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Date: Mon, 21 Jun 2010 12:03:37 +1000
Message-ID: <AANLkTikPAdDuUb37-GPDzFugBYEWNpoSLabcl2Fyt5VY@mail.gmail.com>
Subject: Re: Kernel does strange things when compilations push memory usage 
	above physical memory and the compilations are being done in a tmpfs, despite 
	having ample swap
From: Andrew Hendry <andrew.hendry@gmail.com>
To: Richard Yao <shiningarcanine@gmail.com>
Cc: linux-kernel@vger.kernel.org
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After the oom killer has killed things, is your system still really
sluggish if it doesn't lockup?

I have what might be a similar issue, after a lot of compiling on a ramdisk.
http://marc.info/?l=linux-kernel&m=127569877714937&w=2

Oom killer keeps killing processes until almost nothing is left.
Free memory is very high, and system is still very sluggish.

On Mon, Jun 21, 2010 at 10:21 AM, Richard Yao <shiningarcanine@gmail.com> wrote:
> Dear Everyone,
>
> My desktop has 4GB of RAM and it is running an unpatched Linux 2.6.34
> kernel. I recently migrated it from Windows 7 to Gentoo Linux and I am
> encountering a highly peculiar problem when I build/rebuild system
> packages in a manner that stresses memory.
>
> When system memory usage exceeds 4GB because I have several
> compilations running simultaneously, all of which have had -j5 passed
> to make, with the build scripts sharing an 8GB tmpfs directory, the
> system typically responds by activating the kernel oom-killer, which
> will usually kill some of the processes involved in the compilations,
> among other things. This is with an 8GB swap partition and barely any
> of it is touched when this happens according to KDE's system monitor.
> Rarer, but alternative responses that the system has made to such
> circumstances involve the system package manager failing
> mid-compilation with "Segmentation fault" printed to the console or
> open office failing with an obscure error message. Usually just
> compiling open office alone is enough to have things fail, although I
> usually see it fail with an obscure 5 digit error message that has no
> meaning which I can derive from doing searches with Google. Unmounting
> my tmpfs directory and doing things as I normally would do them makes
> these issues disappear.
>
> I have run memtest and it has not detected any hardware issues. I
> tried asking for help on the Gentoo Linux forums, but I received no
> responses and this looks like a kernel issue, so I thought it would be
> a good idea to ask for assistance on the kernel mailing list. Here is
> a link to a copy of my kernel's .config file:
>
> http://paste.pocoo.org/show/227799/
>
> As I was typing this, I had openoffice 3.2.1 and something else
> compiling in the background and the system completely froze. This is
> the first I have seen my system do this and it was about 10 minutes
> after the oom-killer had already taken out kwin and several tabs in
> chromium. I had SSH running in the background, but even that has been
> rendered inaccessible by the freeze. I cannot get a response from the
> system via arping and nmap is telling me that the system is down.
>
> Earlier today, I tried to reproduce this issue under simpler
> cirumstances by doing dd bs=4096 count=2097152 if=/dev/zero
> of=/var/tmp/portage/zero.bak. As a consequence of all of the swapping
> that occurred, the system's X server become unresponsive, so I walked
> away and came back a few minutes later to find that the KDE System
> Monitor had crashed, but everything else seemed fine.
>
> Any help with this issue would be appreciated. I am willing to
> recompile my system in whatever manner necessary to diagnose the cause
> of this issue. Please CC me any responses made either directly or
> indirectly in response to this message.
>
> Yours truly,
> Richard Yao
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