Dear RT folks!
I'm pleased to announce the v4.9.33-rt23 patch set.
Changes since v4.9.33-rt22:
- A changed CPU mask while a task was in a migrate_disable() section
did not run all its scheduler hooks after a migrate_enable(). Also
it did not immediatelly switch the CPU if its CPU mask was did not
contain the current CPU mask. Noticed while re-doing the migrate
disable code for v4.11 and also reported by Daniel Bristot.
- The removal of TASK_ALL in the last release uncovered a bug where we
mixed normal wake ups and wake ups made for waiters of sleeping
spinlock. Reported by Mike Galbraith.
Known issues
- CPU hotplug got a little better but can deadlock.
The delta patch against v4.9.33-rt22 is appended below and can be found here:
https://cdn.kernel.org/pub/linux/kernel/projects/rt/4.9/incr/patch-4.9.33-rt22-rt23.patch.xz
You can get this release via the git tree at:
git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git
v4.9.33-rt23
The RT patch against v4.9.33 can be found here:
https://cdn.kernel.org/pub/linux/kernel/projects/rt/4.9/older/patch-4.9.33-rt23.patch.xz
The split quilt queue is available at:
https://cdn.kernel.org/pub/linux/kernel/projects/rt/4.9/older/patches-4.9.33-rt23.tar.xz
Sebastian
diff --git a/include/linux/sched.h b/include/linux/sched.h
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1014,8 +1014,20 @@ struct wake_q_head {
#define WAKE_Q(name) \
struct wake_q_head name = { WAKE_Q_TAIL, &name.first }
-extern void wake_q_add(struct wake_q_head *head,
- struct task_struct *task);
+extern void __wake_q_add(struct wake_q_head *head,
+ struct task_struct *task, bool sleeper);
+static inline void wake_q_add(struct wake_q_head *head,
+ struct task_struct *task)
+{
+ __wake_q_add(head, task, false);
+}
+
+static inline void wake_q_add_sleeper(struct wake_q_head *head,
+ struct task_struct *task)
+{
+ __wake_q_add(head, task, true);
+}
+
extern void __wake_up_q(struct wake_q_head *head, bool sleeper);
static inline void wake_up_q(struct wake_q_head *head)
@@ -1535,6 +1547,7 @@ struct task_struct {
unsigned int policy;
#ifdef CONFIG_PREEMPT_RT_FULL
int migrate_disable;
+ int migrate_disable_update;
# ifdef CONFIG_SCHED_DEBUG
int migrate_disable_atomic;
# endif
@@ -1745,6 +1758,7 @@ struct task_struct {
raw_spinlock_t pi_lock;
struct wake_q_node wake_q;
+ struct wake_q_node wake_q_sleeper;
#ifdef CONFIG_RT_MUTEXES
/* PI waiters blocked on a rt_mutex held by this task */
diff --git a/kernel/fork.c b/kernel/fork.c
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -558,6 +558,7 @@ static struct task_struct *dup_task_struct(struct
task_struct *orig, int node)
tsk->splice_pipe = NULL;
tsk->task_frag.page = NULL;
tsk->wake_q.next = NULL;
+ tsk->wake_q_sleeper.next = NULL;
account_kernel_stack(tsk, 1);
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1506,7 +1506,7 @@ static void mark_wakeup_next_waiter(struct wake_q_head
*wake_q,
*/
preempt_disable();
if (waiter->savestate)
- wake_q_add(wake_sleeper_q, waiter->task);
+ wake_q_add_sleeper(wake_sleeper_q, waiter->task);
else
wake_q_add(wake_q, waiter->task);
raw_spin_unlock(¤t->pi_lock);
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -430,9 +430,15 @@ static bool set_nr_if_polling(struct task_struct *p)
#endif
#endif
-void wake_q_add(struct wake_q_head *head, struct task_struct *task)
+void __wake_q_add(struct wake_q_head *head, struct task_struct *task,
+ bool sleeper)
{
- struct wake_q_node *node = &task->wake_q;
+ struct wake_q_node *node;
+
+ if (sleeper)
+ node = &task->wake_q_sleeper;
+ else
+ node = &task->wake_q;
/*
* Atomically grab the task, if ->wake_q is !nil already it means
@@ -461,11 +467,17 @@ void __wake_up_q(struct wake_q_head *head, bool sleeper)
while (node != WAKE_Q_TAIL) {
struct task_struct *task;
- task = container_of(node, struct task_struct, wake_q);
+ if (sleeper)
+ task = container_of(node, struct task_struct,
wake_q_sleeper);
+ else
+ task = container_of(node, struct task_struct, wake_q);
BUG_ON(!task);
/* task can safely be re-inserted now */
node = node->next;
- task->wake_q.next = NULL;
+ if (sleeper)
+ task->wake_q_sleeper.next = NULL;
+ else
+ task->wake_q.next = NULL;
/*
* wake_up_process() implies a wmb() to pair with the queueing
@@ -1138,18 +1150,14 @@ void set_cpus_allowed_common(struct task_struct *p,
const struct cpumask *new_ma
p->nr_cpus_allowed = cpumask_weight(new_mask);
}
-void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
+static void __do_set_cpus_allowed_tail(struct task_struct *p,
+ const struct cpumask *new_mask)
{
struct rq *rq = task_rq(p);
bool queued, running;
lockdep_assert_held(&p->pi_lock);
- if (__migrate_disabled(p)) {
- cpumask_copy(&p->cpus_allowed, new_mask);
- return;
- }
-
queued = task_on_rq_queued(p);
running = task_current(rq, p);
@@ -1172,6 +1180,20 @@ void do_set_cpus_allowed(struct task_struct *p, const
struct cpumask *new_mask)
set_curr_task(rq, p);
}
+void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
+{
+ if (__migrate_disabled(p)) {
+ lockdep_assert_held(&p->pi_lock);
+
+ cpumask_copy(&p->cpus_allowed, new_mask);
+#if defined(CONFIG_PREEMPT_RT_FULL) && defined(CONFIG_SMP)
+ p->migrate_disable_update = 1;
+#endif
+ return;
+ }
+ __do_set_cpus_allowed_tail(p, new_mask);
+}
+
static DEFINE_PER_CPU(struct cpumask, sched_cpumasks);
static DEFINE_MUTEX(sched_down_mutex);
static cpumask_t sched_down_cpumask;
@@ -3435,6 +3457,43 @@ void migrate_enable(void)
*/
p->migrate_disable = 0;
+ if (p->migrate_disable_update) {
+ struct rq *rq;
+ struct rq_flags rf;
+
+ rq = task_rq_lock(p, &rf);
+ update_rq_clock(rq);
+
+ __do_set_cpus_allowed_tail(p, &p->cpus_allowed);
+ task_rq_unlock(rq, p, &rf);
+
+ p->migrate_disable_update = 0;
+
+ WARN_ON(smp_processor_id() != task_cpu(p));
+ if (!cpumask_test_cpu(task_cpu(p), &p->cpus_allowed)) {
+ const struct cpumask *cpu_valid_mask = cpu_active_mask;
+ struct migration_arg arg;
+ unsigned int dest_cpu;
+
+ if (p->flags & PF_KTHREAD) {
+ /*
+ * Kernel threads are allowed on online &&
!active CPUs
+ */
+ cpu_valid_mask = cpu_online_mask;
+ }
+ dest_cpu = cpumask_any_and(cpu_valid_mask,
&p->cpus_allowed);
+ arg.task = p;
+ arg.dest_cpu = dest_cpu;
+
+ unpin_current_cpu();
+ preempt_lazy_enable();
+ preempt_enable();
+ stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
+ tlb_migrate_finish(p->mm);
+ return;
+ }
+ }
+
unpin_current_cpu();
preempt_enable();
preempt_lazy_enable();
diff --git a/localversion-rt b/localversion-rt
--- a/localversion-rt
+++ b/localversion-rt
@@ -1 +1 @@
--rt22
+-rt23
