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authorPeter Zijlstra <peterz@infradead.org>2020-07-08 11:38:59 +0200
committerPeter Zijlstra <peterz@infradead.org>2020-07-08 11:38:59 +0200
commitfaa2fd7cbad4609d06d7904c0a80cf2f8cd23678 (patch)
tree3a5bfcc8879b719aec97cb73ed6e020cde502546 /kernel/sched
parent01e377c539ca52a6c753d0fdbe93b3b8fcd66a1c (diff)
parentce3614daabea8a2d01c1dd17ae41d1ec5e5ae7db (diff)
Merge branch 'sched/urgent'
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/core.c113
-rw-r--r--kernel/sched/deadline.c1
-rw-r--r--kernel/sched/fair.c2
-rw-r--r--kernel/sched/idle.c15
-rw-r--r--kernel/sched/sched.h2
5 files changed, 101 insertions, 32 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 0a08d0c235d4..15c980af63db 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1313,9 +1313,6 @@ static inline void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
void activate_task(struct rq *rq, struct task_struct *p, int flags)
{
- if (task_contributes_to_load(p))
- rq->nr_uninterruptible--;
-
enqueue_task(rq, p, flags);
p->on_rq = TASK_ON_RQ_QUEUED;
@@ -1325,9 +1322,6 @@ void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
{
p->on_rq = (flags & DEQUEUE_SLEEP) ? 0 : TASK_ON_RQ_MIGRATING;
- if (task_contributes_to_load(p))
- rq->nr_uninterruptible++;
-
dequeue_task(rq, p, flags);
}
@@ -1629,7 +1623,7 @@ static int __set_cpus_allowed_ptr(struct task_struct *p,
goto out;
}
- if (cpumask_equal(p->cpus_ptr, new_mask))
+ if (cpumask_equal(&p->cpus_mask, new_mask))
goto out;
/*
@@ -2228,10 +2222,10 @@ ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags,
lockdep_assert_held(&rq->lock);
-#ifdef CONFIG_SMP
if (p->sched_contributes_to_load)
rq->nr_uninterruptible--;
+#ifdef CONFIG_SMP
if (wake_flags & WF_MIGRATED)
en_flags |= ENQUEUE_MIGRATED;
#endif
@@ -2285,8 +2279,15 @@ void sched_ttwu_pending(void *arg)
rq_lock_irqsave(rq, &rf);
update_rq_clock(rq);
- llist_for_each_entry_safe(p, t, llist, wake_entry)
+ llist_for_each_entry_safe(p, t, llist, wake_entry.llist) {
+ if (WARN_ON_ONCE(p->on_cpu))
+ smp_cond_load_acquire(&p->on_cpu, !VAL);
+
+ if (WARN_ON_ONCE(task_cpu(p) != cpu_of(rq)))
+ set_task_cpu(p, cpu_of(rq));
+
ttwu_do_activate(rq, p, p->sched_remote_wakeup ? WF_MIGRATED : 0, &rf);
+ }
rq_unlock_irqrestore(rq, &rf);
}
@@ -2314,7 +2315,7 @@ static void __ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags
p->sched_remote_wakeup = !!(wake_flags & WF_MIGRATED);
WRITE_ONCE(rq->ttwu_pending, 1);
- __smp_call_single_queue(cpu, &p->wake_entry);
+ __smp_call_single_queue(cpu, &p->wake_entry.llist);
}
void wake_up_if_idle(int cpu)
@@ -2361,7 +2362,7 @@ static inline bool ttwu_queue_cond(int cpu, int wake_flags)
* the soon-to-be-idle CPU as the current CPU is likely busy.
* nr_running is checked to avoid unnecessary task stacking.
*/
- if ((wake_flags & WF_ON_RQ) && cpu_rq(cpu)->nr_running <= 1)
+ if ((wake_flags & WF_ON_CPU) && cpu_rq(cpu)->nr_running <= 1)
return true;
return false;
@@ -2370,6 +2371,9 @@ static inline bool ttwu_queue_cond(int cpu, int wake_flags)
static bool ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags)
{
if (sched_feat(TTWU_QUEUE) && ttwu_queue_cond(cpu, wake_flags)) {
+ if (WARN_ON_ONCE(cpu == smp_processor_id()))
+ return false;
+
sched_clock_cpu(cpu); /* Sync clocks across CPUs */
__ttwu_queue_wakelist(p, cpu, wake_flags);
return true;
@@ -2520,7 +2524,6 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
goto out;
success = 1;
- cpu = task_cpu(p);
trace_sched_waking(p);
p->state = TASK_RUNNING;
trace_sched_wakeup(p);
@@ -2542,7 +2545,6 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
/* We're going to change ->state: */
success = 1;
- cpu = task_cpu(p);
/*
* Ensure we load p->on_rq _after_ p->state, otherwise it would
@@ -2567,7 +2569,7 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
* A similar smb_rmb() lives in try_invoke_on_locked_down_task().
*/
smp_rmb();
- if (p->on_rq && ttwu_remote(p, wake_flags))
+ if (READ_ONCE(p->on_rq) && ttwu_remote(p, wake_flags))
goto unlock;
if (p->in_iowait) {
@@ -2576,9 +2578,6 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
}
#ifdef CONFIG_SMP
- p->sched_contributes_to_load = !!task_contributes_to_load(p);
- p->state = TASK_WAKING;
-
/*
* Ensure we load p->on_cpu _after_ p->on_rq, otherwise it would be
* possible to, falsely, observe p->on_cpu == 0.
@@ -2597,8 +2596,20 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
*
* Pairs with the LOCK+smp_mb__after_spinlock() on rq->lock in
* __schedule(). See the comment for smp_mb__after_spinlock().
+ *
+ * Form a control-dep-acquire with p->on_rq == 0 above, to ensure
+ * schedule()'s deactivate_task() has 'happened' and p will no longer
+ * care about it's own p->state. See the comment in __schedule().
*/
- smp_rmb();
+ smp_acquire__after_ctrl_dep();
+
+ /*
+ * We're doing the wakeup (@success == 1), they did a dequeue (p->on_rq
+ * == 0), which means we need to do an enqueue, change p->state to
+ * TASK_WAKING such that we can unlock p->pi_lock before doing the
+ * enqueue, such as ttwu_queue_wakelist().
+ */
+ p->state = TASK_WAKING;
/*
* If the owning (remote) CPU is still in the middle of schedule() with
@@ -2606,8 +2617,21 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
* which potentially sends an IPI instead of spinning on p->on_cpu to
* let the waker make forward progress. This is safe because IRQs are
* disabled and the IPI will deliver after on_cpu is cleared.
+ *
+ * Ensure we load task_cpu(p) after p->on_cpu:
+ *
+ * set_task_cpu(p, cpu);
+ * STORE p->cpu = @cpu
+ * __schedule() (switch to task 'p')
+ * LOCK rq->lock
+ * smp_mb__after_spin_lock() smp_cond_load_acquire(&p->on_cpu)
+ * STORE p->on_cpu = 1 LOAD p->cpu
+ *
+ * to ensure we observe the correct CPU on which the task is currently
+ * scheduling.
*/
- if (READ_ONCE(p->on_cpu) && ttwu_queue_wakelist(p, cpu, wake_flags | WF_ON_RQ))
+ if (smp_load_acquire(&p->on_cpu) &&
+ ttwu_queue_wakelist(p, task_cpu(p), wake_flags | WF_ON_CPU))
goto unlock;
/*
@@ -2627,6 +2651,8 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
psi_ttwu_dequeue(p);
set_task_cpu(p, cpu);
}
+#else
+ cpu = task_cpu(p);
#endif /* CONFIG_SMP */
ttwu_queue(p, cpu, wake_flags);
@@ -2634,7 +2660,7 @@ unlock:
raw_spin_unlock_irqrestore(&p->pi_lock, flags);
out:
if (success)
- ttwu_stat(p, cpu, wake_flags);
+ ttwu_stat(p, task_cpu(p), wake_flags);
preempt_enable();
return success;
@@ -2755,7 +2781,7 @@ static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
#endif
init_numa_balancing(clone_flags, p);
#ifdef CONFIG_SMP
- p->wake_entry_type = CSD_TYPE_TTWU;
+ p->wake_entry.u_flags = CSD_TYPE_TTWU;
#endif
}
@@ -2931,6 +2957,7 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p)
* Silence PROVE_RCU.
*/
raw_spin_lock_irqsave(&p->pi_lock, flags);
+ rseq_migrate(p);
/*
* We're setting the CPU for the first time, we don't migrate,
* so use __set_task_cpu().
@@ -2995,6 +3022,7 @@ void wake_up_new_task(struct task_struct *p)
* as we're not fully set-up yet.
*/
p->recent_used_cpu = task_cpu(p);
+ rseq_migrate(p);
__set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0));
#endif
rq = __task_rq_lock(p, &rf);
@@ -4065,6 +4093,7 @@ static void __sched notrace __schedule(bool preempt)
{
struct task_struct *prev, *next;
unsigned long *switch_count;
+ unsigned long prev_state;
struct rq_flags rf;
struct rq *rq;
int cpu;
@@ -4081,12 +4110,22 @@ static void __sched notrace __schedule(bool preempt)
local_irq_disable();
rcu_note_context_switch(preempt);
+ /* See deactivate_task() below. */
+ prev_state = prev->state;
+
/*
* Make sure that signal_pending_state()->signal_pending() below
* can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
- * done by the caller to avoid the race with signal_wake_up().
+ * done by the caller to avoid the race with signal_wake_up():
+ *
+ * __set_current_state(@state) signal_wake_up()
+ * schedule() set_tsk_thread_flag(p, TIF_SIGPENDING)
+ * wake_up_state(p, state)
+ * LOCK rq->lock LOCK p->pi_state
+ * smp_mb__after_spinlock() smp_mb__after_spinlock()
+ * if (signal_pending_state()) if (p->state & @state)
*
- * The membarrier system call requires a full memory barrier
+ * Also, the membarrier system call requires a full memory barrier
* after coming from user-space, before storing to rq->curr.
*/
rq_lock(rq, &rf);
@@ -4097,10 +4136,31 @@ static void __sched notrace __schedule(bool preempt)
update_rq_clock(rq);
switch_count = &prev->nivcsw;
- if (!preempt && prev->state) {
- if (signal_pending_state(prev->state, prev)) {
+ /*
+ * We must re-load prev->state in case ttwu_remote() changed it
+ * before we acquired rq->lock.
+ */
+ if (!preempt && prev_state && prev_state == prev->state) {
+ if (signal_pending_state(prev_state, prev)) {
prev->state = TASK_RUNNING;
} else {
+ prev->sched_contributes_to_load =
+ (prev_state & TASK_UNINTERRUPTIBLE) &&
+ !(prev_state & TASK_NOLOAD) &&
+ !(prev->flags & PF_FROZEN);
+
+ if (prev->sched_contributes_to_load)
+ rq->nr_uninterruptible++;
+
+ /*
+ * __schedule() ttwu()
+ * prev_state = prev->state; if (READ_ONCE(p->on_rq) && ...)
+ * LOCK rq->lock goto out;
+ * smp_mb__after_spinlock(); smp_acquire__after_ctrl_dep();
+ * p->on_rq = 0; p->state = TASK_WAKING;
+ *
+ * After this, schedule() must not care about p->state any more.
+ */
deactivate_task(rq, prev, DEQUEUE_SLEEP | DEQUEUE_NOCLOCK);
if (prev->in_iowait) {
@@ -4524,7 +4584,8 @@ void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task)
*/
if (dl_prio(prio)) {
if (!dl_prio(p->normal_prio) ||
- (pi_task && dl_entity_preempt(&pi_task->dl, &p->dl))) {
+ (pi_task && dl_prio(pi_task->prio) &&
+ dl_entity_preempt(&pi_task->dl, &p->dl))) {
p->dl.dl_boosted = 1;
queue_flag |= ENQUEUE_REPLENISH;
} else
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index c9cc1d6fa363..3862a28cd05d 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -2763,6 +2763,7 @@ void __dl_clear_params(struct task_struct *p)
dl_se->dl_bw = 0;
dl_se->dl_density = 0;
+ dl_se->dl_boosted = 0;
dl_se->dl_throttled = 0;
dl_se->dl_yielded = 0;
dl_se->dl_non_contending = 0;
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index b9b9f19e80c1..6fab1d17c575 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -806,7 +806,7 @@ void post_init_entity_util_avg(struct task_struct *p)
}
}
- sa->runnable_avg = cpu_scale;
+ sa->runnable_avg = sa->util_avg;
if (p->sched_class != &fair_sched_class) {
/*
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index 336d478bddc8..6bf34986f45c 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -96,6 +96,15 @@ void __cpuidle default_idle_call(void)
}
}
+static int call_cpuidle_s2idle(struct cpuidle_driver *drv,
+ struct cpuidle_device *dev)
+{
+ if (current_clr_polling_and_test())
+ return -EBUSY;
+
+ return cpuidle_enter_s2idle(drv, dev);
+}
+
static int call_cpuidle(struct cpuidle_driver *drv, struct cpuidle_device *dev,
int next_state)
{
@@ -171,11 +180,9 @@ static void cpuidle_idle_call(void)
if (idle_should_enter_s2idle()) {
rcu_idle_enter();
- entered_state = cpuidle_enter_s2idle(drv, dev);
- if (entered_state > 0) {
- local_irq_enable();
+ entered_state = call_cpuidle_s2idle(drv, dev);
+ if (entered_state > 0)
goto exit_idle;
- }
rcu_idle_exit();
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 549e7e6e0a66..5aa6661ecaf1 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1697,7 +1697,7 @@ static inline int task_on_rq_migrating(struct task_struct *p)
#define WF_SYNC 0x01 /* Waker goes to sleep after wakeup */
#define WF_FORK 0x02 /* Child wakeup after fork */
#define WF_MIGRATED 0x04 /* Internal use, task got migrated */
-#define WF_ON_RQ 0x08 /* Wakee is on_rq */
+#define WF_ON_CPU 0x08 /* Wakee is on_cpu */
/*
* To aid in avoiding the subversion of "niceness" due to uneven distribution