Re: cgroup: rmdir() does not complete

From: Mark Hills
Date: Thu Sep 09 2010 - 07:37:02 EST


On Thu, 9 Sep 2010, Balbir Singh wrote:

> * Mark Hills <mark@xxxxxxxxxxx> [2010-09-09 11:01:45]:
>
> > On Thu, 2 Sep 2010, KAMEZAWA Hiroyuki wrote:
> >
> > [...]
> > > But hmm...it's curious who holds mutex and what happens.
> >
> > I have a system showing the failure case (but still do not have a way to
> > reliably repeat it)
> >
> > Here are the two processes:
> >
> > 23586 pts/0 RL+ 5059:18 /net/homes/mhills/tmp/soaked-cgroup
> > 23685 pts/6 DL+ 0:00 /net/homes/mhills/tmp/soaked-cgroup
> >
> > 23586 spends almost all of its time in 'RL+' status, occasionally it is
> > seen in 'DL+' status.
> >
> > From my analysis before, both are blocked on rmdir(), but one is spinning,
> > holding the lock on the /cgroup, and the other is waiting for the lock. If
> > I strace 23586 then the rmdir() fails with EINTR.
> >
>
> Any chance you can compile with debug cgroup subsystem and get
> information from there?

I can, I'd like to experiment with a custom kernel next.

I am still finding the problem incredibly hard to reproduce, so I'd like
to observe as much data as possible from the current case before
rebooting. If I could capture some kind of stack trace in the kernel for
the running process that would be great, any suggestions appreciated.

Thanks

--
Mark
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