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[Bug 1518457] Re: kswapd0 100% CPU usage
I had this issue too on AWS.
In my case, it was the udev rule for vm-hotadd and the fix as mentioned
previously basically came down to "touch /etc/udev/rules.d/40-vm-
hotadd.rules" which effectively disables the /lib/udev/rules.d/40-vm-
hotadd.rules file (after a reboot).
The udev rule basically seems to only be active for Xen or Hyper-V and
while it seems the Hyper-V stuff was also present in previous versions,
the Xen stuff seems to be introduced in 15.10 or newer.
So if you're seeing this issue on anything running on Xen, including
This is probably a bug in Xen or a bug in the kernel.
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kswapd0 100% CPU usage
Status in Linux:
Status in linux package in Ubuntu:
As per bug 721896 and various others:
I'm on an AWS t2.micro instance (Xeon E5-2670, 991MiB of memory).
Occasionally (about once a day), kswapd0 falls into a busy loop and
spins on 100% CPU usage indefinitely. This can be provoked by
copying/writing large files (e.g. dding a 256MB file), but it happens
occasionally otherwise. System memory usage (not including
buffers/caches) currently sits at 36%, which is typical. Initially
I had no swap space configured; I've since tried enabling a 256MB swap
file, but the problem continues to occur and no swap space is used.
The system can be recovered with `echo 1 > /proc/sys/vm/drop_caches`.
Happy to provide further information/take further debugging actions.
 Full output from `free`:
total used free shared buffers cached
Mem: 1014936 483448 531488 28556 9756 112700
-/+ buffers/cache: 360992 653944
Swap: 262140 0 262140
DistroRelease: Ubuntu 15.10
Package: linux-image-4.2.0-18-generic 4.2.0-18.22
ProcVersionSignature: Ubuntu 4.2.0-18.22-generic 4.2.3
Uname: Linux 4.2.0-18-generic x86_64
crw-rw---- 1 root audio 116, 1 Nov 19 19:40 seq
crw-rw---- 1 root audio 116, 33 Nov 19 19:40 timer
AplayDevices: Error: [Errno 2] No such file or directory: 'aplay'
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:
Date: Fri Nov 20 20:44:30 2015
IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig'
Lsusb: Error: command ['lsusb'] failed with exit code 1: unable to initialize libusb: -99
MachineType: Xen HVM domU
PATH=(custom, no user)
ProcFB: 0 xen
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.2.0-18-generic root=UUID=35bc01f4-4602-4823-976e-508edef899df ro console=tty1 console=ttyS0 net.ifnames=0
RfKill: Error: [Errno 2] No such file or directory: 'rfkill'
UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev'
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.product.name: HVM domU
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