Message-Id: <20100621120256.8d2a2fca.kamezawa.hiroyu@jp.fujitsu.com>
Date:	Mon, 21 Jun 2010 12:02:56 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Richard Yao <shiningarcanine@...il.com>
Cc:	Andrew Hendry <andrew.hendry@...il.com>,
	linux-kernel@...r.kernel.org
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

On Sun, 20 Jun 2010 22:23:50 -0400
Richard Yao <shiningarcanine@...il.com> wrote:

> My system is still responsive if it has not locked-up, even after the
> oom-killer appears to have killed stuff.
> 
> Does the kernel need to be compiled with any special options to have
> it report to dmesg that the oom-killer activated? I cited the
> oom-killer as being activated because several things would
> inexplicit-ably crash when the system is under memory pressure, but
> looking in my dmesg log at a crash that occurred earlier today when I
> forgot to unmount my tmpfs, I do not see any references to the oom
> killer, just the process that crashed:
> 

Are your oom-killer happens  on workload on tmpfs ?
(I thought /var/tmp isn' tmpfs..)

plz check this.
=
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=d6da1a5abc2bf3a06a5bda08e0f6833409234666
=

Does oom-killer happens also on 2.6.33 ?

Thanks,
=Kame

> [ 5873.816211] chrome[18404]: segfault at 8 ip 0000000001063b9b sp
> 00007fffb0a7f540 error 4 in chrome[400000+28be000]
> 
> Could it be that a bug is causing the kernel to map the same region of
> physical memory to multiple programs?
> 
> On Sun, Jun 20, 2010 at 10:03 PM, Andrew Hendry <andrew.hendry@...il.com> wrote:
> > 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@...il.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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