtcs in
nv50_display_read_hw_or_state() didn't find a head.

Holler if you need me to run a debug patch to figure out why.

We're getting close to releasing so I guess we either debug this or shut
up the WARN.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

Re: nouveau 0000:01:00.0: drm_WARN_ON(!found_head)

[Borislav Petkov]

On Wed, Dec 13, 2023 at 12:39:36PM +0100, Borislav Petkov wrote:
> We're getting close to releasing so I guess we either debug this or shut
> up the WARN.

Not only that - panic_on_warn turns this into an explosion so you don't
want that in a released kernel.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

Re: nouveau 0000:01:00.0: drm_WARN_ON(!found_head)

[Lyude Paul]

agh - thank you for repeatedly poking on this, I've been busy enough with GSP
work I totally missed this. Yes - I'm quite surprised that this is blowing up,
but considering that looks to be a GT218 I guess display state readback must
just work a bit differently there since that's really early on into the NV50
days.

The reason that was a drm_WARN_ON() was because it indicates that we're not
reading back OR -> head assignments properly. But, I'm confused how we're even
getting that far on a non-GSP platform. I'm going to dig into this now, but if
I don't figure out a good fix by the end of the day I'll just send a patch to
silent the warning.

Thanks again for bugging me about this!

On Wed, 2023-12-13 at 13:49 +0100, Borislav Petkov wrote:
> On Wed, Dec 13, 2023 at 12:39:36PM +0100, Borislav Petkov wrote:
> > We're getting close to releasing so I guess we either debug this or shut
> > up the WARN.
> 
> Not only that - panic_on_warn turns this into an explosion so you don't
> want that in a released kernel.
> 

-- 
Cheers,
 Lyude Paul (she/her)
 Software Engineer at Red Hat

Re: nouveau 0000:01:00.0: drm_WARN_ON(!found_head)

[Lyude Paul]

Hopefully you're still on at this point - if you are, could you try starting
the machine up with the following kernel module arguments passed to nouveau?

debug=disp=trace

Then see if you can find any lines that mention INHERIT? I have a feeling I'm
just going to have to add a workaround for the time being, but I'd really love
to know how we're managing to get that far on a hardware generation we never
implemented that nvkm ioctl for…

On Wed, 2023-12-13 at 18:37 -0500, Lyude Paul wrote:
> agh - thank you for repeatedly poking on this, I've been busy enough with GSP
> work I totally missed this. Yes - I'm quite surprised that this is blowing up,
> but considering that looks to be a GT218 I guess display state readback must
> just work a bit differently there since that's really early on into the NV50
> days.
> 
> The reason that was a drm_WARN_ON() was because it indicates that we're not
> reading back OR -> head assignments properly. But, I'm confused how we're even
> getting that far on a non-GSP platform. I'm going to dig into this now, but if
> I don't figure out a good fix by the end of the day I'll just send a patch to
> silent the warning.
> 
> Thanks again for bugging me about this!
> 
> On Wed, 2023-12-13 at 13:49 +0100, Borislav Petkov wrote:
> > On Wed, Dec 13, 2023 at 12:39:36PM +0100, Borislav Petkov wrote:
> > > We're getting close to releasing so I guess we either debug this or shut
> > > up the WARN.
> > 
> > Not only that - panic_on_warn turns this into an explosion so you don't
> > want that in a released kernel.
> > 
> 

-- 
Cheers,
 Lyude Paul (she/her)
 Software Engineer at Red Hat

Re: nouveau 0000:01:00.0: drm_WARN_ON(!found_head)

[Lyude Paul]

Nevermind - I don't think I'll need the logs, I stared at the code for long
enough and I think I realized what's happening.

I will have a patch for you to test in just a moment, just waiting for it to
compile so I can verify nothing else breaks

On Wed, 2023-12-13 at 18:48 -0500, Lyude Paul wrote:
> Hopefully you're still on at this point - if you are, could you try starting
> the machine up with the following kernel module arguments passed to nouveau?
> 
> debug=disp=trace
> 
> Then see if you can find any lines that mention INHERIT? I have a feeling I'm
> just going to have to add a workaround for the time being, but I'd really love
> to know how we're managing to get that far on a hardware generation we never
> implemented that nvkm ioctl for…
> 
> On Wed, 2023-12-13 at 18:37 -0500, Lyude Paul wrote:
> > agh - thank you for repeatedly poking on this, I've been busy enough with GSP
> > work I totally missed this. Yes - I'm quite surprised that this is blowing up,
> > but considering that looks to be a GT218 I guess display state readback must
> > just work a bit differently there since that's really early on into the NV50
> > days.
> > 
> > The reason that was a drm_WARN_ON() was because it indicates that we're not
> > reading back OR -> head assignments properly. But, I'm confused how we're even
> > getting that far on a non-GSP platform. I'm going to dig into this now, but if
> > I don't figure out a good fix by the end of the day I'll just send a patch to
> > silent the warning.
> > 
> > Thanks again for bugging me about this!
> > 
> > On Wed, 2023-12-13 at 13:49 +0100, Borislav Petkov wrote:
> > > On Wed, Dec 13, 2023 at 12:39:36PM +0100, Borislav Petkov wrote:
> > > > We're getting close to releasing so I guess we either debug this or shut
> > > > up the WARN.
> > > 
> > > Not only that - panic_on_warn turns this into an explosion so you don't
> > > want that in a released kernel.
> > > 
> > 
> 

-- 
Cheers,
 Lyude Paul (she/her)
 Software Engineer at Red Hat