Commit a1ba4d8b authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

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: default avatarThomas Gleixner <tglx@linutronix.de>
CC: stable@kernel.org
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: default avatarGregory Haskins <ghaskins@novell.com>
LKML-Reference: <1247067476.9777.57.camel@twins>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent d4ec36ba

kernel/sched.c

+1 −0
Original line number Diff line number Diff line
@@ -493,6 +493,7 @@ struct rt_rq { 
#endif

#ifdef CONFIG_SMP

	unsigned long rt_nr_migratory;

	unsigned long rt_nr_total;

	int overloaded;

	struct plist_head pushable_tasks;

#endif

kernel/sched_rt.c

+17 −1
Original line number Diff line number Diff line
@@ -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--;

CRA Git | Maintained and supported by SUSTech CRA and CCSE