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authorBrendan Jackman <brendan.jackman@arm.com>2017-10-05 12:45:16 +0100
committerIngo Molnar <mingo@kernel.org>2017-10-10 11:45:36 +0200
commit93f50f90247e3e926bbe9830df089c64a5cec236 (patch)
treea7b31f40fa439b4ee9b43c208d38fcc7f73bba0d /kernel/sched/fair.c
parent6fee85ccbc76e8aeba43dc120c5fa3c5409a4e2c (diff)
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sched/fair: Fix usage of find_idlest_group() when the local group is idlest
find_idlest_group() returns NULL when the local group is idlest. The caller then continues the find_idlest_group() search at a lower level of the current CPU's sched_domain hierarchy. find_idlest_group_cpu() is not consulted and, crucially, @new_cpu is not updated. This means the search is pointless and we return @prev_cpu from select_task_rq_fair(). This is fixed by initialising @new_cpu to @cpu instead of @prev_cpu. Signed-off-by: Brendan Jackman <brendan.jackman@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Josef Bacik <jbacik@fb.com> Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Josef Bacik <josef@toxicpanda.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Morten Rasmussen <morten.rasmussen@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20171005114516.18617-6-brendan.jackman@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched/fair.c')
-rw-r--r--kernel/sched/fair.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index ed80d6bd76c8..56f343b8e749 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5917,7 +5917,7 @@ find_idlest_group_cpu(struct sched_group *group, struct task_struct *p, int this
static inline int find_idlest_cpu(struct sched_domain *sd, struct task_struct *p,
int cpu, int prev_cpu, int sd_flag)
{
- int new_cpu = prev_cpu;
+ int new_cpu = cpu;
if (!cpumask_intersects(sched_domain_span(sd), &p->cpus_allowed))
return prev_cpu;