Hi Li Zefan and Tejun Heo, It would be great if you could please have a look at the proposed change below (and the rest of the set of course :-). Another bit that I'd be more comfortable after hearing your word on it is this one (discussed over 5/5): https://lore.kernel.org/lkml/20180925130750.GA25664@localhost.localdomain/ Best, - Juri On 03/09/18 16:27, Juri Lelli wrote: > callback_lock grants the holder read-only access to cpusets. For fixing > a synchronization issue between cpusets and scheduler core, it is now > required to make callback_lock available to core scheduler code. > > Convert callback_lock to raw_spin_lock, so that it will be always safe > to acquire it from atomic context. > > Signed-off-by: Juri Lelli <juri.lelli@xxxxxxxxxx> > --- > kernel/cgroup/cpuset.c | 66 +++++++++++++++++++++--------------------- > 1 file changed, 33 insertions(+), 33 deletions(-) > > diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c > index 266f10cb7222..5b43f482fa0f 100644 > --- a/kernel/cgroup/cpuset.c > +++ b/kernel/cgroup/cpuset.c > @@ -288,7 +288,7 @@ static struct cpuset top_cpuset = { > */ > > static DEFINE_MUTEX(cpuset_mutex); > -static DEFINE_SPINLOCK(callback_lock); > +static DEFINE_RAW_SPINLOCK(callback_lock); > > static struct workqueue_struct *cpuset_migrate_mm_wq; > > @@ -922,9 +922,9 @@ static void update_cpumasks_hier(struct cpuset *cs, struct cpumask *new_cpus) > continue; > rcu_read_unlock(); > > - spin_lock_irq(&callback_lock); > + raw_spin_lock_irq(&callback_lock); > cpumask_copy(cp->effective_cpus, new_cpus); > - spin_unlock_irq(&callback_lock); > + raw_spin_unlock_irq(&callback_lock); > > WARN_ON(!is_in_v2_mode() && > !cpumask_equal(cp->cpus_allowed, cp->effective_cpus)); > @@ -989,9 +989,9 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs, > if (retval < 0) > return retval; > > - spin_lock_irq(&callback_lock); > + raw_spin_lock_irq(&callback_lock); > cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed); > - spin_unlock_irq(&callback_lock); > + raw_spin_unlock_irq(&callback_lock); > > /* use trialcs->cpus_allowed as a temp variable */ > update_cpumasks_hier(cs, trialcs->cpus_allowed); > @@ -1175,9 +1175,9 @@ static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems) > continue; > rcu_read_unlock(); > > - spin_lock_irq(&callback_lock); > + raw_spin_lock_irq(&callback_lock); > cp->effective_mems = *new_mems; > - spin_unlock_irq(&callback_lock); > + raw_spin_unlock_irq(&callback_lock); > > WARN_ON(!is_in_v2_mode() && > !nodes_equal(cp->mems_allowed, cp->effective_mems)); > @@ -1245,9 +1245,9 @@ static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs, > if (retval < 0) > goto done; > > - spin_lock_irq(&callback_lock); > + raw_spin_lock_irq(&callback_lock); > cs->mems_allowed = trialcs->mems_allowed; > - spin_unlock_irq(&callback_lock); > + raw_spin_unlock_irq(&callback_lock); > > /* use trialcs->mems_allowed as a temp variable */ > update_nodemasks_hier(cs, &trialcs->mems_allowed); > @@ -1338,9 +1338,9 @@ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, > spread_flag_changed = ((is_spread_slab(cs) != is_spread_slab(trialcs)) > || (is_spread_page(cs) != is_spread_page(trialcs))); > > - spin_lock_irq(&callback_lock); > + raw_spin_lock_irq(&callback_lock); > cs->flags = trialcs->flags; > - spin_unlock_irq(&callback_lock); > + raw_spin_unlock_irq(&callback_lock); > > if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed) > rebuild_sched_domains_locked(); > @@ -1755,7 +1755,7 @@ static int cpuset_common_seq_show(struct seq_file *sf, void *v) > cpuset_filetype_t type = seq_cft(sf)->private; > int ret = 0; > > - spin_lock_irq(&callback_lock); > + raw_spin_lock_irq(&callback_lock); > > switch (type) { > case FILE_CPULIST: > @@ -1774,7 +1774,7 @@ static int cpuset_common_seq_show(struct seq_file *sf, void *v) > ret = -EINVAL; > } > > - spin_unlock_irq(&callback_lock); > + raw_spin_unlock_irq(&callback_lock); > return ret; > } > > @@ -1989,12 +1989,12 @@ static int cpuset_css_online(struct cgroup_subsys_state *css) > > cpuset_inc(); > > - spin_lock_irq(&callback_lock); > + raw_spin_lock_irq(&callback_lock); > if (is_in_v2_mode()) { > cpumask_copy(cs->effective_cpus, parent->effective_cpus); > cs->effective_mems = parent->effective_mems; > } > - spin_unlock_irq(&callback_lock); > + raw_spin_unlock_irq(&callback_lock); > > if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags)) > goto out_unlock; > @@ -2021,12 +2021,12 @@ static int cpuset_css_online(struct cgroup_subsys_state *css) > } > rcu_read_unlock(); > > - spin_lock_irq(&callback_lock); > + raw_spin_lock_irq(&callback_lock); > cs->mems_allowed = parent->mems_allowed; > cs->effective_mems = parent->mems_allowed; > cpumask_copy(cs->cpus_allowed, parent->cpus_allowed); > cpumask_copy(cs->effective_cpus, parent->cpus_allowed); > - spin_unlock_irq(&callback_lock); > + raw_spin_unlock_irq(&callback_lock); > out_unlock: > mutex_unlock(&cpuset_mutex); > return 0; > @@ -2065,7 +2065,7 @@ static void cpuset_css_free(struct cgroup_subsys_state *css) > static void cpuset_bind(struct cgroup_subsys_state *root_css) > { > mutex_lock(&cpuset_mutex); > - spin_lock_irq(&callback_lock); > + raw_spin_lock_irq(&callback_lock); > > if (is_in_v2_mode()) { > cpumask_copy(top_cpuset.cpus_allowed, cpu_possible_mask); > @@ -2076,7 +2076,7 @@ static void cpuset_bind(struct cgroup_subsys_state *root_css) > top_cpuset.mems_allowed = top_cpuset.effective_mems; > } > > - spin_unlock_irq(&callback_lock); > + raw_spin_unlock_irq(&callback_lock); > mutex_unlock(&cpuset_mutex); > } > > @@ -2174,12 +2174,12 @@ hotplug_update_tasks_legacy(struct cpuset *cs, > { > bool is_empty; > > - spin_lock_irq(&callback_lock); > + raw_spin_lock_irq(&callback_lock); > cpumask_copy(cs->cpus_allowed, new_cpus); > cpumask_copy(cs->effective_cpus, new_cpus); > cs->mems_allowed = *new_mems; > cs->effective_mems = *new_mems; > - spin_unlock_irq(&callback_lock); > + raw_spin_unlock_irq(&callback_lock); > > /* > * Don't call update_tasks_cpumask() if the cpuset becomes empty, > @@ -2216,10 +2216,10 @@ hotplug_update_tasks(struct cpuset *cs, > if (nodes_empty(*new_mems)) > *new_mems = parent_cs(cs)->effective_mems; > > - spin_lock_irq(&callback_lock); > + raw_spin_lock_irq(&callback_lock); > cpumask_copy(cs->effective_cpus, new_cpus); > cs->effective_mems = *new_mems; > - spin_unlock_irq(&callback_lock); > + raw_spin_unlock_irq(&callback_lock); > > if (cpus_updated) > update_tasks_cpumask(cs); > @@ -2312,21 +2312,21 @@ static void cpuset_hotplug_workfn(struct work_struct *work) > > /* synchronize cpus_allowed to cpu_active_mask */ > if (cpus_updated) { > - spin_lock_irq(&callback_lock); > + raw_spin_lock_irq(&callback_lock); > if (!on_dfl) > cpumask_copy(top_cpuset.cpus_allowed, &new_cpus); > cpumask_copy(top_cpuset.effective_cpus, &new_cpus); > - spin_unlock_irq(&callback_lock); > + raw_spin_unlock_irq(&callback_lock); > /* we don't mess with cpumasks of tasks in top_cpuset */ > } > > /* synchronize mems_allowed to N_MEMORY */ > if (mems_updated) { > - spin_lock_irq(&callback_lock); > + raw_spin_lock_irq(&callback_lock); > if (!on_dfl) > top_cpuset.mems_allowed = new_mems; > top_cpuset.effective_mems = new_mems; > - spin_unlock_irq(&callback_lock); > + raw_spin_unlock_irq(&callback_lock); > update_tasks_nodemask(&top_cpuset); > } > > @@ -2425,11 +2425,11 @@ 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) > @@ -2477,11 +2477,11 @@ 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; > } > @@ -2573,14 +2573,14 @@ 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; > } > > -- > 2.17.1 >
