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Update: Sadly not fixed for my Home Servers:

top - 19:19:36 up 45 min,  1 user,  load average: 3,95, 3,81, 3,46
Aufgaben: 175 total,   4 running, 171 sleeping,   0 stopped,   0 zombie
%Cpu(s):  1,0 be, 44,8 sy,  1,8 ni, 14,3 un, 37,6 wa,  0,0 hi,  0,5 si,  0,0 st
KiB Mem:   1872072 total,  1847332 used,    24740 free,     7704 buffers
KiB Swap:  5130332 total,    75924 used,  5054408 free.  1048580 cached Mem

  PID BENUTZER  PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND
   39 root      20   0       0      0      0 R  92,4  0,0  35:48.75 kswapd0
 2243 root      20   0       0      0      0 S   5,8  0,0   0:29.69 kworker/u4:1
 2315 root      39  19 2367016 455472   6272 S   5,8 24,3   1:44.55 java
    1 root      20   0   37832   3808   1828 S   0,0  0,2   0:01.92 systemd
    2 root      20   0       0      0      0 S   0,0  0,0   0:00.00 kthreadd
    3 root      20   0       0      0      0 S   0,0  0,0   0:04.14 ksoftirqd/0
    5 root       0 -20       0      0      0 S   0,0  0,0   0:00.00 kworker/0:0H
    7 root      20   0       0      0      0 S   0,0  0,0   0:02.52 rcu_sched
    8 root      20   0       0      0      0 S   0,0  0,0   0:00.00 rcu_bh
    9 root      20   0       0      0      0 R   0,0  0,0   0:02.38 rcuos/0
   10 root      20   0       0      0      0 S   0,0  0,0   0:00.00 rcuob/0

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https://bugs.launchpad.net/bugs/1518457

Title:
  kswapd0 100% CPU usage

Status in linux package in Ubuntu:
  In Progress

Bug description:
  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[1]. 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.

  
  [1] 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

  ProblemType: Bug
  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
  AlsaDevices:
   total 0
   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'
  ApportVersion: 2.19.1-0ubuntu5
  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
  Date: Fri Nov 20 20:44:30 2015
  Ec2AMI: ami-1c552a76
  Ec2AMIManifest: (unknown)
  Ec2AvailabilityZone: us-east-1d
  Ec2InstanceType: t2.micro
  Ec2Kernel: unavailable
  Ec2Ramdisk: unavailable
  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
  PciMultimedia:
   
  ProcEnviron:
   TERM=screen
   PATH=(custom, no user)
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  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
  RelatedPackageVersions:
   linux-restricted-modules-4.2.0-18-generic N/A
   linux-backports-modules-4.2.0-18-generic  N/A
   linux-firmware                            N/A
  RfKill: Error: [Errno 2] No such file or directory: 'rfkill'
  SourcePackage: linux
  UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev'
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 05/06/2015
  dmi.bios.vendor: Xen
  dmi.bios.version: 4.2.amazon
  dmi.chassis.type: 1
  dmi.chassis.vendor: Xen
  dmi.modalias: dmi:bvnXen:bvr4.2.amazon:bd05/06/2015:svnXen:pnHVMdomU:pvr4.2.amazon:cvnXen:ct1:cvr:
  dmi.product.name: HVM domU
  dmi.product.version: 4.2.amazon
  dmi.sys.vendor: Xen

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