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

From: Ingo Molnar
Date: Sun Dec 30 2018 - 07:04:49 EST

* 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

That way we can re-introduce the O(nr_cgroups) optimization without

I'll prepare a commit for sched/urgent that does this, please holler if
any of you disagrees!