Subject: Re: [vserver] Resource Limit issues
From: Herbert Poetzl <herbert@13thfloor.at>
Date: Thu, 10 Mar 2011 16:28:03 +0100

On Thu, Mar 10, 2011 at 03:13:52PM +0000, Joe Gooch wrote:
> I have several servers that have run Debian Lenny w/ kernel 2.6.22.19
> for quite some time without any issues. I've been doing rolling
> upgrades to Squeeze... and I've encountered some strange limiting
> behavior.

> Some of my vservers have limits on resource usage (i.e. rlimits/as,
> rlimits/nproc, rlimits/rss), and have been experiencing out of memory
> issues to the extent that I can't even vserver exec processes into the
> namespace anymore.

> Looking at all my /proc/virtual/xxx/limit I see the following:
> VM:         73456        0/      -1         -1/      -1        0
> VM:          7264        0/      -1         -1/      -1        0
> *VM:       -27253        0/      -1         -1/      -1        0
> VM:          6751        0/      -1         -1/      -1        0
> VM:        183464        0/      -1         -1/      -1        0
> VM:       1261030        0/ 2224643         -1/      -1        0
> VM:         41791        0/  199142         -1/      -1        0
> VM:        191196        0/  258038         -1/      -1        0
> VM:        199354        0/ 1603723         -1/      -1        0
> VM:        670480        0/      -1         -1/      -1        0
> -VM:        45315        0/ 1200000    1200000/ 1200000        0
> VM:         31508        0/  300000     300000/  300000        0
> *VM:       -88860        0/      -1         -1/      -1        0
> VM:        431386        0/  502421         -1/      -1        0
> *VM:       -14804        0/      -1         -1/      -1        0
> VM:         25737        0/      -1         -1/      -1        0

> Notice have 3 vservers on different hosts that have negative "current"
> values for virtual memory. (at the moment) The ones that have no
> hard/soft limit are ok... but if I have a hard limit configured, I
> can't spawn any more processes when this happens. I have a vserver
> where this happens at least once a day. (the dashed one above)

> I would assume that a negative current value is a bug... 

definitely a bug, you might check with the mainline 2.6.32.28
kernel and appropriate patch, if you can recreate the issue
there, let me know and we'll investigate ...

> Is there a delta to fix this? 

no idea, the VM/RSS accounting and limits have been dropped
in favor to the mainline cgroup accounting which is used in
all newer kernels

> Kernel is 2.6.32-5-vserver from squeeze. (mostly 686 kernels)... 
> In looking at their deb it looks like they're using vs2.3.0.36.29.6.

best,
Herbert

> Thanks.
> Joe
>