On Mon, 8 Mar 2010, Miao Xie wrote:
> Changes from V1 to V2:
> - cleanup two unnecessary smp_wmb() at cpuset_migrate_mm()
>
This patch is already in -mm without this update, so it's probably better
to make this an incremental series basedo n mmotm-2010-03-04-18-05 or
later.
> @@ -2090,15 +2086,19 @@ static int cpuset_track_online_cpus(struct notifier_block *unused_nb,
> static int cpuset_track_online_nodes(struct notifier_block *self,
> unsigned long action, void *arg)
> {
> + nodemask_t oldmems;
> +
> cgroup_lock();
> switch (action) {
> case MEM_ONLINE:
> - case MEM_OFFLINE:
> + oldmems = top_cpuset.mems_allowed;
> mutex_lock(&callback_mutex);
> top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
> mutex_unlock(&callback_mutex);
> - if (action == MEM_OFFLINE)
> - scan_for_empty_cpusets(&top_cpuset);
> + update_tasks_nodemask(&top_cpuset, &oldmems, NULL);
> + break;
> + case MEM_OFFLINE:
> + scan_for_empty_cpusets(&top_cpuset);
> break;
> default:
> break;
This looks wrong, why isn't top_cpuset.mems_allowed updated for
MEM_OFFLINE? If you're going to update it when a new node comes online
for (struct memory_notify *)arg->status_change_nid is >= 0, then it should
be removed from the nodemask when offlined as well. You'd be calling
scan_for_empty_cpusets() needlessly in this code since it'll never change
under your hotplug code.
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