I put 4.2.0-040200rc3-generic under RAM stress. I still can not get to
over 5GB (of 8GB) before kswapd turns the system unusable.
** Tags added: kernel-bug-exists-upstream
** Changed in: linux (Ubuntu)
Status: Incomplete => Confirmed
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https://bugs.launchpad.net/bugs/1476211
Title:
kswapd takes 100% CPU although there is no swap
Status in linux package in Ubuntu:
Confirmed
Bug description:
On a notebook with neither swap partition nor swap file (because of
SSD and surplus of RAM), kswapd0 suddenly runs amok and takes 100% of
CPU activity. When this happens, usually at most 5.5 of 8 GB RAM were
in use, so there is no reason to swap.
This happens so suddenly, that no user input is possible anymore, eg.
I can barely switch to tty to kill processes that take most RAM. The
processor becomes extremely hot and I can only turn the computer off
and reboot. I consider this as critical and harmful to my hardware.
I noticed that Ubuntu installs by default with swappiness 60. Now I
changed that to 10 because I would never encounter the case that 8GB
are in use, but it didn't have an effect.
Expected behavior:
- on systems without RAM, kswapd should never attempt to swap
- if there is not enough RAM, kernel should kill processes to free up RAM
- no process should be able to claim so much CPU activity, that the computer
becomes unresponsive (it should always be possible to control/stop/kill
processes over tty)
Actual behavior:
- kswapd tries to swap although there is no swap space
ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: linux-image-3.19.0-22-generic 3.19.0-22.22
ProcVersionSignature: Ubuntu 3.19.0-22.22-generic 3.19.8-ckt1
Uname: Linux 3.19.0-22-generic x86_64
ApportVersion: 2.17.2-0ubuntu1.1
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC1: andreas 2368 F.... pulseaudio
/dev/snd/controlC0: andreas 2368 F.... pulseaudio
CurrentDesktop: Unity
Date: Mon Jul 20 12:49:24 2015
EcryptfsInUse: Yes
InstallationDate: Installed on 2015-06-06 (43 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422)
MachineType: LENOVO 20266
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.19.0-22-generic
root=UUID=8a0dc2f3-fcf3-4e5b-8e23-1441bd36e3dc ro noprompt persistent quiet
splash acpi_backlight=vendor vt.handoff=7 init=/sbin/upstart
RelatedPackageVersions:
linux-restricted-modules-3.19.0-22-generic N/A
linux-backports-modules-3.19.0-22-generic N/A
linux-firmware 1.143.1
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 10/31/2013
dmi.bios.vendor: LENOVO
dmi.bios.version: 76CN31WW
dmi.board.asset.tag: No Asset Tag
dmi.board.name: Yoga2
dmi.board.vendor: LENOVO
dmi.board.version: 31900058STD
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Lenovo Yoga 2 Pro
dmi.modalias:
dmi:bvnLENOVO:bvr76CN31WW:bd10/31/2013:svnLENOVO:pn20266:pvrLenovoYoga2Pro:rvnLENOVO:rnYoga2:rvr31900058STD:cvnLENOVO:ct10:cvrLenovoYoga2Pro:
dmi.product.name: 20266
dmi.product.version: Lenovo Yoga 2 Pro
dmi.sys.vendor: LENOVO
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