Update Linux to v5.10.109
Sourced from [1]
[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.109.tar.xz
Change-Id: I19bca9fc6762d4e63bcf3e4cba88bbe560d9c76c
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index 9154e74..b7f38f3 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -179,6 +179,8 @@
static void psi_avgs_work(struct work_struct *work);
+static void poll_timer_fn(struct timer_list *t);
+
static void group_init(struct psi_group *group)
{
int cpu;
@@ -190,7 +192,6 @@
INIT_DELAYED_WORK(&group->avgs_work, psi_avgs_work);
mutex_init(&group->avgs_lock);
/* Init trigger-related members */
- atomic_set(&group->poll_scheduled, 0);
mutex_init(&group->trigger_lock);
INIT_LIST_HEAD(&group->triggers);
memset(group->nr_triggers, 0, sizeof(group->nr_triggers));
@@ -199,7 +200,9 @@
memset(group->polling_total, 0, sizeof(group->polling_total));
group->polling_next_update = ULLONG_MAX;
group->polling_until = 0;
- rcu_assign_pointer(group->poll_kworker, NULL);
+ init_waitqueue_head(&group->poll_wait);
+ timer_setup(&group->poll_timer, poll_timer_fn, 0);
+ rcu_assign_pointer(group->poll_task, NULL);
}
void __init psi_init(void)
@@ -225,7 +228,7 @@
case PSI_MEM_FULL:
return tasks[NR_MEMSTALL] && !tasks[NR_RUNNING];
case PSI_CPU_SOME:
- return tasks[NR_RUNNING] > 1;
+ return tasks[NR_RUNNING] > tasks[NR_ONCPU];
case PSI_NONIDLE:
return tasks[NR_IOWAIT] || tasks[NR_MEMSTALL] ||
tasks[NR_RUNNING];
@@ -547,47 +550,38 @@
return now + group->poll_min_period;
}
-/*
- * Schedule polling if it's not already scheduled. It's safe to call even from
- * hotpath because even though kthread_queue_delayed_work takes worker->lock
- * spinlock that spinlock is never contended due to poll_scheduled atomic
- * preventing such competition.
- */
+/* Schedule polling if it's not already scheduled. */
static void psi_schedule_poll_work(struct psi_group *group, unsigned long delay)
{
- struct kthread_worker *kworker;
+ struct task_struct *task;
- /* Do not reschedule if already scheduled */
- if (atomic_cmpxchg(&group->poll_scheduled, 0, 1) != 0)
+ /*
+ * Do not reschedule if already scheduled.
+ * Possible race with a timer scheduled after this check but before
+ * mod_timer below can be tolerated because group->polling_next_update
+ * will keep updates on schedule.
+ */
+ if (timer_pending(&group->poll_timer))
return;
rcu_read_lock();
- kworker = rcu_dereference(group->poll_kworker);
+ task = rcu_dereference(group->poll_task);
/*
* kworker might be NULL in case psi_trigger_destroy races with
* psi_task_change (hotpath) which can't use locks
*/
- if (likely(kworker))
- kthread_queue_delayed_work(kworker, &group->poll_work, delay);
- else
- atomic_set(&group->poll_scheduled, 0);
+ if (likely(task))
+ mod_timer(&group->poll_timer, jiffies + delay);
rcu_read_unlock();
}
-static void psi_poll_work(struct kthread_work *work)
+static void psi_poll_work(struct psi_group *group)
{
- struct kthread_delayed_work *dwork;
- struct psi_group *group;
u32 changed_states;
u64 now;
- dwork = container_of(work, struct kthread_delayed_work, work);
- group = container_of(dwork, struct psi_group, poll_work);
-
- atomic_set(&group->poll_scheduled, 0);
-
mutex_lock(&group->trigger_lock);
now = sched_clock();
@@ -623,6 +617,32 @@
mutex_unlock(&group->trigger_lock);
}
+static int psi_poll_worker(void *data)
+{
+ struct psi_group *group = (struct psi_group *)data;
+
+ sched_set_fifo_low(current);
+
+ while (true) {
+ wait_event_interruptible(group->poll_wait,
+ atomic_cmpxchg(&group->poll_wakeup, 1, 0) ||
+ kthread_should_stop());
+ if (kthread_should_stop())
+ break;
+
+ psi_poll_work(group);
+ }
+ return 0;
+}
+
+static void poll_timer_fn(struct timer_list *t)
+{
+ struct psi_group *group = from_timer(group, t, poll_timer);
+
+ atomic_set(&group->poll_wakeup, 1);
+ wake_up_interruptible(&group->poll_wait);
+}
+
static void record_times(struct psi_group_cpu *groupc, int cpu,
bool memstall_tick)
{
@@ -669,13 +689,14 @@
groupc->times[PSI_NONIDLE] += delta;
}
-static u32 psi_group_change(struct psi_group *group, int cpu,
- unsigned int clear, unsigned int set)
+static void psi_group_change(struct psi_group *group, int cpu,
+ unsigned int clear, unsigned int set,
+ bool wake_clock)
{
struct psi_group_cpu *groupc;
+ u32 state_mask = 0;
unsigned int t, m;
enum psi_states s;
- u32 state_mask = 0;
groupc = per_cpu_ptr(group->pcpu, cpu);
@@ -694,14 +715,15 @@
for (t = 0, m = clear; m; m &= ~(1 << t), t++) {
if (!(m & (1 << t)))
continue;
- if (groupc->tasks[t] == 0 && !psi_bug) {
- printk_deferred(KERN_ERR "psi: task underflow! cpu=%d t=%d tasks=[%u %u %u] clear=%x set=%x\n",
+ if (groupc->tasks[t]) {
+ groupc->tasks[t]--;
+ } else if (!psi_bug) {
+ printk_deferred(KERN_ERR "psi: task underflow! cpu=%d t=%d tasks=[%u %u %u %u] clear=%x set=%x\n",
cpu, t, groupc->tasks[0],
groupc->tasks[1], groupc->tasks[2],
- clear, set);
+ groupc->tasks[3], clear, set);
psi_bug = 1;
}
- groupc->tasks[t]--;
}
for (t = 0; set; set &= ~(1 << t), t++)
@@ -717,7 +739,11 @@
write_seqcount_end(&groupc->seq);
- return state_mask;
+ if (state_mask & group->poll_states)
+ psi_schedule_poll_work(group, 1);
+
+ if (wake_clock && !delayed_work_pending(&group->avgs_work))
+ schedule_delayed_work(&group->avgs_work, PSI_FREQ);
}
static struct psi_group *iterate_groups(struct task_struct *task, void **iter)
@@ -744,6 +770,21 @@
return &psi_system;
}
+static void psi_flags_change(struct task_struct *task, int clear, int set)
+{
+ if (((task->psi_flags & set) ||
+ (task->psi_flags & clear) != clear) &&
+ !psi_bug) {
+ printk_deferred(KERN_ERR "psi: inconsistent task state! task=%d:%s cpu=%d psi_flags=%x clear=%x set=%x\n",
+ task->pid, task->comm, task_cpu(task),
+ task->psi_flags, clear, set);
+ psi_bug = 1;
+ }
+
+ task->psi_flags &= ~clear;
+ task->psi_flags |= set;
+}
+
void psi_task_change(struct task_struct *task, int clear, int set)
{
int cpu = task_cpu(task);
@@ -754,17 +795,7 @@
if (!task->pid)
return;
- if (((task->psi_flags & set) ||
- (task->psi_flags & clear) != clear) &&
- !psi_bug) {
- printk_deferred(KERN_ERR "psi: inconsistent task state! task=%d:%s cpu=%d psi_flags=%x clear=%x set=%x\n",
- task->pid, task->comm, cpu,
- task->psi_flags, clear, set);
- psi_bug = 1;
- }
-
- task->psi_flags &= ~clear;
- task->psi_flags |= set;
+ psi_flags_change(task, clear, set);
/*
* Periodic aggregation shuts off if there is a period of no
@@ -777,14 +808,51 @@
wq_worker_last_func(task) == psi_avgs_work))
wake_clock = false;
- while ((group = iterate_groups(task, &iter))) {
- u32 state_mask = psi_group_change(group, cpu, clear, set);
+ while ((group = iterate_groups(task, &iter)))
+ psi_group_change(group, cpu, clear, set, wake_clock);
+}
- if (state_mask & group->poll_states)
- psi_schedule_poll_work(group, 1);
+void psi_task_switch(struct task_struct *prev, struct task_struct *next,
+ bool sleep)
+{
+ struct psi_group *group, *common = NULL;
+ int cpu = task_cpu(prev);
+ void *iter;
- if (wake_clock && !delayed_work_pending(&group->avgs_work))
- schedule_delayed_work(&group->avgs_work, PSI_FREQ);
+ if (next->pid) {
+ psi_flags_change(next, 0, TSK_ONCPU);
+ /*
+ * When moving state between tasks, the group that
+ * contains them both does not change: we can stop
+ * updating the tree once we reach the first common
+ * ancestor. Iterate @next's ancestors until we
+ * encounter @prev's state.
+ */
+ iter = NULL;
+ while ((group = iterate_groups(next, &iter))) {
+ if (per_cpu_ptr(group->pcpu, cpu)->tasks[NR_ONCPU]) {
+ common = group;
+ break;
+ }
+
+ psi_group_change(group, cpu, 0, TSK_ONCPU, true);
+ }
+ }
+
+ /*
+ * If this is a voluntary sleep, dequeue will have taken care
+ * of the outgoing TSK_ONCPU alongside TSK_RUNNING already. We
+ * only need to deal with it during preemption.
+ */
+ if (sleep)
+ return;
+
+ if (prev->pid) {
+ psi_flags_change(prev, TSK_ONCPU, 0);
+
+ iter = NULL;
+ while ((group = iterate_groups(prev, &iter)) && group != common)
+ psi_group_change(group, cpu, TSK_ONCPU, 0, true);
}
}
@@ -818,17 +886,17 @@
if (static_branch_likely(&psi_disabled))
return;
- *flags = current->flags & PF_MEMSTALL;
+ *flags = current->in_memstall;
if (*flags)
return;
/*
- * PF_MEMSTALL setting & accounting needs to be atomic wrt
+ * in_memstall setting & accounting needs to be atomic wrt
* changes to the task's scheduling state, otherwise we can
* race with CPU migration.
*/
rq = this_rq_lock_irq(&rf);
- current->flags |= PF_MEMSTALL;
+ current->in_memstall = 1;
psi_task_change(current, 0, TSK_MEMSTALL);
rq_unlock_irq(rq, &rf);
@@ -851,13 +919,13 @@
if (*flags)
return;
/*
- * PF_MEMSTALL clearing & accounting needs to be atomic wrt
+ * in_memstall clearing & accounting needs to be atomic wrt
* changes to the task's scheduling state, otherwise we could
* race with CPU migration.
*/
rq = this_rq_lock_irq(&rf);
- current->flags &= ~PF_MEMSTALL;
+ current->in_memstall = 0;
psi_task_change(current, TSK_MEMSTALL, 0);
rq_unlock_irq(rq, &rf);
@@ -916,12 +984,14 @@
rq = task_rq_lock(task, &rf);
- if (task_on_rq_queued(task))
+ if (task_on_rq_queued(task)) {
task_flags = TSK_RUNNING;
- else if (task->in_iowait)
+ if (task_current(rq, task))
+ task_flags |= TSK_ONCPU;
+ } else if (task->in_iowait)
task_flags = TSK_IOWAIT;
- if (task->flags & PF_MEMSTALL)
+ if (task->in_memstall)
task_flags |= TSK_MEMSTALL;
if (task_flags)
@@ -1046,26 +1116,21 @@
t->event = 0;
t->last_event_time = 0;
init_waitqueue_head(&t->event_wait);
- kref_init(&t->refcount);
mutex_lock(&group->trigger_lock);
- if (!rcu_access_pointer(group->poll_kworker)) {
- struct sched_param param = {
- .sched_priority = 1,
- };
- struct kthread_worker *kworker;
+ if (!rcu_access_pointer(group->poll_task)) {
+ struct task_struct *task;
- kworker = kthread_create_worker(0, "psimon");
- if (IS_ERR(kworker)) {
+ task = kthread_create(psi_poll_worker, group, "psimon");
+ if (IS_ERR(task)) {
kfree(t);
mutex_unlock(&group->trigger_lock);
- return ERR_CAST(kworker);
+ return ERR_CAST(task);
}
- sched_setscheduler_nocheck(kworker->task, SCHED_FIFO, ¶m);
- kthread_init_delayed_work(&group->poll_work,
- psi_poll_work);
- rcu_assign_pointer(group->poll_kworker, kworker);
+ atomic_set(&group->poll_wakeup, 0);
+ wake_up_process(task);
+ rcu_assign_pointer(group->poll_task, task);
}
list_add(&t->node, &group->triggers);
@@ -1079,15 +1144,19 @@
return t;
}
-static void psi_trigger_destroy(struct kref *ref)
+void psi_trigger_destroy(struct psi_trigger *t)
{
- struct psi_trigger *t = container_of(ref, struct psi_trigger, refcount);
- struct psi_group *group = t->group;
- struct kthread_worker *kworker_to_destroy = NULL;
+ struct psi_group *group;
+ struct task_struct *task_to_destroy = NULL;
- if (static_branch_likely(&psi_disabled))
+ /*
+ * We do not check psi_disabled since it might have been disabled after
+ * the trigger got created.
+ */
+ if (!t)
return;
+ group = t->group;
/*
* Wakeup waiters to stop polling. Can happen if cgroup is deleted
* from under a polling process.
@@ -1109,55 +1178,39 @@
period = min(period, div_u64(tmp->win.size,
UPDATES_PER_WINDOW));
group->poll_min_period = period;
- /* Destroy poll_kworker when the last trigger is destroyed */
+ /* Destroy poll_task when the last trigger is destroyed */
if (group->poll_states == 0) {
group->polling_until = 0;
- kworker_to_destroy = rcu_dereference_protected(
- group->poll_kworker,
+ task_to_destroy = rcu_dereference_protected(
+ group->poll_task,
lockdep_is_held(&group->trigger_lock));
- rcu_assign_pointer(group->poll_kworker, NULL);
+ rcu_assign_pointer(group->poll_task, NULL);
+ del_timer(&group->poll_timer);
}
}
mutex_unlock(&group->trigger_lock);
/*
- * Wait for both *trigger_ptr from psi_trigger_replace and
- * poll_kworker RCUs to complete their read-side critical sections
- * before destroying the trigger and optionally the poll_kworker
+ * Wait for psi_schedule_poll_work RCU to complete its read-side
+ * critical section before destroying the trigger and optionally the
+ * poll_task.
*/
synchronize_rcu();
/*
- * Destroy the kworker after releasing trigger_lock to prevent a
+ * Stop kthread 'psimon' after releasing trigger_lock to prevent a
* deadlock while waiting for psi_poll_work to acquire trigger_lock
*/
- if (kworker_to_destroy) {
+ if (task_to_destroy) {
/*
* After the RCU grace period has expired, the worker
- * can no longer be found through group->poll_kworker.
- * But it might have been already scheduled before
- * that - deschedule it cleanly before destroying it.
+ * can no longer be found through group->poll_task.
*/
- kthread_cancel_delayed_work_sync(&group->poll_work);
- atomic_set(&group->poll_scheduled, 0);
-
- kthread_destroy_worker(kworker_to_destroy);
+ kthread_stop(task_to_destroy);
}
kfree(t);
}
-void psi_trigger_replace(void **trigger_ptr, struct psi_trigger *new)
-{
- struct psi_trigger *old = *trigger_ptr;
-
- if (static_branch_likely(&psi_disabled))
- return;
-
- rcu_assign_pointer(*trigger_ptr, new);
- if (old)
- kref_put(&old->refcount, psi_trigger_destroy);
-}
-
__poll_t psi_trigger_poll(void **trigger_ptr,
struct file *file, poll_table *wait)
{
@@ -1167,24 +1220,15 @@
if (static_branch_likely(&psi_disabled))
return DEFAULT_POLLMASK | EPOLLERR | EPOLLPRI;
- rcu_read_lock();
-
- t = rcu_dereference(*(void __rcu __force **)trigger_ptr);
- if (!t) {
- rcu_read_unlock();
+ t = smp_load_acquire(trigger_ptr);
+ if (!t)
return DEFAULT_POLLMASK | EPOLLERR | EPOLLPRI;
- }
- kref_get(&t->refcount);
-
- rcu_read_unlock();
poll_wait(file, &t->event_wait, wait);
if (cmpxchg(&t->event, 1, 0) == 1)
ret |= EPOLLPRI;
- kref_put(&t->refcount, psi_trigger_destroy);
-
return ret;
}
@@ -1208,14 +1252,24 @@
buf[buf_size - 1] = '\0';
- new = psi_trigger_create(&psi_system, buf, nbytes, res);
- if (IS_ERR(new))
- return PTR_ERR(new);
-
seq = file->private_data;
+
/* Take seq->lock to protect seq->private from concurrent writes */
mutex_lock(&seq->lock);
- psi_trigger_replace(&seq->private, new);
+
+ /* Allow only one trigger per file descriptor */
+ if (seq->private) {
+ mutex_unlock(&seq->lock);
+ return -EBUSY;
+ }
+
+ new = psi_trigger_create(&psi_system, buf, nbytes, res);
+ if (IS_ERR(new)) {
+ mutex_unlock(&seq->lock);
+ return PTR_ERR(new);
+ }
+
+ smp_store_release(&seq->private, new);
mutex_unlock(&seq->lock);
return nbytes;
@@ -1250,43 +1304,45 @@
{
struct seq_file *seq = file->private_data;
- psi_trigger_replace(&seq->private, NULL);
+ psi_trigger_destroy(seq->private);
return single_release(inode, file);
}
-static const struct file_operations psi_io_fops = {
- .open = psi_io_open,
- .read = seq_read,
- .llseek = seq_lseek,
- .write = psi_io_write,
- .poll = psi_fop_poll,
- .release = psi_fop_release,
+static const struct proc_ops psi_io_proc_ops = {
+ .proc_open = psi_io_open,
+ .proc_read = seq_read,
+ .proc_lseek = seq_lseek,
+ .proc_write = psi_io_write,
+ .proc_poll = psi_fop_poll,
+ .proc_release = psi_fop_release,
};
-static const struct file_operations psi_memory_fops = {
- .open = psi_memory_open,
- .read = seq_read,
- .llseek = seq_lseek,
- .write = psi_memory_write,
- .poll = psi_fop_poll,
- .release = psi_fop_release,
+static const struct proc_ops psi_memory_proc_ops = {
+ .proc_open = psi_memory_open,
+ .proc_read = seq_read,
+ .proc_lseek = seq_lseek,
+ .proc_write = psi_memory_write,
+ .proc_poll = psi_fop_poll,
+ .proc_release = psi_fop_release,
};
-static const struct file_operations psi_cpu_fops = {
- .open = psi_cpu_open,
- .read = seq_read,
- .llseek = seq_lseek,
- .write = psi_cpu_write,
- .poll = psi_fop_poll,
- .release = psi_fop_release,
+static const struct proc_ops psi_cpu_proc_ops = {
+ .proc_open = psi_cpu_open,
+ .proc_read = seq_read,
+ .proc_lseek = seq_lseek,
+ .proc_write = psi_cpu_write,
+ .proc_poll = psi_fop_poll,
+ .proc_release = psi_fop_release,
};
static int __init psi_proc_init(void)
{
- proc_mkdir("pressure", NULL);
- proc_create("pressure/io", 0, NULL, &psi_io_fops);
- proc_create("pressure/memory", 0, NULL, &psi_memory_fops);
- proc_create("pressure/cpu", 0, NULL, &psi_cpu_fops);
+ if (psi_enable) {
+ proc_mkdir("pressure", NULL);
+ proc_create("pressure/io", 0, NULL, &psi_io_proc_ops);
+ proc_create("pressure/memory", 0, NULL, &psi_memory_proc_ops);
+ proc_create("pressure/cpu", 0, NULL, &psi_cpu_proc_ops);
+ }
return 0;
}
module_init(psi_proc_init);