Comment 0 for bug 1634892

Setting net.ipv4.neigh.default.gc_thresh1/2/3 on the 3.13.0-96-generic kernel and below worked fine using the following:

$ sudo /sbin/sysctl -w net.ipv4.neigh.default.gc_thresh1=128
128

As of 3.13.0-97-generic, though, it no longer works as expected:

$ sudo /sbin/sysctl -w net.ipv4.neigh.default.gc_thresh1=128
error: "Invalid argument" setting key "net.ipv4.neigh.default.gc_thresh1"

There are two potentially related revisions in the -97 release - http://kernel.ubuntu.com/git/ubuntu/ubuntu-precise.git/commit/?h=lts-backport-trusty&id=563cf19389d8e999e69d6c94995966aeaf7c3a08 and http://kernel.ubuntu.com/git/ubuntu/ubuntu-precise.git/commit/?h=lts-backport-trusty&id=7b82096b0ebc9bf487b390fe970d66ffa5a5774e.

The expected behavior is that changing neighbor table settings works fine via 'sysctl -w'.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: linux-image-3.13.0-98-generic 3.13.0-98.145~precise1
ProcVersionSignature: Ubuntu 3.13.0-98.145~precise1-generic 3.13.11-ckt39
Uname: Linux 3.13.0-98-generic x86_64
AlsaVersion: Advanced Linux Sound Architecture Driver Version k3.13.0-98-generic.
AplayDevices: Error: [Errno 2] No such file or directory
ApportVersion: 2.0.1-0ubuntu17.13
Architecture: amd64
ArecordDevices: Error: [Errno 2] No such file or directory
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/by-path', '/dev/snd/controlC0', '/dev/snd/pcmC0D0c', '/dev/snd/pcmC0D0p', '/dev/snd/pcmC0D1p', '/dev/snd/midiC0D0', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
CRDA: Error: [Errno 2] No such file or directory
Card0.Amixer.info: Error: [Errno 2] No such file or directory
Card0.Amixer.values: Error: [Errno 2] No such file or directory
CurrentDmesg: [ 4.586115] NET: Registered protocol family 40
Date: Wed Oct 19 06:13:36 2016
HibernationDevice: RESUME=UUID=d32abfeb-623f-4c11-ae4a-a7babe8c2139
InstallationMedia: Ubuntu-Server 12.04.5 LTS "Precise Pangolin" - Release amd64 (20140806.1)
IwConfig: Error: [Errno 2] No such file or directory
MachineType: VMware, Inc. VMware Virtual Platform
MarkForUpload: True
ProcEnviron:
 LANGUAGE=en_US:
 TERM=screen-256color
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcFB: 0 svgadrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-98-generic root=UUID=febea164-78c3-4d3a-a0ce-0f09990df608 ro find_preseed=/preseed.cfg noprompt quiet
RelatedPackageVersions:
 linux-restricted-modules-3.13.0-98-generic N/A
 linux-backports-modules-3.13.0-98-generic N/A
 linux-firmware 1.79.16
RfKill: Error: [Errno 2] No such file or directory
SourcePackage: linux-lts-trusty
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 07/02/2015
dmi.bios.vendor: Phoenix Technologies LTD
dmi.bios.version: 6.00
dmi.board.name: 440BX Desktop Reference Platform
dmi.board.vendor: Intel Corporation
dmi.board.version: None
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 1
dmi.chassis.vendor: No Enclosure
dmi.chassis.version: N/A
dmi.modalias: dmi:bvnPhoenixTechnologiesLTD:bvr6.00:bd07/02/2015:svnVMware,Inc.:pnVMwareVirtualPlatform:pvrNone:rvnIntelCorporation:rn440BXDesktopReferencePlatform:rvrNone:cvnNoEnclosure:ct1:cvrN/A:
dmi.product.name: VMware Virtual Platform
dmi.product.version: None
dmi.sys.vendor: VMware, Inc.