From 64be6f1f5f710f5995d41caf8a1767fe6d2b5a87 Mon Sep 17 00:00:00 2001 From: Juri Lelli Date: Fri, 24 Oct 2014 10:16:37 +0100 Subject: [PATCH] sched/deadline: Don't replenish from a !SCHED_DEADLINE entity In the deboost path, right after the dl_boosted flag has been reset, we can currently end up replenishing using -deadline parameters of a !SCHED_DEADLINE entity. This of course causes a bug, as those parameters are empty. In the case depicted above it is safe to simply bail out, as the deboosted task is going to be back to its original scheduling class anyway. Reported-by: Daniel Wagner Tested-by: Daniel Wagner Signed-off-by: Juri Lelli Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: vincent@legout.info Cc: Dario Faggioli Cc: Michael Trimarchi Cc: Fabio Checconi Link: http://lkml.kernel.org/r/1414142198-18552-4-git-send-email-juri.lelli@arm.com Signed-off-by: Ingo Molnar --- kernel/sched/deadline.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 256e577faf1b..92279eaf0ef2 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -847,8 +847,19 @@ static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags) * smaller than our one... OTW we keep our runtime and * deadline. */ - if (pi_task && p->dl.dl_boosted && dl_prio(pi_task->normal_prio)) + if (pi_task && p->dl.dl_boosted && dl_prio(pi_task->normal_prio)) { pi_se = &pi_task->dl; + } else if (!dl_prio(p->normal_prio)) { + /* + * Special case in which we have a !SCHED_DEADLINE task + * that is going to be deboosted, but exceedes its + * runtime while doing so. No point in replenishing + * it, as it's going to return back to its original + * scheduling class after this. + */ + BUG_ON(!p->dl.dl_boosted || flags != ENQUEUE_REPLENISH); + return; + } /* * If p is throttled, we do nothing. In fact, if it exhausted -- 2.20.1