sched: Fix load corruption from update_cfs_shares()
As part of enqueue_entity both a new entity weight and its contribution to the queuing cfs_rq / rq are updated. Since update_cfs_shares will only update the queueing weights when the entity is on_rq (which in this case it is not yet), there's a dependency loop here: update_cfs_shares needs account_entity_enqueue to update cfs_rq->load.weight account_entity_enqueue needs the updated weight for the queuing cfs_rq load[*] Fix this and avoid spurious dequeue/enqueues by issuing update_cfs_shares as if we had accounted the enqueue already. This was also resulting in rq->load corruption previously. [*]: this dependency also exists when using the group cfs_rq w/ update_cfs_shares as the weight of the enqueued entity changes without the load being updated. Signed-off-by: Paul Turner <pjt@google.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <20101115234937.844900206@google.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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@ -718,7 +718,7 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
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account_entity_enqueue(cfs_rq, se);
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}
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static void update_cfs_shares(struct cfs_rq *cfs_rq)
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static void update_cfs_shares(struct cfs_rq *cfs_rq, long weight_delta)
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{
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struct task_group *tg;
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struct sched_entity *se;
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@ -732,7 +732,7 @@ static void update_cfs_shares(struct cfs_rq *cfs_rq)
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if (!se)
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return;
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load = cfs_rq->load.weight;
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load = cfs_rq->load.weight + weight_delta;
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load_weight = atomic_read(&tg->load_weight);
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load_weight -= cfs_rq->load_contribution;
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@ -754,7 +754,7 @@ static inline void update_cfs_load(struct cfs_rq *cfs_rq, int lb)
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{
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}
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static inline void update_cfs_shares(struct cfs_rq *cfs_rq)
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static inline void update_cfs_shares(struct cfs_rq *cfs_rq, long weight_delta)
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{
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}
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#endif /* CONFIG_FAIR_GROUP_SCHED */
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@ -881,8 +881,8 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
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*/
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update_curr(cfs_rq);
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update_cfs_load(cfs_rq, 0);
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update_cfs_shares(cfs_rq, se->load.weight);
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account_entity_enqueue(cfs_rq, se);
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update_cfs_shares(cfs_rq);
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if (flags & ENQUEUE_WAKEUP) {
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place_entity(cfs_rq, se, 0);
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@ -944,7 +944,7 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
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update_cfs_load(cfs_rq, 0);
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account_entity_dequeue(cfs_rq, se);
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update_min_vruntime(cfs_rq);
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update_cfs_shares(cfs_rq);
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update_cfs_shares(cfs_rq, 0);
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/*
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* Normalize the entity after updating the min_vruntime because the
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@ -1177,7 +1177,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
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struct cfs_rq *cfs_rq = cfs_rq_of(se);
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update_cfs_load(cfs_rq, 0);
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update_cfs_shares(cfs_rq);
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update_cfs_shares(cfs_rq, 0);
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}
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hrtick_update(rq);
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@ -1207,7 +1207,7 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
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struct cfs_rq *cfs_rq = cfs_rq_of(se);
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update_cfs_load(cfs_rq, 0);
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update_cfs_shares(cfs_rq);
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update_cfs_shares(cfs_rq, 0);
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}
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hrtick_update(rq);
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@ -2034,7 +2034,7 @@ static int tg_shares_up(struct task_group *tg, int cpu)
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* We need to update shares after updating tg->load_weight in
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* order to adjust the weight of groups with long running tasks.
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*/
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update_cfs_shares(cfs_rq);
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update_cfs_shares(cfs_rq, 0);
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raw_spin_unlock_irqrestore(&rq->lock, flags);
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