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. Changes from v2 o added [patch 1/5] use euid instead of CAP_SYS_ADMIN KOSAKI Motohiro (6): oom: use euid instead of CAP_SYS_ADMIN for protection root process 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 | 5 +- include/linux/sched.h | 11 +++ mm/oom_kill.c | 201 ++++++++++++++++++++++++++---------------------- 4 files changed, 131 insertions(+), 99 deletions(-) -- 1.7.3.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>