Re: [BUG][PANIC] cgroup panics with mmotm for 2.6.28-rc7

From: Balbir Singh
Date: Mon Dec 15 2008 - 22:53:17 EST


* Li Zefan <lizf@xxxxxxxxxxxxxx> [2008-12-16 10:53:48]:

> Li Zefan wrote:
> > Paul Menage wrote:
> >> That implies that we ran out of css_set objects when moving the task
> >> into the new cgroup.
> >>
> >> Did you have all of the configured controllers mounted, or just a subset?
> >>
> >> What date was this mmotm? Was it after Li's patch fixes went in on 8th Dec?
> >>
> >
> > It is probably my fault. :( I'm looking into this problem.
> >
> > There are 2 related cleanup patches in -mm:
> >
> > cgroups-add-inactive-subsystems-to-rootnodesubsys_list.patch (and -fix.patch)
> > cgroups-introduce-link_css_set-to-remove-duplicate-code.patch (and -fix.patch)
> >
> > If the bug is reproducable, could you revert the above patches and seee if the
> > bug is still there.
> >
> >> Paul
> >>
> >> On Mon, Dec 15, 2008 at 3:32 AM, Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx> wrote:
> >>> Hi, Paul,
> >>>
> >>> I see the following stack trace when I run my tests. I've not yet
> >>> investigated the problem.
> >>>
> >>> ------------[ cut here ]------------
> >>> kernel BUG at kernel/cgroup.c:392!
>
> In latest -mm, this BUG_ON is line 398, and before the below 2 fixlet patches,
> the BUG_ON is line 392, so I guess you were using older -mm:
>
> cgroups-add-inactive-subsystems-to-rootnodesubsys_list-fix.patch
> cgroups-introduce-link_css_set-to-remove-duplicate-code-fix.patch
>
> Could you try the latest -mm kernel, or apply
> cgroups-add-inactive-subsystems-to-rootnodesubsys_list-fix.patch ?
>
> diff -puN kernel/cgroup.c~cgroups-add-inactive-subsystems-to-rootnodesubsys_list-fix kernel/cgroup.c
> --- a/kernel/cgroup.c~cgroups-add-inactive-subsystems-to-rootnodesubsys_list-fix
> +++ a/kernel/cgroup.c
> @@ -2521,7 +2521,7 @@ static void __init cgroup_init_subsys(st
> printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name);
>
> /* Create the top cgroup state for this subsystem */
> - list_add(&ss->sibling, &rootnode.root_list);
> + list_add(&ss->sibling, &rootnode.subsys_list);
> ss->root = &rootnode;
> css = ss->create(ss, dummytop);
> /* We don't handle early failures gracefully */
>

I'll move to the latest mm and make sure your fix is present.

--
Balbir
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