linux-kernel - [GIT pull] scheduler fixes for 4.20

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Date:   Sun, 11 Nov 2018 09:11:08 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...nel.org>
Subject: [GIT pull] scheduler fixes for 4.20

Linus,

please pull the latest sched-urgent-for-linus git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched-urgent-for-linus

Two small scheduler fixes:

  - Take hotplug lock in sched_init_smp(). Technically not really required,
    but lockdep will complain other.

  - Trivial comment fix in sched/fair


Thanks,

	tglx

------------------>
Valentin Schneider (1):
      sched/core: Take the hotplug lock in sched_init_smp()

Yi Wang (1):
      sched/fair: Fix a comment in task_numa_fault()


 kernel/sched/core.c | 5 ++++-
 kernel/sched/fair.c | 4 ++--
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index fd2fce8a001b..02a20ef196a6 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5859,11 +5859,14 @@ void __init sched_init_smp(void)
 	/*
 	 * There's no userspace yet to cause hotplug operations; hence all the
 	 * CPU masks are stable and all blatant races in the below code cannot
-	 * happen.
+	 * happen. The hotplug lock is nevertheless taken to satisfy lockdep,
+	 * but there won't be any contention on it.
 	 */
+	cpus_read_lock();
 	mutex_lock(&sched_domains_mutex);
 	sched_init_domains(cpu_active_mask);
 	mutex_unlock(&sched_domains_mutex);
+	cpus_read_unlock();
 
 	/* Move init over to a non-isolated CPU */
 	if (set_cpus_allowed_ptr(current, housekeeping_cpumask(HK_FLAG_DOMAIN)) < 0)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index ee271bb661cc..3648d0300fdf 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2400,8 +2400,8 @@ void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags)
 		local = 1;
 
 	/*
-	 * Retry task to preferred node migration periodically, in case it
-	 * case it previously failed, or the scheduler moved us.
+	 * Retry to migrate task to preferred node periodically, in case it
+	 * previously failed, or the scheduler moved us.
 	 */
 	if (time_after(jiffies, p->numa_migrate_retry)) {
 		task_numa_placement(p);