Mailinglist Archive: opensuse-factory (508 mails)

[Jeff Mahoney <jeffm@xxxxxxxx>]

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On 12/25/2010 08:45 AM, Mike Galbraith wrote:
> On Sat, 2010-12-25 at 12:15 +0100, Stefan Seyfried wrote:
>
> > And in plain english this means:
> >
> > "it is fixed in kernel-*-2.6.xxx.yyy-zzz.rpm" for which xxx, yyy and zzz?
> >
> > Or for which rpm changelog entry do we need to look? ;)
>
> The fix was baked on Christmas eve.. Christmas day is reserved for
> swilling eggnog and whatnot, so you'll have to wait a bit for it to
> appear in any tree :)

I've accepted this into the master kernel. It fixes the crashes and I'll
take the performance impact over a kernel oops until the real fix is
released.

Upstream discussion here:
http://groups.google.com/group/linux.kernel/browse_thread/thread/549060f23106acac/920f6adacc785e4f?lnk=gst&q=Zijlstra#920f6adacc785e4f

- -Jeff

> Subject: sched, cgroup: Use exit hook to avoid use-after-free crash
> From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Date: Fri, 24 Dec 2010 16:59:13 +0100
> References: <AANLkTin49UHeVhfS-iFwWvPIg29HPhXaP3DorBAa-a0I@xxxxxxxxxxxxxx>
>
> By not notifying the controller of the on-exit move back to
> init_css_set, we fail to move the task out of the previous cgroup's
> cfs_rq. This leads to an opportunity for a cgroup-destroy to come in and
> free the cgroup (there are no active tasks left in it after all) to
> which the not-quite dead task is still enqueued.
>
> Cc: stable@xxxxxxxxxx
> Reported-by: Miklos Vajna <vmiklos@xxxxxxxxxxxxxx>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> ---
>  kernel/sched.c |   10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> Index: linux-2.6.37.git/kernel/sched.c
> ===================================================================
> --- linux-2.6.37.git.orig/kernel/sched.c
> +++ linux-2.6.37.git/kernel/sched.c
> @@ -613,6 +613,9 @@ static inline struct task_group *task_gr
>       struct task_group *tg;
>       struct cgroup_subsys_state *css;
>  
> +     if (p->flags & PF_EXITING)
> +             return &root_task_group;
> +
>       css = task_subsys_state_check(p, cpu_cgroup_subsys_id,
>                       lockdep_is_held(&task_rq(p)->lock));
>       tg = container_of(css, struct task_group, css);
> @@ -9187,6 +9190,12 @@ cpu_cgroup_attach(struct cgroup_subsys *
>       }
>  }
>  
> +static void
> +cpu_cgroup_exit(struct cgroup_subsys *ss, struct task_struct *task)
> +{
> +     sched_move_task(task);
> +}
> +
>  #ifdef CONFIG_FAIR_GROUP_SCHED
>  static int cpu_shares_write_u64(struct cgroup *cgrp, struct cftype *cftype,
>                               u64 shareval)
> @@ -9259,6 +9268,7 @@ struct cgroup_subsys cpu_cgroup_subsys =
>       .destroy        = cpu_cgroup_destroy,
>       .can_attach     = cpu_cgroup_can_attach,
>       .attach         = cpu_cgroup_attach,
> +     .exit           = cpu_cgroup_exit,
>       .populate       = cpu_cgroup_populate,
>       .subsys_id      = cpu_cgroup_subsys_id,
>       .early_init     = 1,


- -- 
Jeff Mahoney
SUSE Labs
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