From 60e69eed85bb7b5198ef70643b5895c26ad76ef7 Mon Sep 17 00:00:00 2001
From: Mike Galbraith <bitbucket@online.de>
Date: Mon, 7 Apr 2014 10:55:15 +0200
Subject: sched/numa: Fix task_numa_free() lockdep splat

Sasha reported that lockdep claims that the following commit:
made numa_group.lock interrupt unsafe:

  156654f491dd ("sched/numa: Move task_numa_free() to __put_task_struct()")

While I don't see how that could be, given the commit in question moved
task_numa_free() from one irq enabled region to another, the below does
make both gripes and lockups upon gripe with numa=fake=4 go away.

Reported-by: Sasha Levin <sasha.levin@oracle.com>
Fixes: 156654f491dd ("sched/numa: Move task_numa_free() to __put_task_struct()")
Signed-off-by: Mike Galbraith <bitbucket@online.de>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: torvalds@linux-foundation.org
Cc: mgorman@suse.com
Cc: akpm@linux-foundation.org
Cc: Dave Jones <davej@redhat.com>
Link: http://lkml.kernel.org/r/1396860915.5170.5.camel@marge.simpson.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/sched/fair.c  | 13 +++++++------
 kernel/sched/sched.h |  9 +++++++++
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 7e9bd0b1fa9e..4f14a656a720 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1497,7 +1497,7 @@ static void task_numa_placement(struct task_struct *p)
 	/* If the task is part of a group prevent parallel updates to group stats */
 	if (p->numa_group) {
 		group_lock = &p->numa_group->lock;
-		spin_lock(group_lock);
+		spin_lock_irq(group_lock);
 	}
 
 	/* Find the node with the highest number of faults */
@@ -1572,7 +1572,7 @@ static void task_numa_placement(struct task_struct *p)
 			}
 		}
 
-		spin_unlock(group_lock);
+		spin_unlock_irq(group_lock);
 	}
 
 	/* Preferred node as the node with the most faults */
@@ -1677,7 +1677,8 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags,
 	if (!join)
 		return;
 
-	double_lock(&my_grp->lock, &grp->lock);
+	BUG_ON(irqs_disabled());
+	double_lock_irq(&my_grp->lock, &grp->lock);
 
 	for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) {
 		my_grp->faults[i] -= p->numa_faults_memory[i];
@@ -1691,7 +1692,7 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags,
 	grp->nr_tasks++;
 
 	spin_unlock(&my_grp->lock);
-	spin_unlock(&grp->lock);
+	spin_unlock_irq(&grp->lock);
 
 	rcu_assign_pointer(p->numa_group, grp);
 
@@ -1710,14 +1711,14 @@ void task_numa_free(struct task_struct *p)
 	void *numa_faults = p->numa_faults_memory;
 
 	if (grp) {
-		spin_lock(&grp->lock);
+		spin_lock_irq(&grp->lock);
 		for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++)
 			grp->faults[i] -= p->numa_faults_memory[i];
 		grp->total_faults -= p->total_numa_faults;
 
 		list_del(&p->numa_entry);
 		grp->nr_tasks--;
-		spin_unlock(&grp->lock);
+		spin_unlock_irq(&grp->lock);
 		rcu_assign_pointer(p->numa_group, NULL);
 		put_numa_group(grp);
 	}
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index c9007f28d3a2..456e492a3dca 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1385,6 +1385,15 @@ static inline void double_lock(spinlock_t *l1, spinlock_t *l2)
 	spin_lock_nested(l2, SINGLE_DEPTH_NESTING);
 }
 
+static inline void double_lock_irq(spinlock_t *l1, spinlock_t *l2)
+{
+	if (l1 > l2)
+		swap(l1, l2);
+
+	spin_lock_irq(l1);
+	spin_lock_nested(l2, SINGLE_DEPTH_NESTING);
+}
+
 static inline void double_raw_lock(raw_spinlock_t *l1, raw_spinlock_t *l2)
 {
 	if (l1 > l2)
-- 
cgit v1.2.3


From a1d9a3231eac4117cadaf4b6bba5b2902c15a33e Mon Sep 17 00:00:00 2001
From: Kirill Tkhai <tkhai@yandex.ru>
Date: Thu, 10 Apr 2014 17:38:36 +0400
Subject: sched: Check for stop task appearance when balancing happens

We need to do it like we do for the other higher priority classes..

Signed-off-by: Kirill Tkhai <tkhai@yandex.ru>
Cc: Michael wang <wangyun@linux.vnet.ibm.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/336561397137116@web27h.yandex.ru
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/sched/deadline.c | 11 ++++++++++-
 kernel/sched/fair.c     |  3 ++-
 kernel/sched/rt.c       |  7 ++++---
 3 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 27ef40925525..b08095786cb8 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1021,8 +1021,17 @@ struct task_struct *pick_next_task_dl(struct rq *rq, struct task_struct *prev)
 
 	dl_rq = &rq->dl;
 
-	if (need_pull_dl_task(rq, prev))
+	if (need_pull_dl_task(rq, prev)) {
 		pull_dl_task(rq);
+		/*
+		 * pull_rt_task() can drop (and re-acquire) rq->lock; this
+		 * means a stop task can slip in, in which case we need to
+		 * re-start task selection.
+		 */
+		if (rq->stop && rq->stop->on_rq)
+			return RETRY_TASK;
+	}
+
 	/*
 	 * When prev is DL, we may throttle it in put_prev_task().
 	 * So, we update time before we check for dl_nr_running.
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 4f14a656a720..7570dd969c28 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6728,7 +6728,8 @@ static int idle_balance(struct rq *this_rq)
 out:
 	/* Is there a task of a high priority class? */
 	if (this_rq->nr_running != this_rq->cfs.h_nr_running &&
-	    (this_rq->dl.dl_nr_running ||
+	    ((this_rq->stop && this_rq->stop->on_rq) ||
+	     this_rq->dl.dl_nr_running ||
 	     (this_rq->rt.rt_nr_running && !rt_rq_throttled(&this_rq->rt))))
 		pulled_task = -1;
 
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index d8cdf1618551..bd2267ad404f 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1362,10 +1362,11 @@ pick_next_task_rt(struct rq *rq, struct task_struct *prev)
 		pull_rt_task(rq);
 		/*
 		 * pull_rt_task() can drop (and re-acquire) rq->lock; this
-		 * means a dl task can slip in, in which case we need to
-		 * re-start task selection.
+		 * means a dl or stop task can slip in, in which case we need
+		 * to re-start task selection.
 		 */
-		if (unlikely(rq->dl.dl_nr_running))
+		if (unlikely((rq->stop && rq->stop->on_rq) ||
+			     rq->dl.dl_nr_running))
 			return RETRY_TASK;
 	}
 
-- 
cgit v1.2.3