[Bug 1759836]

[jgwphd]

An update: The problem I reported in January went away on its own after
a few weeks of having the problem every single day when I booted each
morning. I was installing Ubuntu software updates when they became
available during that time. There is something going on during boot that
causes this problem.

"my speculation" is that I suspect a timing issue with the way things
are initialized during boot up that leads to the problem. Some strange
timing issue is occurring which causes systemd-udevd to fall into an
infinite loop (continuously looking for something or to be notified
about an action completion) and drive one of the processor cores to
100%. When a new kernel was installed or something was done to change
initialization activity during boot the problem went away because the
timing problem that created it was changed. I believe that some kind of
race condition may be at the root of the problem.

>From my earlier search on the problem symptoms, it seems that when
systemd-udevd isn't working correctly you can get numerous confusing
symptoms that mysteriously go away when the something changes timing
conditions during boot. Since the problem is in the kernel then it
effects other systems besides Ubuntu.

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https://bugs.launchpad.net/bugs/1759836

Title:
  systemd-udevd consumes 100% of CPU

Status in linux:
  Confirmed
Status in The Ubuntu Power Consumption Project:
  New
Status in bluez package in Ubuntu:
  Invalid
Status in linux package in Ubuntu:
  Incomplete
Status in systemd package in Ubuntu:
  Confirmed

Bug description:
  The systemd-udevd proccess consumes 100% of a thread everytime, but
  i'm not noticing any difference in my computer.

  ProblemType: Bug
  DistroRelease: Ubuntu 18.04
  Package: systemd 237-3ubuntu6
  ProcVersionSignature: Ubuntu 4.15.0-13.14-generic 4.15.10
  Uname: Linux 4.15.0-13-generic x86_64
  NonfreeKernelModules: wl
  ApportVersion: 2.20.9-0ubuntu2
  Architecture: amd64
  CurrentDesktop: ubuntu:GNOME
  Date: Thu Mar 29 08:52:54 2018
  InstallationDate: Installed on 2018-03-05 (23 days ago)
  InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Alpha amd64 (20180304)
  MachineType: Dell Inc. Inspiron N5010
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-13-generic root=UUID=3c29e292-f1ae-45e1-a0ed-a82524278ce1 ro quiet splash vt.handoff=1
  SourcePackage: systemd
  SystemdDelta:
   [EXTENDED]   /lib/systemd/system/rc-local.service → /lib/systemd/system/rc-local.service.d/debian.conf
   [EXTENDED]   /lib/systemd/system/user at .service → /lib/systemd/system/user at .service.d/timeout.conf

   2 overridden configuration files found.
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 01/25/2011
  dmi.bios.vendor: Dell Inc.
  dmi.bios.version: A12
  dmi.board.name: 08R0GW
  dmi.board.vendor: Dell Inc.
  dmi.board.version: A12
  dmi.chassis.type: 8
  dmi.chassis.vendor: Dell Inc.
  dmi.chassis.version: A12
  dmi.modalias: dmi:bvnDellInc.:bvrA12:bd01/25/2011:svnDellInc.:pnInspironN5010:pvrA12:rvnDellInc.:rn08R0GW:rvrA12:cvnDellInc.:ct8:cvrA12:
  dmi.product.name: Inspiron N5010
  dmi.product.version: A12
  dmi.sys.vendor: Dell Inc.

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