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Date: Sun, 20 Jun 2010 22:23:50 -0400 From: Richard Yao <shiningarcanine@...il.com> To: Andrew Hendry <andrew.hendry@...il.com> Cc: 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 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: [ 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 >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in >> the body of a message to majordomo@...r.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> Please read the FAQ at http://www.tux.org/lkml/ >> > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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