linux-kernel - Re: [PATCH v2 0/5] Fix oom killer doesn't work at all if system have

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Date:	Mon, 30 May 2011 21:33:02 -0400 (EDT)
From:	CAI Qian <caiqian@...hat.com>
To:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org, rientjes@...gle.com, hughd@...gle.com,
	kamezawa hiroyu <kamezawa.hiroyu@...fujitsu.com>,
	minchan kim <minchan.kim@...il.com>, oleg@...hat.com
Subject: Re: [PATCH v2 0/5] Fix oom killer doesn't work at all if system
 have > gigabytes memory  (aka CAI founded issue)

Hello,

Have tested those patches rebased from KOSAKI for the latest mainline.
It still killed random processes and recevied a panic at the end by
using root user. The full oom output can be found here.
http://people.redhat.com/qcai/oom

Cheers,
CAI Qian

----- Original Message -----
> CAI Qian reported current oom logic doesn't work at all on his 16GB
> RAM
> machine. oom killer killed all system daemon at first and his system
> stopped responding.
> 
> The brief log is below.
> 
> > Out of memory: Kill process 1175 (dhclient) score 1 or sacrifice
> > child
> > Out of memory: Kill process 1247 (rsyslogd) score 1 or sacrifice
> > child
> > Out of memory: Kill process 1284 (irqbalance) score 1 or sacrifice
> > child
> > Out of memory: Kill process 1303 (rpcbind) score 1 or sacrifice
> > child
> > Out of memory: Kill process 1321 (rpc.statd) score 1 or sacrifice
> > child
> > Out of memory: Kill process 1333 (mdadm) score 1 or sacrifice child
> > Out of memory: Kill process 1365 (rpc.idmapd) score 1 or sacrifice
> > child
> > Out of memory: Kill process 1403 (dbus-daemon) score 1 or sacrifice
> > child
> > Out of memory: Kill process 1438 (acpid) score 1 or sacrifice child
> > Out of memory: Kill process 1447 (hald) score 1 or sacrifice child
> > Out of memory: Kill process 1447 (hald) score 1 or sacrifice child
> > Out of memory: Kill process 1487 (hald-addon-inpu) score 1 or
> > sacrifice child
> > Out of memory: Kill process 1488 (hald-addon-acpi) score 1 or
> > sacrifice child
> > Out of memory: Kill process 1507 (automount) score 1 or sacrifice
> > child
> 
> 
> The problems are three.
> 
> 1) if two processes have the same oom score, we should kill younger
> process.
> but current logic kill older. Typically oldest processes are system
> daemons.
> 2) Current logic use 'unsigned int' for internal score calculation.
> (exactly says,
> it only use 0-1000 value). its very low precision calculation makes a
> lot of
> same oom score and kill an ineligible process.
> 3) Current logic give 3% of SystemRAM to root processes. It obviously
> too big
> if you have plenty memory. Now, your fork-bomb processes have 500MB
> OOM immune
> bonus. then your fork-bomb never ever be killed.
> 
> 
> KOSAKI Motohiro (5):
> oom: improve dump_tasks() show items
> oom: kill younger process first
> oom: oom-killer don't use proportion of system-ram internally
> oom: don't kill random process
> oom: merge oom_kill_process() with oom_kill_task()
> 
> fs/proc/base.c | 13 ++-
> include/linux/oom.h | 10 +--
> include/linux/sched.h | 11 +++
> mm/oom_kill.c | 201 +++++++++++++++++++++++++++----------------------
> 4 files changed, 135 insertions(+), 100 deletions(-)
> 
> --
> 1.7.3.1
> 
> 
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