Nathan Lynch wrote:
> Paul Jackson wrote:
> >
> > If there is some decent way I can get the cpus_allowed of the top
> > cpuset to track the cpu_online_map, then we avoid this discontinuity
> > in system behaviour.
>
>
> How about this? I've verified it fixes the issue but I'm nervous
> about the locking.
>
>
> --- cpuhp-sched_setaffinity.orig/kernel/cpuset.c
> +++ cpuhp-sched_setaffinity/kernel/cpuset.c
> @@ -2033,6 +2033,31 @@ out:
> return err;
> }
>
> +static int cpuset_handle_cpuhp(struct notifier_block *nb,
> + unsigned long phase, void *_cpu)
> +{
> + unsigned long cpu = (unsigned long)_cpu;
> +
> + mutex_lock(&manage_mutex);
> + lock_cpu_hotplug();
> + mutex_lock(&callback_mutex);
> +
> + switch (phase) {
> + case CPU_ONLINE:
> + cpu_set(cpu, top_cpuset.cpus_allowed);
> + break;
> + case CPU_DEAD:
> + cpu_clear(cpu, top_cpuset.cpus_allowed);
> + break;
> + }
> +
> + mutex_unlock(&callback_mutex);
> + unlock_cpu_hotplug();
> + mutex_unlock(&manage_mutex);
> +
> + return 0;
> +}
Actually the lock/unlock_cpu_hotplug aren't necessary,
cpu_add_remove_lock is already held in this context.
Update cpus_allowed in top_cpuset when cpus are hotplugged;
otherwise binding a task to a newly hotplugged cpu fails since the
toplevel cpuset has a static copy of whatever cpu_online_map was at
boot time.
Signed-off-by: Nathan Lynch <[email protected]>
--- cpuhp-sched_setaffinity.orig/kernel/cpuset.c
+++ cpuhp-sched_setaffinity/kernel/cpuset.c
@@ -2033,6 +2033,29 @@ out:
return err;
}
+static int cpuset_handle_cpuhp(struct notifier_block *nb,
+ unsigned long phase, void *_cpu)
+{
+ unsigned long cpu = (unsigned long)_cpu;
+
+ mutex_lock(&manage_mutex);
+ mutex_lock(&callback_mutex);
+
+ switch (phase) {
+ case CPU_ONLINE:
+ cpu_set(cpu, top_cpuset.cpus_allowed);
+ break;
+ case CPU_DEAD:
+ cpu_clear(cpu, top_cpuset.cpus_allowed);
+ break;
+ }
+
+ mutex_unlock(&callback_mutex);
+ mutex_unlock(&manage_mutex);
+
+ return 0;
+}
+
/**
* cpuset_init_smp - initialize cpus_allowed
*
@@ -2043,6 +2066,8 @@ void __init cpuset_init_smp(void)
{
top_cpuset.cpus_allowed = cpu_online_map;
top_cpuset.mems_allowed = node_online_map;
+
+ hotcpu_notifier(cpuset_handle_cpuhp, 0);
}
/**
-
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