path: root/kernel/sched/fair.c
diff options
authorPhil Auld <pauld@redhat.com>2020-05-12 09:52:22 -0400
committerPeter Zijlstra <peterz@infradead.org>2020-05-19 20:34:10 +0200
commitb34cb07dde7c2346dec73d053ce926aeaa087303 (patch)
tree3719e46ad1755f7720fb8fab9bdf19c4fceb553d /kernel/sched/fair.c
parentb9bbe6ed63b2b9f2c9ee5cbd0f2c946a2723f4ce (diff)
sched/fair: Fix enqueue_task_fair() warning some more
sched/fair: Fix enqueue_task_fair warning some more The recent patch, fe61468b2cb (sched/fair: Fix enqueue_task_fair warning) did not fully resolve the issues with the rq->tmp_alone_branch != &rq->leaf_cfs_rq_list warning in enqueue_task_fair. There is a case where the first for_each_sched_entity loop exits due to on_rq, having incompletely updated the list. In this case the second for_each_sched_entity loop can further modify se. The later code to fix up the list management fails to do what is needed because se does not point to the sched_entity which broke out of the first loop. The list is not fixed up because the throttled parent was already added back to the list by a task enqueue in a parallel child hierarchy. Address this by calling list_add_leaf_cfs_rq if there are throttled parents while doing the second for_each_sched_entity loop. Fixes: fe61468b2cb ("sched/fair: Fix enqueue_task_fair warning") Suggested-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Phil Auld <pauld@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org> Link: https://lkml.kernel.org/r/20200512135222.GC2201@lorien.usersys.redhat.com
Diffstat (limited to 'kernel/sched/fair.c')
1 files changed, 7 insertions, 0 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 02f323b85b6d..c6d57c334d51 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5479,6 +5479,13 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
/* end evaluation on encountering a throttled cfs_rq */
if (cfs_rq_throttled(cfs_rq))
goto enqueue_throttle;
+ /*
+ * One parent has been throttled and cfs_rq removed from the
+ * list. Add it back to not break the leaf list.
+ */
+ if (throttled_hierarchy(cfs_rq))
+ list_add_leaf_cfs_rq(cfs_rq);