lkml.org 
[lkml]   [2018]   [Dec]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH] sched: fix infinity loop in update_blocked_averages
Date
Hi Tejun,

On Fri, Dec 28, 2018 10:03 AM, Tejun Heo wrote:
>
> On Thu, Dec 27, 2018 at 05:53:52PM -0800, Tejun Heo wrote:
> > Vincent knows that part way better than me but I think the safest way
> > would be doing the optimization removal iff tmp_alone_branch is
> > already pointing to leaf_cfs_rq_list. IIUC, it's pointing to
> > something else only while a branch is being built and deferring
> > optimization removal by an avg update cycle isn't gonna make any
> > difference anyway.
>
> So, something like the following. Xie, can you see whether the
> following patch resolves the problem?
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index d1907506318a..88b9118b5191 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -7698,7 +7698,8 @@ static void update_blocked_averages(int cpu)
> * There can be a lot of idle CPU cgroups. Don't let fully
> * decayed cfs_rqs linger on the list.
> */
> - if (cfs_rq_is_decayed(cfs_rq))
> + if (cfs_rq_is_decayed(cfs_rq) &&
> + rq->tmp_alone_branch == &rq->leaf_cfs_rq_list)
> list_del_leaf_cfs_rq(cfs_rq);
>
> /* Don't need periodic decay once load/util_avg are null */
Tested-by: Zhipeng Xie <xiezhipeng1@huawei.com>

This patch fixes things for me, we haven't seen a crash yet.

--
Thanks,
Zhipeng Xie

\
 
 \ /
  Last update: 2018-12-28 11:25    [W:0.134 / U:2.884 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site