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Subject: [PATCH -tip 05/32] sched/fair: Add a few assertions
Date:   Tue, 17 Nov 2020 18:19:35 -0500
Message-Id: <20201117232003.3580179-6-joel@joelfernandes.org>
In-Reply-To: <20201117232003.3580179-1-joel@joelfernandes.org>
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From: Peter Zijlstra <peterz@infradead.org>

Tested-by: Julien Desfossez <jdesfossez@digitalocean.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
---
 kernel/sched/fair.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 51483a00a755..ca35bfc0a368 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6245,6 +6245,11 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target)
 		task_util = uclamp_task_util(p);
 	}
 
+	/*
+	 * per-cpu select_idle_mask usage
+	 */
+	lockdep_assert_irqs_disabled();
+
 	if ((available_idle_cpu(target) || sched_idle_cpu(target)) &&
 	    asym_fits_capacity(task_util, target))
 		return target;
@@ -6710,8 +6715,6 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu)
  * certain conditions an idle sibling CPU if the domain has SD_WAKE_AFFINE set.
  *
  * Returns the target CPU number.
- *
- * preempt must be disabled.
  */
 static int
 select_task_rq_fair(struct task_struct *p, int prev_cpu, int wake_flags)
@@ -6724,6 +6727,10 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int wake_flags)
 	/* SD_flags and WF_flags share the first nibble */
 	int sd_flag = wake_flags & 0xF;
 
+	/*
+	 * required for stable ->cpus_allowed
+	 */
+	lockdep_assert_held(&p->pi_lock);
 	if (wake_flags & WF_TTWU) {
 		record_wakee(p);
 
-- 
2.29.2.299.gdc1121823c-goog