On Thu, 7 May 2020 at 22:36, Phil Auld <pa...@redhat.com> wrote: > > 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 no longer points to the sched_entity which broke > out of the first loop. > > Address this by calling leaf_add_rq_list 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.guit...@linaro.org> > Signed-off-by: Phil Auld <pa...@redhat.com> > Cc: Peter Zijlstra (Intel) <pet...@infradead.org> > Cc: Vincent Guittot <vincent.guit...@linaro.org> > Cc: Ingo Molnar <mi...@kernel.org> > Cc: Juri Lelli <juri.le...@redhat.com> With the Fixes tag and the typo mentioned by Tao Reviewed-by: Vincent Guittot <vincent.guit...@linaro.org> > --- > kernel/sched/fair.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > 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); > } > > enqueue_throttle: > -- > 2.18.0 > > V2 rework the fix based on Vincent's suggestion. Thanks Vincent. > > > Cheers, > Phil > > -- >
