Both my PCs had the v4l2loopback error. I upgraded them from Ubuntu 24.04 lts to 26.04 lts about two weeks ago and have not had the error since. Loading v4l2loopback okay now. # System Details Report ---
## Report details - **Date generated:** 2026-09-11 16:28:06 ## Hardware Information: - **Hardware Model:** Dell Inc. Precision 7510 - **Memory:** 32.0 GiB - **Processor:** Intel® Xeon® E3-1505M v5 × 8 - **Graphics:** Intel® HD Graphics P530 (SKL GT2) - **Graphics 1:** Quadro M2000M - **Disk Capacity:** 512.1 GB ## Software Information: - **Firmware Version:** 1.31.3 - **OS Name:** Ubuntu 26.04 LTS - **OS Build:** (null) - **OS Type:** 64-bit - **GNOME Version:** 50 - **Windowing System:** Wayland - **Kernel Version:** Linux 7.0.0-31-generic tom-brown@tom-brown-Precision-7510:~$ lsmod | grep v4l2loopback v4l2loopback_dc 40960 0 videodev 376832 3 videobuf2_v4l2,v4l2loopback_dc,uvcvideo tom-brown@tom-brown-Precision-7510:~$ modinfo v4l2loopback filename: /lib/modules/7.0.0-31-generic/updates/dkms/v4l2loopback.ko.zst alias: char-major-10-255 license: GPL version: 0.15.3 author: Vasily Levin, IOhannes m zmoelnig <[email protected]>,Stefan Diewald,Anton Novikovet al. description: V4L2 loopback video device srcversion: 7B773B9EB594AD896DAD368 depends: videodev name: v4l2loopback retpoline: Y vermagic: 7.0.0-31-generic SMP preempt mod_unload modversions On Fri, Sep 11, 2026 at 2:10 PM Andreas Hasenack <[email protected]> wrote: > Hello John, or anyone else affected, > > Accepted v4l2loopback into noble-proposed. The package will build now > and be available at > https://launchpad.net/ubuntu/+source/v4l2loopback/0.12.7-2ubuntu5.2 in a > few hours, and then in the -proposed repository. > > Please help us by testing this new package. See > https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how > to enable and use -proposed. Your feedback will aid us getting this > update out to other Ubuntu users. > > If this package fixes the bug for you, please add a comment to this bug, > mentioning the version of the package you tested, what testing has been > performed on the package and change the tag from verification-needed- > noble to verification-done-noble. If it does not fix the bug for you, > please add a comment stating that, and change the tag to verification- > failed-noble. In either case, without details of your testing we will > not be able to proceed. > > Further information regarding the verification process can be found at > https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in > advance for helping! > > N.B. The updated package will be released to -updates after the bug(s) > fixed by this package have been verified and the package has been in > -proposed for a minimum of 7 days. > > ** Changed in: v4l2loopback (Ubuntu Noble) > Status: In Progress => Fix Committed > > ** Tags added: verification-needed-noble > > -- > You received this bug notification because you are subscribed to the bug > report. > https://bugs.launchpad.net/bugs/2161037 > > Title: > v4l2loopback fails to build and then oopses on kernel 7.0 HWE > > Status in v4l2loopback package in Ubuntu: > Fix Released > Status in v4l2loopback source package in Noble: > Fix Committed > > Bug description: > [Impact] > > Linux 6.18 added a "struct file *filp" parameter to v4l2_fh_add() and > v4l2_fh_del() (include/media/v4l2-fh.h). > > v4l2loopback 0.12.7 still calls both with the old single-argument > signature, so the DKMS build fails against the noble 7.0 HWE kernel: > v4l2loopback.c:2089: error: too few arguments to function > 'v4l2_fh_add' > v4l2loopback.c:2117: error: too few arguments to function > 'v4l2_fh_del' > > dkms autoinstall runs from /etc/kernel/header_postinst.d/dkms, so the > build failure aborts the kernel header postinst with exit status 11 > and leaves the kernel meta package unconfigured. > > Later apt operations then exit non-zero, including security updates, > and the kernel package stays unconfigured until v4l2loopback-dkms is > removed or a fixed version is installed. > > linux-hwe-7.0 is published in both noble-updates and noble-security, > so affected systems receive the kernel automatically. > > Linux 6.18 also requires the new file_to_v4l2_fh() accessor to reach the > file handle, so with only the signature fix the module builds and loads but > oopses on the first ioctl a consumer issues against the device: > BUG: unable to handle page fault for address: fffffffffffffffc > RIP: 0010:vidioc_reqbufs+0xa2/0x3b0 [v4l2loopback] > > Both fixes are in this upload. > > [Test Plan] > > On a noble system that has v4l2loopback-dkms installed and does not yet > have the 7.0 HWE headers: > sudo apt-get install -y linux-headers-7.0.0-28-generic > > - Without the fix > run-parts: /etc/kernel/header_postinst.d/dkms exited with return > code 11 > dpkg: error processing package linux-headers-7.0.0-28-generic > (--configure) > E: Sub-process /usr/bin/dpkg returned an error code (1) > > sudo dpkg --audit > > dpkg --audit lists both linux-headers-7.0.0-28-generic and > v4l2loopback-dkms as half configured. > > - With the fix > sudo apt-get install -y -t noble-proposed v4l2loopback-dkms > dkms status v4l2loopback > > The header package configures cleanly and dkms status reports > v4l2loopback installed for 7.0.0-28-generic. > "sudo dpkg --audit" now prints nothing, without removing > v4l2loopback-dkms. > The GA kernel must be unaffected on the same system: > > sudo apt-get install -y linux-headers-6.8.0-136-generic > dkms status v4l2loopback > > The module must also build for the GA kernel, and the streaming check > below must pass on it as well. > The oops fix, booted into 7.0 and then repeated on the GA kernel. > video_nr pins the device so a real webcam cannot take the number: > > sudo modprobe v4l2loopback devices=1 video_nr=42 max_buffers=4 > sudo dmesg -C > ffmpeg -loglevel error -re -f lavfi -i testsrc=size=640x480:rate=30 > -t 30 \ > -f v4l2 /dev/video42 & > ffmpeg -loglevel error -f v4l2 -i /dev/video42 -t 25 -f null - > dmesg > > Both ffmpeg commands must exit 0 and dmesg must contain no "Oops", > "BUG:" or "page fault" entry. > Without the accessor fix the consumer is killed and dmesg shows the > vidioc_reqbufs page fault above. > > [Where problems could occur] > > If either compat macro is wrong, the module either stops building on > one of the two kernels noble supports, leaving apt in the broken state > this SRU is fixing, or resolves the opener incorrectly and oopses on > the first ioctl a consumer issues. > > [Other Info] > > Fixed upstream in v4l2loopback 0.15.2 by > > https://github.com/v4l2loopback/v4l2loopback/commit/3b09d3c53997f5f05e8d0db9222706585dbbe67a > Fix compilation with linux-6.18.0 > (with its follow-up ce8474158c6e, which applies the same change to > v4l2_fh_del) > > and in 0.15.3 by > > https://github.com/v4l2loopback/v4l2loopback/commit/6b33fe1f682881eb268ab9fc85f231acc5564ac8 > use linux>=6.18 accessor for v4l2->private_data > > [ORIGINAL DESCRIPTION] > > v4l2loopback.c: In function ‘v4l2_loopback_open’: > v4l2loopback.c:2089:9: error: too few arguments to function ‘v4l2_fh_add’ > 2089 | v4l2_fh_add(&opener->fh); > | ^~~~~~~~~~~ > In file included from > /usr/src/linux-headers-7.0.0-28-generic/include/media/v4l2-subdev.h:17, > from > /usr/src/linux-headers-7.0.0-28-generic/include/media/v4l2-device.h:13, > from v4l2loopback.c:31: > /usr/src/linux-headers-7.0.0-28-generic/include/media/v4l2-fh.h:97:6: > note: declared here > 97 | void v4l2_fh_add(struct v4l2_fh *fh, struct file *filp); > | ^~~~~~~~~~~ > v4l2loopback.c: In function ‘v4l2_loopback_close’: > v4l2loopback.c:2117:9: error: too few arguments to function ‘v4l2_fh_del’ > 2117 | v4l2_fh_del(&opener->fh); > | ^~~~~~~~~~~ > /usr/src/linux-headers-7.0.0-28-generic/include/media/v4l2-fh.h:125:6: > note: declared here > 125 | void v4l2_fh_del(struct v4l2_fh *fh, struct file *filp); > | ^~~~~~~~~~~ > > ProblemType: Package > DistroRelease: Ubuntu 24.04 > Package: linux-headers-7.0.0-28-generic 7.0.0-28.28~24.04.1 > ProcVersionSignature: Ubuntu 6.17.0-35.35~24.04.1-generic 6.17.13 > Uname: Linux 6.17.0-35-generic x86_64 > NonfreeKernelModules: nvidia_modeset nvidia > ApportVersion: 2.28.2-0ubuntu0.1 > Architecture: amd64 > AudioDevicesInUse: > USER PID ACCESS COMMAND > /dev/snd/controlC0: tom-brown 2572 F.... wireplumber > /dev/snd/controlC1: tom-brown 2572 F.... wireplumber > /dev/snd/seq: tom-brown 2567 F.... pipewire > CRDA: N/A > CasperMD5CheckResult: pass > Date: Thu Jul 16 22:52:40 2026 > ErrorMessage: installed linux-headers-7.0.0-28-generic package > post-installation script subprocess returned error exit status 11 > InstallationDate: Installed on 2025-12-20 (209 days ago) > InstallationMedia: Ubuntu 24.04.3 LTS "Noble Numbat" - Release amd64 > (20250805.1) > Lsusb: > Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub > Bus 001 Device 002: ID 046d:c52b Logitech, Inc. Unifying Receiver > Bus 001 Device 003: ID 8087:0a2b Intel Corp. Bluetooth wireless > interface > Bus 001 Device 004: ID 0bda:57c3 Realtek Semiconductor Corp. > Integrated_Webcam_HD > Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub > MachineType: Dell Inc. Precision 7510 > ProcFB: 0 i915drmfb > ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.17.0-35-generic > root=UUID=0cd37cd1-1382-4191-9107-b090419b644e ro quiet splash vt.handoff=7 > Python3Details: /usr/bin/python3.12, Python 3.12.3, python3-minimal, > 3.12.3-0ubuntu2.1 > PythonDetails: N/A > RelatedPackageVersions: grub-pc N/A > SourcePackage: linux-hwe-7.0 > Title: package linux-headers-7.0.0-28-generic 7.0.0-28.28~24.04.1 failed > to install/upgrade: installed linux-headers-7.0.0-28-generic package > post-installation script subprocess returned error exit status 11 > UpgradeStatus: No upgrade log present (probably fresh install) > dmi.bios.date: 03/09/2023 > dmi.bios.release: 1.31 > dmi.bios.vendor: Dell Inc. > dmi.bios.version: 1.31.3 > dmi.board.name: 0MJ7KG > dmi.board.vendor: Dell Inc. > dmi.board.version: A00 > dmi.chassis.type: 9 > dmi.chassis.vendor: Dell Inc. > dmi.modalias: > dmi:bvnDellInc.:bvr1.31.3:bd03/09/2023:br1.31:svnDellInc.:pnPrecision7510:pvr:rvnDellInc.:rn0MJ7KG:rvrA00:cvnDellInc.:ct9:cvr:sku06D9: > dmi.product.family: Precision > dmi.product.name: Precision 7510 > dmi.product.sku: 06D9 > dmi.sys.vendor: Dell Inc. > > To manage notifications about this bug go to: > > https://bugs.launchpad.net/ubuntu/+source/v4l2loopback/+bug/2161037/+subscriptions > > -- J. Thomas Brown www.jthomasbrown.com -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2161037 Title: v4l2loopback fails to build and then oopses on kernel 7.0 HWE To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/v4l2loopback/+bug/2161037/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
