Quoting Qiang Huang (h.huangqi...@huawei.com):
> On 2013/5/24 20:49, Serge Hallyn wrote:
> > Quoting Qiang Huang (h.huangqi...@huawei.com):
> >> Hi,
> >>
> >> I found a tricky problem in LXC, once I made a mistake in config, set
> >>
> >> lxc.cgroup.cpuset.cpus = -1
> >>
> >> ofcourse start would fail, but then "lxc-ls --active" showed the container
> >> is active.
> >>
> >> error message is:
> >> # lxc-start -n hq111 -f config_hq -l TRACE
> >> lxc-start: Invalid argument - write /cgroup/lxc/hq111/cpuset.cpus :
> >> Invalid argument
> >> lxc-start: Error setting cpuset.cpus to -1 for lxc/hq111
> >>
> >> lxc-start: failed to setup the cgroups for 'hq111'
> >> lxc-start: failed to spawn 'hq111'
> >> lxc-start: Device or resource busy - failed to remove cgroup
> >> '/cgroup/lxc/hq111'
> >>
> >>
> >> This is not hard to reproduce, just keep trying, not stable though.
> >> Then I read through the code and figured recursive_rmdir() failed, rmdir()
> >> return
> >> -1 sometimes, any idea how to fix this?
> >
> > Could you tell us exactly which version this is, and exactly how you
> > created the container? When I do it in ubuntu saucy (roughly 0.9.0 lxc),
> > the cgroup gets correctly removed.
> >
>
> Hi Serge,
>
> I think I have found the reason, when setup_cgroup() fail, the child process
> may still exist when the father try to destroy cgroup.(We have no sync
> mechanism
> to ensure child can exit before father when something wrong happen)
>
> commit 6031a6e5f939bda07d98768d34dafae677a7dfeb
> Author: Dwight Engen <dwight.en...@oracle.com>
> Date: Wed May 15 12:27:34 2013 -0400
>
> set non device cgroup items before the cgroup is entered
>
> This allows some special cgroup items such as memory.kmem.limit_in_bytes
> to be successfully set, since they must be set before any task is put
> into the cgroup.
>
> The devices cgroup is setup later giving the container a chance to mount
> file systems before the device it might want to mount from becomes
> unavailable.
>
> Signed-off-by: Dwight Engen <dwight.en...@oracle.com>
> Signed-off-by: Serge Hallyn <serge.hal...@ubuntu.com>
>
> This patch moved setup_cgroup() before lxc_cgroup_enter(), when setup_cgroup()
> fail, there is no task in cgroup, so remove cgroup wouldn't fail.
>
> So my problem no longer exists on the latest code, but there are still
> potential problems if we don't ensure child exit before father, such as
> Michael's problem, might also caused by this.
Right, so other failures later on *could* still cause this.
Shall we do something like
{
// Wait on any unterminated children
int status, ret;
while ((ret = waitpid(-1, &status, 0)) > 0);
}
in lxc_abort() after the kill(handler->pid)?
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