Re: [REGRESSION] drm/nouveau: NULL pointer dereference in drm_atomic_commit during GP107 initialization

[Thorsten Leemhuis]

On 11/2/26 13:47, Eric Kim wrote:
> 
> On my laptop, which has GP107 GPU with intel graphics and uses nouveau
> driver, booting kernels after commit
> 2652aca460dcfdd0d169bbfa358aa15804dc736b causes NULL pointer dereference
> at initialization.

Thx for your report. Hmm, no reply yet afaics. Wondering if it would
have been better to report it at the dedicated place for nouveau kernel
bugs: https://gitlab.freedesktop.org/drm/nouveau/-/work_items/

You thus might want to at least check if any similar reports are found
there.

Would also be good to know if reverting 2652aca460dc ontop of latest
mainline fixes this.

Ciao, Thorsten
> [   17.556328] [drm] Initialized nouveau 1.4.3 for 0000:01:00.0 on minor 0
> [   17.556364] nouveau 0000:01:00.0: [drm] No compatible format found
> [   17.556792] nouveau 0000:01:00.0: [drm] Cannot find any crtc or sizes
> [   17.557237] BUG: kernel NULL pointer dereference, address:
> 0000000000000000
> [   17.583880] #PF: supervisor instruction fetch in kernel mode
> [   17.598078] #PF: error_code(0x0010) - not-present page
> [   17.601475] PGD 0 P4D 0 [   17.608839] Oops: Oops: 0010 [#1] SMP PTI
> [   17.608914] CPU: 6 UID: 0 PID: 1443 Comm: modprobe Not tainted 7.3.0+
> #1 PREEMPT(lazy) [   17.608954] Hardware name: SAMSUNG ELECTRONICS CO.,
> LTD. 800G5M/800G5W/NT800G5M-X78W, BIOS P11RDV.075.170829.XJ 08/29/2017
> [   17.608990] RIP: 0010:0x0
> [   17.609090] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
> [   17.610081] RSP: 0018:ffffca4d86537828 EFLAGS: 00010246
> [   17.610135] RAX: 0000000000000000 RBX: ffff89b74dcf1180 RCX:
> ffffffffa97d8091
> [   17.610172] RDX: 0000000000000000 RSI: ffff89b74dcf1180 RDI:
> ffff89b74c466800
> [   17.610207] RBP: ffff89b74c466800 R08: ffff89b74dcf1180 R09:
> 0000000000000000
> [   17.610245] R10: 0000000000000010 R11: ffffffffa9b65410 R12:
> ffff89b74c466800
> [   17.610283] R13: 0000000000000001 R14: ffff89b74c466800 R15:
> ffff89b77f1a2400
> [   17.610320] FS:  00007fc4a888d780(0000) GS:ffff89bac4364000(0000)
> knlGS:0000000000000000
> [   17.610357] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   17.610414] CR2: ffffffffffffffd6 CR3: 0000000144b20004 CR4:
> 00000000003726f0
> [   17.610448] Call Trace:
> [   17.610483]  <TASK>
> [   17.610521]  drm_atomic_commit+0xb1/0xe0
> [   17.610558]  ? __pfx___drm_printfn_info+0x10/0x10
> [   17.610590]  drm_client_modeset_commit_atomic+0x25c/0x2d0
> [   17.610618]  drm_client_modeset_commit_locked+0x5a/0x170
> [   17.610647]  ? drm_master_internal_acquire+0x1d/0x40
> [   17.610675]  drm_client_modeset_commit+0x25/0x40
> [   17.610700]  drm_fb_helper_single_fb_probe+0x1aa/0x1c0
> [   17.610729]  __drm_fb_helper_initial_config_and_unlock+0xa8/0x1b0
> [   17.610754]  drm_fbdev_client_hotplug+0x79/0xb0
> [   17.610782]  ? drm_client_init+0x13e/0x180
> [   17.610811]  drm_client_register+0x79/0xc0
> [   17.610839]  drm_fbdev_client_setup+0xc9/0x1c0
> [   17.610867]  drm_client_setup+0x6a/0x90
> [   17.610893]  nouveau_drm_probe+0x15b/0x1e0 [nouveau]
> [   17.610922]  local_pci_probe+0x4a/0x90
> [   17.610951]  ? cpu_hotplug_disable+0x15/0x30
> [   17.610977]  pci_call_probe+0x5a/0x1a0
> [   17.611009]  pci_device_probe+0xdb/0x180
> [   17.611060]  call_driver_probe+0x23/0x100
> [   17.611104]  ? driver_sysfs_add+0x55/0xc0
> [   17.611137]  really_probe+0xd7/0x2d0
> [   17.611171]  ? __pm_runtime_resume+0x50/0x60
> [   17.611220]  __driver_probe_device+0x9c/0x1b0
> [   17.611261]  driver_probe_device+0x1f/0x80
> [   17.611297]  ? __pfx___driver_attach+0x10/0x10
> [   17.611335]  __driver_attach+0xcc/0x200
> [   17.611373]  ? __pfx___driver_attach+0x10/0x10
> [   17.611409]  bus_for_each_dev+0x97/0x100
> [   17.611451]  bus_add_driver+0x1d0/0x280
> [   17.611493]  ? __pfx_init_module+0x10/0x10 [nouveau]
> [   17.611530]  ? __pfx_init_module+0x10/0x10 [nouveau]
> [   17.611567]  driver_register+0x75/0xe0
> [   17.611602]  nouveau_drm_init+0x60/0xff0 [nouveau]
> [   17.611633]  do_one_initcall+0x89/0x3d0
> [   17.611667]  do_init_module+0x8e/0x290
> [   17.611703]  init_module_from_file+0xc8/0x180
> [   17.611736]  idempotent_init_module+0x23e/0x360
> [   17.611773]  __x64_sys_finit_module+0x7f/0x110
> [   17.611805]  do_syscall_64+0xbe/0x470
> [   17.611844]  ? do_syscall_64+0x37/0x470
> [   17.611883]  entry_SYSCALL_64_after_hwframe+0x76/0x7e
> 
> It boots without this problem when booting with nouveau.atomic=0
> kernel parameter.
> 
> My guess is that atomic_(commit|check) operation is not present in
> nouveau_mode_config_funcs, and commit
> 2652aca460dcfdd0d169bbfa358aa15804dc736b enabled
> atomic modesetting by default for NV50+ gpus caused
> the problem.
> 
> Also, drm_helper_(commit|check) was added to nouveau_mode_config_funcs
> at commit 604826acb3f53c6648a7ee99a3914ead680ab7fb, but it was
> reverted at commit 6c65db809796717f0a96cf22f80405dbc1a31a4b due to
> unreliability.
> 
> I hope this problem can be fixed at one of the next releases.
> 
> Thanks,
> Eric Kim
> 
> #regzbot introduced: 2652aca460dc