[rhelv6-list] Setting overcommit_memory=2 kills system

[Brian Long (brilong)]

On May 17, 2012, at 3:08 PM, Michael Coffman wrote:
> In general I am in the habit of turning off memory overcommit because I believe it's a bad thing in a multi-user environment.   This was never a problem on rhel5 systems, but on rhel6, I am having issues.    When I try to set overcommit_memory=2, my system locks up.   It basically behaves as if the memory is all used up...   I see the same behavior on centos6 or rhel6.
[snip]
> One last point.   If I set the overcommit values in /etc/sysctl.conf and then reboot, the values get set correctly on boot and everything seems fine.   In addition I can then change the value of overcommit_memory to 0 and back to 2 with out any ill affects.

Just to clarify, if you set this in sysctl.conf and reboot, you're fine.  It's only if you try setting this on-the-fly that the system borks.

If this is true, it sounds like you don't have a problem for production systems.  You set up /etc/sysctl.conf in your kickstart and never worry about it, right?

Are you just curious on why you cannot do this on-the-fly?

/Brian/