Ubuntu
linux package

out of memory errors when performing I/O on a system with large amount of RAM and 32-bit pae kernel

Bug #1098342 reported by Iordan Iordanov on 2013-01-10

This bug affects 1 person

Affects		Status	Importance	Assigned to	Milestone
	linux (Ubuntu)	Expired	Medium	Unassigned

Bug Description

We have a system with 64GB of RAM which we have to run with a 32-bit installation for various reasons. When performing I/O on that system, we suddenly get "Out of memory" errors, and if I/O is fast enough (i.e. cat /dev/zero > /dev/shm/somefile), the system becomes unusable very quickly. The following list of example commands will cause an OOM condition at various speeds:

# Causes OOM and complete denial of service within 10-15 seconds:
cat /dev/zero > /dev/shm/somefile

# Causes OOM and complete denial of service within 30 - 40 seconds:
cat /dev/zero > /dev/shm

# Causes sporadic OOM errors:
cat /dev/sda > /dev/sdb

The /dev/sda and /dev/sdb devices read and write sequentially at about 150MB/s.

The same error was reproduced with the newest upstream 32-bit pae kernels from 12.10 (quantal) and 13.04 (raring). Also, the same was reproduced with Debian Queeze 32-bit kernel (2.6.32) installed on Ubuntu 12.04.

The error appears to be absent in 64-bit kernels (installed instead of the 32-bit kernel on the same 32-bit Ubuntu 12.04 installation).

Please see attached an example of OOM and DoS that was caused with "cat /dev/shm > /dev/shm/somefile" in the out_of_memory_errors.txt attachment.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: linux-image-3.2.0-35-generic-pae 3.2.0-35.55
ProcVersionSignature: Ubuntu 3.2.0-35.55-generic-pae 3.2.34
Uname: Linux 3.2.0-35-generic-pae i686
AlsaDevices:
total 0
crw-rw---T 1 root audio 116, 1 Jan 10 15:55 seq
crw-rw---T 1 root audio 116, 33 Jan 10 15:55 timer
AplayDevices: aplay: device_list:252: no soundcards found...
ApportVersion: 2.0.1-0ubuntu14
Architecture: i386
ArecordDevices: arecord: device_list:252: no soundcards found...
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
CRDA: Error: command ['iw', 'reg', 'get'] failed with exit code 1: nl80211 not found.
CurrentDmesg:
[ 11.884916] NFSD: starting 90-second grace period
[ 18.448013] eth0: no IPv6 routers present
Date: Thu Jan 10 16:10:40 2013
IwConfig: Error: [Errno 2] No such file or directory
MachineType: Supermicro H8DGU
PciMultimedia:

ProcEnviron:
TERM=xterm
PATH=(custom, no user)
SHELL=/bin/bash
ProcFB:

ProcKernelCmdLine: root=/dev/sda1 ro
PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon.
RelatedPackageVersions:
linux-restricted-modules-3.2.0-35-generic-pae N/A
linux-backports-modules-3.2.0-35-generic-pae N/A
linux-firmware 1.79.1
RfKill: Error: [Errno 2] No such file or directory
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
WifiSyslog:

dmi.bios.date: 12/10/10
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 1.1
dmi.board.asset.tag: To Be Filled By O.E.M.
dmi.board.name: H8DGU
dmi.board.vendor: Supermicro
dmi.board.version: 1234567890
dmi.chassis.asset.tag: To Be Filled By O.E.M.
dmi.chassis.type: 17
dmi.chassis.vendor: Supermicro
dmi.chassis.version: 1234567890
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr1.1:bd12/10/10:svnSupermicro:pnH8DGU:pvr1234567890:rvnSupermicro:rnH8DGU:rvr1234567890:cvnSupermicro:ct17:cvr1234567890:
dmi.product.name: H8DGU
dmi.product.version: 1234567890
dmi.sys.vendor: Supermicro

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