Comment 0 for bug 1788018

It first appeared when I upgraded ubuntu studio to 18.04
udevd started to use all available cpu.
now I'm running ubuntu desktop from a usb key and it's still the same

udevadm monitor returns:
KERNEL[2512.539491] unbind /devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.1/1-1.1.2/1-1.1.2:1.0 (usb)
UDEV [2512.540201] bind /devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.1/1-1.1.2/1-1.1.2:1.0 (usb)
KERNEL[2512.566574] bind /devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.1/1-1.1.2/1-1.1.2:1.0 (usb)
KERNEL[2512.566866] unbind /devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.1/1-1.1.2/1-1.1.2:1.0 (usb)
UDEV [2512.567499] unbind /devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.1/1-1.1.2/1-1.1.2:1.0 (usb)
KERNEL[2512.594050] bind /devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.1/1-1.1.2/1-1.1.2:1.0 (usb)
KERNEL[2512.594310] unbind /devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.1/1-1.1.2/1-1.1.2:1.0 (usb)
UDEV [2512.596510] bind /devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.1/1-1.1.2/1-1.1.2:1.0 (usb)
KERNEL[2512.620736] bind /devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.1/1-1.1.2/1-1.1.2:1.0 (usb)
KERNEL[2512.624606] unbind /devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.1/1-1.1.2/1-1.1.2:1.0 (usb)
UDEV [2512.634706] unbind /devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.1/1-1.1.2/1-1.1.2:1.0 (usb)
...

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: udev 237-3ubuntu10.3
ProcVersionSignature: Ubuntu 4.15.0-29.31-generic 4.15.18
Uname: Linux 4.15.0-29-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.2
Architecture: amd64
CasperVersion: 1.394
CustomUdevRuleFiles: 70-snap.core.rules
Date: Mon Aug 20 18:54:48 2018
ExecutablePath: /lib/systemd/systemd-udevd
LiveMediaBuild: Ubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
MachineType: Dell Inc. Vostro 3300
ProcEnviron:
 LANG=C.UTF-8
 PATH=(custom, no user)
ProcKernelCmdLine: file=/cdrom/preseed/hostname.seed boot=casper initrd=/casper/initrd.lz quiet splash --- maybe-ubiquity
SourcePackage: systemd
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 02/10/2010
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A01
dmi.board.name: 07JC8T
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 8
dmi.chassis.vendor: Dell Inc.
dmi.chassis.version: Not Specified
dmi.modalias: dmi:bvnDellInc.:bvrA01:bd02/10/2010:svnDellInc.:pnVostro3300:pvrNotSpecified:rvnDellInc.:rn07JC8T:rvrA00:cvnDellInc.:ct8:cvrNotSpecified:
dmi.product.name: Vostro 3300
dmi.product.version: Not Specified
dmi.sys.vendor: Dell Inc.