From a1ba4d8ba9f06a397e97cbd67a93ee306860b40a Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Wed, 1 Apr 2009 18:40:15 +0200
Subject: sched_rt: Fix overload bug on rt group scheduling
Fixes an easily triggerable BUG() when setting process affinities.
Make sure to count the number of migratable tasks in the same place:
the root rt_rq. Otherwise the number doesn't make sense and we'll hit
the BUG in set_cpus_allowed_rt().
Also, make sure we only count tasks, not groups (this is probably
already taken care of by the fact that rt_se->nr_cpus_allowed will be 0
for groups, but be more explicit)
Tested-by: Thomas Gleixner <tglx@linutronix.de>
CC: stable@kernel.org
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Gregory Haskins <ghaskins@novell.com>
LKML-Reference: <1247067476.9777.57.camel@twins>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
kernel/sched_rt.c | 18 +++++++++++++++++-
1 file changed, 17 insertions(+), 1 deletion(-)
(limited to 'kernel/sched_rt.c')
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 9bf0d2a73045..3918e01994e0 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -10,6 +10,8 @@ static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
#ifdef CONFIG_RT_GROUP_SCHED
+#define rt_entity_is_task(rt_se) (!(rt_se)->my_q)
+
static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
{
return rt_rq->rq;
@@ -22,6 +24,8 @@ static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
#else /* CONFIG_RT_GROUP_SCHED */
+#define rt_entity_is_task(rt_se) (1)
+
static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
{
return container_of(rt_rq, struct rq, rt);
@@ -73,7 +77,7 @@ static inline void rt_clear_overload(struct rq *rq)
static void update_rt_migration(struct rt_rq *rt_rq)
{
- if (rt_rq->rt_nr_migratory && (rt_rq->rt_nr_running > 1)) {
+ if (rt_rq->rt_nr_migratory && rt_rq->rt_nr_total > 1) {
if (!rt_rq->overloaded) {
rt_set_overload(rq_of_rt_rq(rt_rq));
rt_rq->overloaded = 1;
@@ -86,6 +90,12 @@ static void update_rt_migration(struct rt_rq *rt_rq)
static void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
{
+ if (!rt_entity_is_task(rt_se))
+ return;
+
+ rt_rq = &rq_of_rt_rq(rt_rq)->rt;
+
+ rt_rq->rt_nr_total++;
if (rt_se->nr_cpus_allowed > 1)
rt_rq->rt_nr_migratory++;
@@ -94,6 +104,12 @@ static void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
static void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
{
+ if (!rt_entity_is_task(rt_se))
+ return;
+
+ rt_rq = &rq_of_rt_rq(rt_rq)->rt;
+
+ rt_rq->rt_nr_total--;
if (rt_se->nr_cpus_allowed > 1)
rt_rq->rt_nr_migratory--;
--
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