Messages in this thread Patch in this message | | | Date | Fri, 28 Feb 2020 16:32:03 +0000 | From | Qais Yousef <> | Subject | Re: 5.6-rc3: WARNING: CPU: 48 PID: 17435 at kernel/sched/fair.c:380 enqueue_task_fair+0x328/0x440 |
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On 02/28/20 16:42, Christian Borntraeger wrote: > > > On 28.02.20 16:37, Vincent Guittot wrote: > > On Fri, 28 Feb 2020 at 16:08, Christian Borntraeger > > <borntraeger@de.ibm.com> wrote: > >> > >> Also happened with 5.4: > >> Seems that I just happen to have an interesting test workload/system size interaction > >> on a newly installed system that triggers this. > > > > you will probably go back to 5.1 which is the version where we put > > back the deletion of unused cfs_rq from the list which can trigger the > > warning: > > commit 039ae8bcf7a5 : (Fix O(nr_cgroups) in the load balancing path) > > > > AFAICT, we haven't changed this since > > So you do know what is the problem? If not is there any debug option or > patch that I could apply to give you more information? >
It might be a long shot as I'm not particularly knowledgeable about this code path, but could we be missing rcu_read_lock/unlock around the call to unthrottle_cfs_rq() here?
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diff --git a/kernel/sched/core.c b/kernel/sched/core.c index fc1dfc007604..56aa5cfbb7f1 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7434,6 +7434,7 @@ static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota)
raw_spin_unlock_irq(&cfs_b->lock);
+ rcu_read_lock(); for_each_online_cpu(i) { struct cfs_rq *cfs_rq = tg->cfs_rq[i]; struct rq *rq = cfs_rq->rq; @@ -7447,6 +7448,7 @@ static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota) unthrottle_cfs_rq(cfs_rq); rq_unlock_irq(rq, &rf); } + rcu_read_unlock(); if (runtime_was_enabled && !runtime_enabled) cfs_bandwidth_usage_dec(); out_unlock:
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