Re: cgroup: rmdir() does not complete

From: Daisuke Nishimura
Date: Thu Aug 26 2010 - 23:41:49 EST


On Fri, 27 Aug 2010 11:35:06 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:

> On Fri, 27 Aug 2010 09:56:39 +0900
> Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx> wrote:
>
> > > Or is it likely to be some other cause, and how best to find it?
> > >
> > What cgroup subsystem did you mount where the directory existed you tried
> > to rmdir() first ?
> > If you mounted several subsystems on the same hierarchy, can you mount them
> > separately to narrow down the cause ?
> >
>
> It seems I can reproduce the issue on mmotm-0811, too.
>
> try this.
>
> Here, memory cgroup is mounted at /cgroups.
> ==
> #!/bin/bash -x
>
> while sleep 1; do
> date
> mkdir /cgroups/test
> echo 0 > /cgroups/test/tasks
> echo 300M > /cgroups/test/memory.limit_in_bytes
> cat /proc/self/cgroup
> dd if=/dev/zero of=./tmpfile bs=4096 count=100000
> echo 0 > /cgroups/tasks
> cat /proc/self/cgroup
> rmdir /cgroups/test
> rm ./tmpfile
> done
> ==
>
> hangs at rmdir. I'm no investigating force_empty.
>
Thank you very much for your information.

Some questions.

Is "tmpfile" created on a normal filesystem(e.g. ext3) or tmpfs ?
And, how long does it likely to take to cause this problem ?
I've run it on RHEL6-based kernel/ext3 for about one hour, but
I cannot reproduce it yet.


Thanks,
Daisuke Nishimura.
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