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commit e3ed513bcf0097c0b8a1f1b4d791a8d0d8933b3b
parent 2a1a2c1a76cf89aaeb98a89179c2942c7882f68a
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Mon, 31 Dec 2018 09:54:17 -0800

Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler fix from Ingo Molnar:
 "This is a revert for a lockup in cgroups-intense workloads - the real
  fixes will come later"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/fair: Fix infinite loop in update_blocked_averages() by reverting a9e7f6544b9c

Diffstat:
Mkernel/sched/fair.c | 43+++++++++----------------------------------
1 file changed, 9 insertions(+), 34 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c @@ -352,10 +352,9 @@ static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq) } } -/* Iterate thr' all leaf cfs_rq's on a runqueue */ -#define for_each_leaf_cfs_rq_safe(rq, cfs_rq, pos) \ - list_for_each_entry_safe(cfs_rq, pos, &rq->leaf_cfs_rq_list, \ - leaf_cfs_rq_list) +/* Iterate through all leaf cfs_rq's on a runqueue: */ +#define for_each_leaf_cfs_rq(rq, cfs_rq) \ + list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list) /* Do the two (enqueued) entities belong to the same group ? */ static inline struct cfs_rq * @@ -447,8 +446,8 @@ static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq) { } -#define for_each_leaf_cfs_rq_safe(rq, cfs_rq, pos) \ - for (cfs_rq = &rq->cfs, pos = NULL; cfs_rq; cfs_rq = pos) +#define for_each_leaf_cfs_rq(rq, cfs_rq) \ + for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL) static inline struct sched_entity *parent_entity(struct sched_entity *se) { @@ -7647,27 +7646,10 @@ static inline bool others_have_blocked(struct rq *rq) #ifdef CONFIG_FAIR_GROUP_SCHED -static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq) -{ - if (cfs_rq->load.weight) - return false; - - if (cfs_rq->avg.load_sum) - return false; - - if (cfs_rq->avg.util_sum) - return false; - - if (cfs_rq->avg.runnable_load_sum) - return false; - - return true; -} - static void update_blocked_averages(int cpu) { struct rq *rq = cpu_rq(cpu); - struct cfs_rq *cfs_rq, *pos; + struct cfs_rq *cfs_rq; const struct sched_class *curr_class; struct rq_flags rf; bool done = true; @@ -7679,7 +7661,7 @@ static void update_blocked_averages(int cpu) * Iterates the task_group tree in a bottom up fashion, see * list_add_leaf_cfs_rq() for details. */ - for_each_leaf_cfs_rq_safe(rq, cfs_rq, pos) { + for_each_leaf_cfs_rq(rq, cfs_rq) { struct sched_entity *se; /* throttled entities do not contribute to load */ @@ -7694,13 +7676,6 @@ static void update_blocked_averages(int cpu) if (se && !skip_blocked_update(se)) update_load_avg(cfs_rq_of(se), se, 0); - /* - * 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)) - list_del_leaf_cfs_rq(cfs_rq); - /* Don't need periodic decay once load/util_avg are null */ if (cfs_rq_has_blocked(cfs_rq)) done = false; @@ -10570,10 +10545,10 @@ const struct sched_class fair_sched_class = { #ifdef CONFIG_SCHED_DEBUG void print_cfs_stats(struct seq_file *m, int cpu) { - struct cfs_rq *cfs_rq, *pos; + struct cfs_rq *cfs_rq; rcu_read_lock(); - for_each_leaf_cfs_rq_safe(cpu_rq(cpu), cfs_rq, pos) + for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq) print_cfs_rq(m, cpu, cfs_rq); rcu_read_unlock(); }