Public bug reported:

On a vps with 512MB RAM and a 2 GB swapfile, I am experiencing 100%
reproducible OOM when running duplicity.  duplicity uses a fair amount
of memory, about 300 MB at the time of OOM, but there should be plenty
of swap to accommodate it.

I have attached a syslog excerpt.  Note "Free swap  = 2004684kB".

If I am reading the log message correctly, "order=2" at the top means
this was an attempt to allocate 4 pages, i.e. 16KB.  It certainly seems
that it should be possible to satisfy this by swapping.  I know
fragmentation is a possible issue but it seems implausible that we
couldn't find 4 pages together.

This doesn't seem to happen when running other memory-hogging processes.
I wrote a small program that malloc's 1 GB and writes to all of it.  It
runs fine, even as root.  It is slow because of swapping but the oom-
killer does not get invoked.  So I am not sure what is special about
duplicity.  It's an ordinary user-space backup utility written in
Python; it reads files, encrypts data, and sends it out over ssh.  The
only thing I can think of is that it runs gpg to do the encryption, and
I believe gpg will mlock() some memory to keep keys secure, but that
should be a really small amount.

Happy to supply more information or test things.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: linux-image-4.4.0-59-generic 4.4.0-59.80
ProcVersionSignature: Ubuntu 4.4.0-59.80-generic 4.4.35
Uname: Linux 4.4.0-59-generic x86_64
AlsaDevices:
 total 0
 crw-rw---- 1 root audio 116,  1 Jan 21 19:31 seq
 crw-rw---- 1 root audio 116, 33 Jan 21 19:31 timer
AplayDevices: Error: [Errno 2] No such file or directory: 'aplay'
ApportVersion: 2.20.1-0ubuntu2.5
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:
Date: Sun Jan 29 03:37:31 2017
HibernationDevice: RESUME=UUID=7c1226a1-9254-49c2-b4e6-64d204affd15
IwConfig:
 lo        no wireless extensions.
 
 eth1      no wireless extensions.
 
 eth0      no wireless extensions.
Lspci:
 
Lsusb: Error: command ['lsusb'] failed with exit code 1:
PciMultimedia:
 
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcFB:
 
ProcKernelCmdLine: root=/dev/xvda1 ro quiet splash console=hvc0
RelatedPackageVersions:
 linux-restricted-modules-4.4.0-59-generic N/A
 linux-backports-modules-4.4.0-59-generic  N/A
 linux-firmware                            1.157.6
RfKill: Error: [Errno 2] No such file or directory: 'rfkill'
SourcePackage: linux
UpgradeStatus: Upgraded to xenial on 2016-09-19 (132 days ago)

** Affects: linux (Ubuntu)
     Importance: Undecided
         Status: Incomplete


** Tags: amd64 apport-bug xenial

** Attachment added: "syslog excerpt"
   https://bugs.launchpad.net/bugs/1660098/+attachment/4810269/+files/syslog

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https://bugs.launchpad.net/bugs/1660098

Title:
  OOM with lots of free swap

Status in linux package in Ubuntu:
  Incomplete

Bug description:
  On a vps with 512MB RAM and a 2 GB swapfile, I am experiencing 100%
  reproducible OOM when running duplicity.  duplicity uses a fair amount
  of memory, about 300 MB at the time of OOM, but there should be plenty
  of swap to accommodate it.

  I have attached a syslog excerpt.  Note "Free swap  = 2004684kB".

  If I am reading the log message correctly, "order=2" at the top means
  this was an attempt to allocate 4 pages, i.e. 16KB.  It certainly
  seems that it should be possible to satisfy this by swapping.  I know
  fragmentation is a possible issue but it seems implausible that we
  couldn't find 4 pages together.

  This doesn't seem to happen when running other memory-hogging
  processes.  I wrote a small program that malloc's 1 GB and writes to
  all of it.  It runs fine, even as root.  It is slow because of
  swapping but the oom-killer does not get invoked.  So I am not sure
  what is special about duplicity.  It's an ordinary user-space backup
  utility written in Python; it reads files, encrypts data, and sends it
  out over ssh.  The only thing I can think of is that it runs gpg to do
  the encryption, and I believe gpg will mlock() some memory to keep
  keys secure, but that should be a really small amount.

  Happy to supply more information or test things.

  ProblemType: Bug
  DistroRelease: Ubuntu 16.04
  Package: linux-image-4.4.0-59-generic 4.4.0-59.80
  ProcVersionSignature: Ubuntu 4.4.0-59.80-generic 4.4.35
  Uname: Linux 4.4.0-59-generic x86_64
  AlsaDevices:
   total 0
   crw-rw---- 1 root audio 116,  1 Jan 21 19:31 seq
   crw-rw---- 1 root audio 116, 33 Jan 21 19:31 timer
  AplayDevices: Error: [Errno 2] No such file or directory: 'aplay'
  ApportVersion: 2.20.1-0ubuntu2.5
  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:
  Date: Sun Jan 29 03:37:31 2017
  HibernationDevice: RESUME=UUID=7c1226a1-9254-49c2-b4e6-64d204affd15
  IwConfig:
   lo        no wireless extensions.
   
   eth1      no wireless extensions.
   
   eth0      no wireless extensions.
  Lspci:
   
  Lsusb: Error: command ['lsusb'] failed with exit code 1:
  PciMultimedia:
   
  ProcEnviron:
   TERM=xterm
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  ProcFB:
   
  ProcKernelCmdLine: root=/dev/xvda1 ro quiet splash console=hvc0
  RelatedPackageVersions:
   linux-restricted-modules-4.4.0-59-generic N/A
   linux-backports-modules-4.4.0-59-generic  N/A
   linux-firmware                            1.157.6
  RfKill: Error: [Errno 2] No such file or directory: 'rfkill'
  SourcePackage: linux
  UpgradeStatus: Upgraded to xenial on 2016-09-19 (132 days ago)

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