On Thu, Jan 17, 2019 at 09:47:37AM +0100, Juri Lelli wrote:
> @@ -3233,11 +3233,11 @@ void cpuset_cpus_allowed(struct task_struct *tsk,
> struct cpumask *pmask)
> {
> unsigned long flags;
>
> - spin_lock_irqsave(&callback_lock, flags);
> + raw_spin_lock_irqsave(&callback_lock, flags);
> rcu_read_lock();
> guarantee_online_cpus(task_cs(tsk), pmask);
> rcu_read_unlock();
> - spin_unlock_irqrestore(&callback_lock, flags);
> + raw_spin_unlock_irqrestore(&callback_lock, flags);
> }
>
> void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
> @@ -3285,11 +3285,11 @@ nodemask_t cpuset_mems_allowed(struct task_struct
> *tsk)
> nodemask_t mask;
> unsigned long flags;
>
> - spin_lock_irqsave(&callback_lock, flags);
> + raw_spin_lock_irqsave(&callback_lock, flags);
> rcu_read_lock();
> guarantee_online_mems(task_cs(tsk), &mask);
> rcu_read_unlock();
> - spin_unlock_irqrestore(&callback_lock, flags);
> + raw_spin_unlock_irqrestore(&callback_lock, flags);
>
> return mask;
> }
> @@ -3381,14 +3381,14 @@ bool __cpuset_node_allowed(int node, gfp_t gfp_mask)
> return true;
>
> /* Not hardwall and node outside mems_allowed: scan up cpusets */
> - spin_lock_irqsave(&callback_lock, flags);
> + raw_spin_lock_irqsave(&callback_lock, flags);
>
> rcu_read_lock();
> cs = nearest_hardwall_ancestor(task_cs(current));
> allowed = node_isset(node, cs->mems_allowed);
> rcu_read_unlock();
>
> - spin_unlock_irqrestore(&callback_lock, flags);
> + raw_spin_unlock_irqrestore(&callback_lock, flags);
> return allowed;
> }
These three appear to be a user-controlled O(n) (depth of cgroup tree).
Which is basically bad for raw_spinlock_t.
The Changelog should really have mentioned this; and ideally we'd
somehow avoid this.
