Hotplug operations are destructive w.r.t. cpusets. In case such an
operation is performed on a CPU belonging to an exlusive cpuset, the
-dl bandwidth information associated with the corresponding root
domain is gone even if the operation fails (in sched_cpu_inactive()).
For this reason we need to move the check we currently have in
sched_cpu_inactive() to cpuset_cpu_inactive() to prevent useless
cpusets reconfiguration in the CPU_DOWN_FAILED path.
Signed-off-by: Juri Lelli <juri.le...@arm.com>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Juri Lelli <juri.le...@gmail.com>
Cc: linux-kernel@vger.kernel.org
---
kernel/sched/core.c | 56 ++++++++++++++++++++++++++---------------------------
1 file changed, 28 insertions(+), 28 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 62671f5..213d26d 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5320,36 +5320,13 @@ static int sched_cpu_active(struct notifier_block *nfb,
static int sched_cpu_inactive(struct notifier_block *nfb,
unsigned long action, void *hcpu)
{
- unsigned long flags;
- long cpu = (long)hcpu;
- struct dl_bw *dl_b;
-
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_DOWN_PREPARE:
- set_cpu_active(cpu, false);
-
- /* explicitly allow suspend */
- if (!(action & CPU_TASKS_FROZEN)) {
- bool overflow;
- int cpus;
-
- rcu_read_lock_sched();
- dl_b = dl_bw_of(cpu);
-
- raw_spin_lock_irqsave(&dl_b->lock, flags);
- cpus = dl_bw_cpus(cpu);
- overflow = __dl_overflow(dl_b, cpus, 0, 0);
- raw_spin_unlock_irqrestore(&dl_b->lock, flags);
-
- rcu_read_unlock_sched();
-
- if (overflow)
- return notifier_from_errno(-EBUSY);
- }
+ set_cpu_active((long)hcpu, false);
return NOTIFY_OK;
+ default:
+ return NOTIFY_DONE;
}
-
- return NOTIFY_DONE;
}
static int __init migration_init(void)
@@ -7000,7 +6977,6 @@ static int cpuset_cpu_active(struct notifier_block *nfb,
unsigned long action,
*/
case CPU_ONLINE:
- case CPU_DOWN_FAILED:
cpuset_update_active_cpus(true);
break;
default:
@@ -7012,8 +6988,32 @@ static int cpuset_cpu_active(struct notifier_block *nfb,
unsigned long action,
static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long
action,
void *hcpu)
{
- switch (action) {
+ unsigned long flags;
+ long cpu = (long)hcpu;
+ struct dl_bw *dl_b;
+
+ switch (action & ~CPU_TASKS_FROZEN) {
case CPU_DOWN_PREPARE:
+ /* explicitly allow suspend */
+ if (!(action & CPU_TASKS_FROZEN)) {
+ bool overflow;
+ int cpus;
+
+ rcu_read_lock_sched();
+ dl_b = dl_bw_of(cpu);
+
+ raw_spin_lock_irqsave(&dl_b->lock, flags);
+ cpus = dl_bw_cpus(cpu);
+ overflow = __dl_overflow(dl_b, cpus, 0, 0);
+ raw_spin_unlock_irqrestore(&dl_b->lock, flags);
+
+ rcu_read_unlock_sched();
+
+ if (overflow) {
+ trace_printk("hotplug failed for cpu %lu", cpu);
+ return notifier_from_errno(-EBUSY);
+ }
+ }
cpuset_update_active_cpus(false);
break;
case CPU_DOWN_PREPARE_FROZEN:
--
2.2.2
--
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