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[Brad Figg <brad.figg@xxxxxxxxxxxxx>]

This bug is awaiting verification that the kernel in -proposed solves
the problem. Please test the kernel and update this bug with the
results. If the problem is solved, change the tag 'verification-needed-
quantal' to 'verification-done-quantal'.

If verification is not done by 5 working days from today, this fix will
be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how
to enable and use -proposed. Thank you!


** Tags added: verification-needed-quantal

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https://bugs.launchpad.net/bugs/1088433

Title:
  PERCPU: allocation failed when loading module kvm

Status in “linux” package in Ubuntu:
  Fix Released
Status in “linux” source package in Quantal:
  In Progress
Status in “linux” source package in Raring:
  Fix Released

Bug description:
  SRU Justification:
  Impact: When using VMs with many CPUs on kvm, the module is loaded per CPU which can cause allocation failures.

  Fix: 8d8022e8aba85192e937f1f0f7450e256d66ae5c solves the issue which
  is present in 3.8 series and beyond.

  Testcase: Boot a VM with many CPUs, reboot and check if issue occurs.

  --

  The kernel tries to load the KVM module for each CPU even though it
  really only needs to be loaded once. For each subsequent load, the
  kernel is trying to allocate the per-cpu area before it checks if the
  module is loaded already. This can result in the following backtrace:

  [    8.294573] PERCPU: allocation failed, size=304 align=32, alloc from reserved chunk failed
  [    8.294578] Pid: 1490, comm: modprobe Not tainted 3.5.0-20-generic #31-Ubuntu
  [    8.294579] Call Trace:
  [    8.294597]  [<ffffffff81143924>] pcpu_alloc+0x974/0x9d0
  [    8.294604]  [<ffffffff810b185a>] ? each_symbol_section+0x2a/0x70
  [    8.294607]  [<ffffffff810b18d1>] ? find_symbol+0x31/0x70
  [    8.294610]  [<ffffffff81143c43>] __alloc_reserved_percpu+0x13/0x20
  [    8.294613]  [<ffffffff810b413a>] layout_and_allocate+0x2fa/0xaf0
  [    8.294615]  [<ffffffff810b4a29>] load_module+0xf9/0x1170
  [    8.294630]  [<ffffffff810b5af2>] sys_init_module+0x52/0x230
  [    8.294640]  [<ffffffff8168b969>] system_call_fastpath+0x16/0x1b
  [    8.294642] kvm: Could not allocate 304 bytes percpu data

  Reproduced with kernel from quantal-release and quantal-proposed

  I found this reference on LKML:

  https://lkml.org/lkml/2012/10/11/198

  The following patch solves the issue:
  8d8022e8aba85192e937f1f0f7450e256d66ae5c
  This is in 3.8/3.11
  https://lkml.org/lkml/2013/7/11/545

  -

  ProblemType: Bug
  DistroRelease: Ubuntu 12.10
  Package: linux-image-3.5.0-20-generic 3.5.0-20.31
  ProcVersionSignature: Ubuntu 3.5.0-20.31-generic 3.5.7.1
  Uname: Linux 3.5.0-20-generic x86_64
  AlsaDevices:
   total 0
   crw-rw---T 1 root audio 116,  1 Dec 10 10:54 seq
   crw-rw---T 1 root audio 116, 33 Dec 10 10:54 timer
  AplayDevices: Error: [Errno 2] No such file or directory: 'aplay'
  ApportVersion: 2.6.1-0ubuntu6
  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: Error: [Errno 2] No such file or directory: 'iw'
  Date: Mon Dec 10 11:03:33 2012
  HibernationDevice: RESUME=UUID=c595dd75-dab5-4fcd-a089-302addcaef96
  IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig'
  MachineType: Intel Corporation LH Pass
  MarkForUpload: True
  PciMultimedia:

  ProcEnviron:
   LANGUAGE=en_US:
   TERM=screen-bce
   PATH=(custom, no user)
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  ProcFB: 0 VESA VGA
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.5.0-20-generic root=UUID=58f9a800-2e0c-4da5-9d94-c4bb4bed4fa2 ro quiet
  RelatedPackageVersions:
   linux-restricted-modules-3.5.0-20-generic N/A
   linux-backports-modules-3.5.0-20-generic  N/A
   linux-firmware                            1.95
  RfKill: Error: [Errno 2] No such file or directory: 'rfkill'
  SourcePackage: linux
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 04/30/2012
  dmi.bios.vendor: Intel Corp.
  dmi.bios.version: SE5C600.86B.99.99.2050.043020121425
  dmi.board.asset.tag: ....................
  dmi.board.name: S4600LH....
  dmi.board.vendor: Intel Corporation
  dmi.board.version: ..........
  dmi.chassis.asset.tag: ....................
  dmi.chassis.type: 23
  dmi.chassis.vendor: ...............................
  dmi.chassis.version: ..................
  dmi.modalias: dmi:bvnIntelCorp.:bvrSE5C600.86B.99.99.2050.043020121425:bd04/30/2012:svnIntelCorporation:pnLHPass:pvr....................:rvnIntelCorporation:rnS4600LH....:rvr..........:cvn...............................:ct23:cvr..................:
  dmi.product.name: LH Pass
  dmi.product.version: ....................
  dmi.sys.vendor: Intel Corporation

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