Kernel Oops on boot, 5.9.13 with 455.45.01

GPU Unix Graphics Linux
#1

Hi

It seems that I’ve been getting an oops on boot for a while, but haven’t noticed. There’s no noticeable problem I can see.

Here’s the oops:

[   20.673580] RIP: 0010:nv_drm_master_set+0x22/0x30 [nvidia_drm]
[   20.673582] Code: c3 0f 1f 80 00 00 00 00 0f 1f 44 00 00 48 8b 47 48 48 8b 78 20 48 8b 05 0c 5d 00 00 48 8b 40 28 e8 e3 07 77 f6 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 8c
[   20.673583] RSP: 0018:ffffa45104f53c00 EFLAGS: 00010246
[   20.673584] RAX: 0000000000000000 RBX: ffff8f182737ba00 RCX: 0000000000000008
[   20.673585] RDX: ffffffffc264eed8 RSI: 0000000000000292 RDI: 0000000000000292
[   20.673586] RBP: ffff8f1875f2ecc0 R08: 0000000000000008 R09: ffffa45104f53be8
[   20.673586] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8f188ab63000
[   20.673587] R13: 0000000000000000 R14: ffff8f188ab63000 R15: 000000009c416ba8
[   20.673588] FS:  00007f72082dcb80(0000) GS:ffff8f189ed00000(0000) knlGS:0000000000000000
[   20.673589] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   20.673590] CR2: 000055bdfd713e08 CR3: 000000038f0b2006 CR4: 00000000001706e0
[   20.673591] Call Trace:
[   20.673609]  drm_new_set_master+0x7a/0x100 [drm]
[   20.673622]  drm_master_open+0x68/0x90 [drm]
[   20.673632]  drm_open+0xf8/0x250 [drm]
[   20.673645]  drm_stub_open+0xab/0x130 [drm]
[   20.673649]  chrdev_open+0xdd/0x210
[   20.673651]  ? cdev_device_add+0x90/0x90
[   20.673653]  do_dentry_open+0x14b/0x360
[   20.673656]  path_openat+0xa70/0xfb0
[   20.673659]  ? vsnprintf+0x387/0x4e0
[   20.673661]  ? page_counter_uncharge+0x36/0x50
[   20.673663]  do_filp_open+0x75/0x100
[   20.673665]  ? __check_object_size+0x136/0x150
[   20.673667]  ? __alloc_fd+0x44/0x150
[   20.673669]  do_sys_openat2+0x7b/0x130
[   20.673671]  __x64_sys_openat+0x46/0x70
[   20.673673]  do_syscall_64+0x33/0x40
[   20.673676]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

And here’s the bug report:
nvidia-bug-report.log.gz (1.2 MB)

Regards
elFarto

#2

Same issue with 5.9.15 and 460.27.04.

#3

I’m observing the same kernel oops on Fedora 33 with 5.9.16 and 460.27.04. It’s been happening for a while, but only when I enable options nvidia-drm modeset=1. If I don’t enable this option then my monitor has trouble syncing (display remains blank) after rebooting. Since the kernel oops doesn’t appear to cause any issues as @elFarto mentioned I’ve chosen to leave the module option enabled to resolve the previously mentioned display issue. In my scenario modesetting doesn’t appear to be required for a nice graphical boot on first boot due to UEFI support for setting the resolution at boot and GRUB leaving the resolution alone.

#4

The Xorg modesetting DDX seems to be fighting with the Nvidia DDX for DRM nodes

[   463.657] (II) modeset(G0): using drv /dev/dri/card0

but

[   463.658] (II) Applying OutputClass "nvidia" options to /dev/dri/card0

Nvidia appears to be adding a lot of DRM related stuff to the kernel driver (so it looks a lot like a real DRM driver to userspace now) and the modesetting DDX is getting further into its initialization.

In my case, pointing the modesetting DDX to only look at non-Nvidia devices (the kmsdev option) and ensuring all the Nvidia kernel modules are fully loaded (instead of having them load on-demand) before starting X worked around this. The latter is for some weird race condition where the Nvidia driver is only partially loaded and https://gitlab.freedesktop.org/xorg/xserver/-/blob/master/config/udev.c#L135 fails, which causes modesetting to load regardless (it’s hardcoded in xf86platformAddDevice)

The WARN_ON itself can still be triggered by simply opening a Nvidia primary DRM node though, e.g. with https://gitlab.freedesktop.org/mesa/drm/-/blob/master/tests/drmdevice.c, when some other DRM client like X or fbcon already has master. Because of https://patchwork.freedesktop.org/patch/367748 the Nvidia kernel driver can no longer use its internal grabOwnership to report if DRM master can be taken.

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