Messages in this thread |  | | Date | Mon, 30 Aug 2010 10:13:13 +0100 (BST) | From | Mark Hills <> | Subject | Re: cgroup: rmdir() does not complete |
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On Fri, 27 Aug 2010, KAMEZAWA Hiroyuki wrote:
> On Fri, 27 Aug 2010 12:39:48 +0900 > Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote: > > > On Fri, 27 Aug 2010 11:35:06 +0900 > > KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote: > > > > > On Fri, 27 Aug 2010 09:56:39 +0900 > > > Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> 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 ? > on ext4. > > > And, how long does it likely to take to cause this problem ? > > very soon. 10-20 loop.
The test case I was running is similar to the above. With the Lustre filesystem the problem takes 4 hours or more to show itself. Recently I ran 4 threads for over 24 hours without it being seen -- I suspect some external factor is involved.
I also tried NFS, and did not see a problem after 8 hours or so, but this is inconclusive.
The use of the Fedora kernel, and the Lustre filesystem is not satisfactory to trace the bug. Until I can get a test case which is more readily reproducable, I'm not able to reasonably think about changing variables.
It is interesting you see the problem so readily on ext4; I will test that soon (it is currently holiday weekend in the UK). I hope it will give me the test case I am looking for.
Thanks
-- Mark
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