Public bug reported: Install a new Ubuntu 22.04 Jammy system and run the following commands in a bash shell:
sudo -i apt-get update && apt-get install -y iproute2 # often not necessary depmod -a modprobe ifb numifbs=1 ip link add ifb0 type ifb ip link set dev ifb0 up tc qdisc add dev lo ingress tc filter add dev lo parent ffff: protocol ip u32 match u32 0 0 action mirred egress redirect dev ifb0 tc qdisc add dev lo root handle 1: htb tc qdisc add dev ifb0 root handle 1: htb direct_qlen 1000 echo "next command may lock up" tc qdisc add dev ifb0 parent 1:1 handle 10: netem limit 100 delay 100ms 20ms distribution normal and you will see tc's CPU usage go to 100% and soon after the entire system will lock up. tc in this state cannot be killed, even with kill -9. This happens on the October 10th version https://cloud-images.ubuntu.com/jammy/20231010/jammy-server-cloudimg-amd64.ova, which has kernel version 5.15.0-86-generic. It does not happen on the previous version https://cloud-images.ubuntu.com/jammy/20230929/jammy-server-cloudimg-amd64.ova, which has kernel version 5.15.0-84-generic. On the 5.15.0-84-generic version, the final TC command gives an error "Error: Specified class not found.". This is not seen on the "5.15.0-86-generic" version. Therefore I believe this is a regression between these two kernel versions 5.15.0-84 and 5.15.0-86. The tc binary is identical and the iproute2 library has the same version on both installations. ProblemType: Bug DistroRelease: Ubuntu 22.04 Package: linux-image-5.15.0-86-generic 5.15.0-86.96 ProcVersionSignature: Ubuntu 5.15.0-86.96-generic 5.15.122 Uname: Linux 5.15.0-86-generic x86_64 AlsaDevices: total 0 crw-rw---- 1 root audio 116, 1 Oct 11 17:07 seq crw-rw---- 1 root audio 116, 33 Oct 11 17:07 timer AplayDevices: Error: [Errno 2] No such file or directory: 'aplay' ApportVersion: 2.20.11-0ubuntu82.5 Architecture: amd64 ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord' AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1: CRDA: N/A CasperMD5CheckResult: unknown CloudArchitecture: x86_64 CloudID: ovf CloudName: ovf CloudPlatform: ovf CloudSubPlatform: ovf (iso) Date: Wed Oct 11 17:14:39 2023 IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig' Lsusb: Error: command ['lsusb'] failed with exit code 1: Lsusb-t: Lsusb-v: Error: command ['lsusb', '-v'] failed with exit code 1: MachineType: VMware, Inc. VMware Virtual Platform PciMultimedia: ProcEnviron: TERM=vt100 PATH=(custom, no user) LANG=C.UTF-8 SHELL=/bin/bash ProcFB: 0 svgadrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.15.0-86-generic root=LABEL=cloudimg-rootfs ro console=tty1 console=ttyS0 RelatedPackageVersions: linux-restricted-modules-5.15.0-86-generic N/A linux-backports-modules-5.15.0-86-generic N/A linux-firmware N/A RfKill: Error: [Errno 2] No such file or directory: 'rfkill' SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 12/12/2018 dmi.bios.release: 4.6 dmi.bios.vendor: Phoenix Technologies LTD dmi.bios.version: 6.00 dmi.board.name: 440BX Desktop Reference Platform dmi.board.vendor: Intel Corporation dmi.board.version: None dmi.chassis.asset.tag: No Asset Tag dmi.chassis.type: 1 dmi.chassis.vendor: No Enclosure dmi.chassis.version: N/A dmi.ec.firmware.release: 0.0 dmi.modalias: dmi:bvnPhoenixTechnologiesLTD:bvr6.00:bd12/12/2018:br4.6:efr0.0:svnVMware,Inc.:pnVMwareVirtualPlatform:pvrNone:rvnIntelCorporation:rn440BXDesktopReferencePlatform:rvrNone:cvnNoEnclosure:ct1:cvrN/A:sku: dmi.product.name: VMware Virtual Platform dmi.product.version: None dmi.sys.vendor: VMware, Inc. ** Affects: linux (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-bug jammy uec-images -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/2039173 Title: tc goes to 100% CPU and locks up the system on recent 5.15 kernels Status in linux package in Ubuntu: New Bug description: Install a new Ubuntu 22.04 Jammy system and run the following commands in a bash shell: sudo -i apt-get update && apt-get install -y iproute2 # often not necessary depmod -a modprobe ifb numifbs=1 ip link add ifb0 type ifb ip link set dev ifb0 up tc qdisc add dev lo ingress tc filter add dev lo parent ffff: protocol ip u32 match u32 0 0 action mirred egress redirect dev ifb0 tc qdisc add dev lo root handle 1: htb tc qdisc add dev ifb0 root handle 1: htb direct_qlen 1000 echo "next command may lock up" tc qdisc add dev ifb0 parent 1:1 handle 10: netem limit 100 delay 100ms 20ms distribution normal and you will see tc's CPU usage go to 100% and soon after the entire system will lock up. tc in this state cannot be killed, even with kill -9. This happens on the October 10th version https://cloud-images.ubuntu.com/jammy/20231010/jammy-server-cloudimg-amd64.ova, which has kernel version 5.15.0-86-generic. It does not happen on the previous version https://cloud-images.ubuntu.com/jammy/20230929/jammy-server-cloudimg-amd64.ova, which has kernel version 5.15.0-84-generic. On the 5.15.0-84-generic version, the final TC command gives an error "Error: Specified class not found.". This is not seen on the "5.15.0-86-generic" version. Therefore I believe this is a regression between these two kernel versions 5.15.0-84 and 5.15.0-86. The tc binary is identical and the iproute2 library has the same version on both installations. ProblemType: Bug DistroRelease: Ubuntu 22.04 Package: linux-image-5.15.0-86-generic 5.15.0-86.96 ProcVersionSignature: Ubuntu 5.15.0-86.96-generic 5.15.122 Uname: Linux 5.15.0-86-generic x86_64 AlsaDevices: total 0 crw-rw---- 1 root audio 116, 1 Oct 11 17:07 seq crw-rw---- 1 root audio 116, 33 Oct 11 17:07 timer AplayDevices: Error: [Errno 2] No such file or directory: 'aplay' ApportVersion: 2.20.11-0ubuntu82.5 Architecture: amd64 ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord' AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1: CRDA: N/A CasperMD5CheckResult: unknown CloudArchitecture: x86_64 CloudID: ovf CloudName: ovf CloudPlatform: ovf CloudSubPlatform: ovf (iso) Date: Wed Oct 11 17:14:39 2023 IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig' Lsusb: Error: command ['lsusb'] failed with exit code 1: Lsusb-t: Lsusb-v: Error: command ['lsusb', '-v'] failed with exit code 1: MachineType: VMware, Inc. VMware Virtual Platform PciMultimedia: ProcEnviron: TERM=vt100 PATH=(custom, no user) LANG=C.UTF-8 SHELL=/bin/bash ProcFB: 0 svgadrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.15.0-86-generic root=LABEL=cloudimg-rootfs ro console=tty1 console=ttyS0 RelatedPackageVersions: linux-restricted-modules-5.15.0-86-generic N/A linux-backports-modules-5.15.0-86-generic N/A linux-firmware N/A RfKill: Error: [Errno 2] No such file or directory: 'rfkill' SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 12/12/2018 dmi.bios.release: 4.6 dmi.bios.vendor: Phoenix Technologies LTD dmi.bios.version: 6.00 dmi.board.name: 440BX Desktop Reference Platform dmi.board.vendor: Intel Corporation dmi.board.version: None dmi.chassis.asset.tag: No Asset Tag dmi.chassis.type: 1 dmi.chassis.vendor: No Enclosure dmi.chassis.version: N/A dmi.ec.firmware.release: 0.0 dmi.modalias: dmi:bvnPhoenixTechnologiesLTD:bvr6.00:bd12/12/2018:br4.6:efr0.0:svnVMware,Inc.:pnVMwareVirtualPlatform:pvrNone:rvnIntelCorporation:rn440BXDesktopReferencePlatform:rvrNone:cvnNoEnclosure:ct1:cvrN/A:sku: dmi.product.name: VMware Virtual Platform dmi.product.version: None dmi.sys.vendor: VMware, Inc. 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