Re: [PATCH] sched: fix infinity loop in update_blocked_averages

[Vincent Guittot]

On Sun, 30 Dec 2018 at 13:04, Ingo Molnar <mingo@xxxxxxxxxx> wrote:
>
>
> * Vincent Guittot <vincent.guittot@xxxxxxxxxx> wrote:
>
> > > Reported-by: Zhipeng Xie <xiezhipeng1@xxxxxxxxxx>
> > > Cc: Bin Li <huawei.libin@xxxxxxxxxx>
> > > Cc: <stable@xxxxxxxxxxxxxxx>        [4.10+]
> > > Fixes: 9c2791f936ef (sched/fair: Fix hierarchical order in rq->leaf_cfs_rq_list)
> >
> > If it only happens in update_blocked_averages(), the del leaf has been added by:
> > a9e7f6544b9c (sched/fair: Fix O(nr_cgroups) in load balance path)
>
> So I think until we are confident in the proposed fixes, how about
> applying Linus's patch that reverts a9e7f6544b9c and simplifies the list
> manipulation?

looks good to me

Thanks
Vincent
>
> That way we can re-introduce the O(nr_cgroups) optimization without
> pressure.
>
> I'll prepare a commit for sched/urgent that does this, please holler if
> any of you disagrees!
>
> Thanks,
>
>         Ingo