4.14-stable review patch. If anyone has any objections, please let me know.
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From: Luca Abeni luca.abeni@santannapisa.it
commit 295d6d5e373607729bcc8182c25afe964655714f upstream.
Fix a bug introduced in:
72f9f3fdc928 ("sched/deadline: Remove dl_new from struct sched_dl_entity")
After that commit, when switching to -deadline if the scheduling deadline of a task is in the past then switched_to_dl() calls setup_new_entity() to properly initialize the scheduling deadline and runtime.
The problem is that the task is enqueued _before_ having its parameters initialized by setup_new_entity(), and this can cause problems. For example, a task with its out-of-date deadline in the past will potentially be enqueued as the highest priority one; however, its adjusted deadline may not be the earliest one.
This patch fixes the problem by initializing the task's parameters before enqueuing it.
Signed-off-by: luca abeni luca.abeni@santannapisa.it Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Reviewed-by: Daniel Bristot de Oliveira bristot@redhat.com Cc: Juri Lelli juri.lelli@arm.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Mathieu Poirier mathieu.poirier@linaro.org Cc: Mike Galbraith efault@gmx.de Cc: Peter Zijlstra peterz@infradead.org Cc: Steven Rostedt rostedt@goodmis.org Cc: Thomas Gleixner tglx@linutronix.de Link: http://lkml.kernel.org/r/1504778971-13573-3-git-send-email-luca.abeni@santan... Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Sudip Mukherjee sudipm.mukherjee@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- kernel/sched/deadline.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-)
--- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1365,6 +1365,10 @@ enqueue_dl_entity(struct sched_dl_entity update_dl_entity(dl_se, pi_se); } else if (flags & ENQUEUE_REPLENISH) { replenish_dl_entity(dl_se, pi_se); + } else if ((flags & ENQUEUE_RESTORE) && + dl_time_before(dl_se->deadline, + rq_clock(rq_of_dl_rq(dl_rq_of_se(dl_se))))) { + setup_new_dl_entity(dl_se); }
__enqueue_dl_entity(dl_se); @@ -2256,13 +2260,6 @@ static void switched_to_dl(struct rq *rq
return; } - /* - * If p is boosted we already updated its params in - * rt_mutex_setprio()->enqueue_task(..., ENQUEUE_REPLENISH), - * p's deadline being now already after rq_clock(rq). - */ - if (dl_time_before(p->dl.deadline, rq_clock(rq))) - setup_new_dl_entity(&p->dl);
if (rq->curr != p) { #ifdef CONFIG_SMP