[GIT PULL] scheduler fixes

Ingo Molnar
2009-12-18T18:55:24Z

Linus,

Please pull the latest sched-fixes-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git sched-fixes-for-linus

These contain some difficult race fixes from Peter - would be nice to pull
them early in the -rc2 cycle, in case there's any problems with them.

Thanks,

Ingo

------------------>
David Miller (1):
sched: Fix cpu_clock() in NMIs, on !CONFIG_HAVE_UNSTABLE_SCHED_CLOCK

Frederic Weisbecker (1):
sched: Teach might_sleep() about preemptible RCU

Ingo Molnar (1):
sched: Make warning less noisy

Joe Perches (1):
sched: Use pr_fmt() and pr_<level>()

Peter Zijlstra (16):
sched: Mark boot-cpu active before smp_init()
sched: Fix task_hot() test order
sched: Select_task_rq_fair() must honour SD_LOAD_BALANCE
sched: Use TASK_WAKING for fork wakups
sched: Ensure set_task_cpu() is never called on blocked tasks
sched: Fix sched_exec() balancing
sched: Fix select_task_rq() vs hotplug issues
sched: Move kthread_bind() back to kthread.c
sched: Add pre and post wakeup hooks
sched: Remove the cfs_rq dependency from set_task_cpu()
sched: Simplify set_task_cpu()
sched: Move TASK_STATE_TO_CHAR_STR near the TASK_state bits
sched: Add missing state chars to TASK_STATE_TO_CHAR_STR
sched: Update task_state_arraypwith new states
sched: Assert task state bits at build time
sched: Fix broken assertion

Rafael J. Wysocki (1):
sched: Make wakeup side and atomic variants of completion API irq safe

Thomas Gleixner (3):
sched: Use rcu in sys_sched_getscheduler/sys_sched_getparam()
sched: Use rcu in sched_get/set_affinity()
sched: Use rcu in sched_get_rr_param()

Xiaotian Feng (1):
sched: Fix set_cpu_active() in cpu_down()

fs/proc/array.c | 19 ++-
include/linux/rcutiny.h | 5 +
include/linux/rcutree.h | 11 ++
include/linux/sched.h | 13 +-
init/main.c | 7 +-
kernel/cpu.c | 24 +---
kernel/kthread.c | 23 +++
kernel/sched.c | 401 ++++++++++++++++++++++++-----------------------
kernel/sched_clock.c | 23 ++-
kernel/sched_fair.c | 53 ++++++-
kernel/sched_idletask.c | 2 +-
kernel/sched_rt.c | 4 +-
12 files changed, 336 insertions(+), 249 deletions(-)

diff --git a/fs/proc/array.c b/fs/proc/array.c
index 4badde1..f560325 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -134,13 +134,16 @@ static inline void task_name(struct seq_file *m, struct task_struct *p)
* simple bit tests.
*/
static const char *task_state_array[] = {
- "R (running)", /* 0 */
- "S (sleeping)", /* 1 */
- "D (disk sleep)", /* 2 */
- "T (stopped)", /* 4 */
- "T (tracing stop)", /* 8 */
- "Z (zombie)", /* 16 */
- "X (dead)" /* 32 */
+ "R (running)", /* 0 */
+ "S (sleeping)", /* 1 */
+ "D (disk sleep)", /* 2 */
+ "T (stopped)", /* 4 */
+ "t (tracing stop)", /* 8 */
+ "Z (zombie)", /* 16 */
+ "X (dead)", /* 32 */
+ "x (dead)", /* 64 */
+ "K (wakekill)", /* 128 */
+ "W (waking)", /* 256 */
};

static inline const char *get_task_state(struct task_struct *tsk)
@@ -148,6 +151,8 @@ static inline const char *get_task_state(struct task_struct *tsk)
unsigned int state = (tsk->state & TASK_REPORT) | tsk->exit_state;
const char **p = &task_state_array[0];

+ BUILD_BUG_ON(1 + ilog2(TASK_STATE_MAX) != ARRAY_SIZE(task_state_array));
+
while (state) {
p++;
state >>= 1;
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index c4ba9a7..96cc307 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -101,4 +101,9 @@ static inline void exit_rcu(void)
{
}

+static inline int rcu_preempt_depth(void)
+{
+ return 0;
+}
+
#endif /* __LINUX_RCUTINY_H */
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index c93eee5..8044b1b 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -45,6 +45,12 @@ extern void __rcu_read_unlock(void);
extern void synchronize_rcu(void);
extern void exit_rcu(void);

+/*
+ * Defined as macro as it is a very low level header
+ * included from areas that don't even know about current
+ */
+#define rcu_preempt_depth() (current->rcu_read_lock_nesting)
+
#else /* #ifdef CONFIG_TREE_PREEMPT_RCU */

static inline void __rcu_read_lock(void)
@@ -63,6 +69,11 @@ static inline void exit_rcu(void)
{
}

+static inline int rcu_preempt_depth(void)
+{
+ return 0;
+}
+
#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */

static inline void __rcu_read_lock_bh(void)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 5c858f3..3754387 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -192,6 +192,12 @@ print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
#define TASK_DEAD 64
#define TASK_WAKEKILL 128
#define TASK_WAKING 256
+#define TASK_STATE_MAX 512
+
+#define TASK_STATE_TO_CHAR_STR "RSDTtZXxKW"
+
+extern char ___assert_task_state[1 - 2*!!(
+ sizeof(TASK_STATE_TO_CHAR_STR)-1 != ilog2(TASK_STATE_MAX)+1)];

/* Convenience macros for the sake of set_task_state */
#define TASK_KILLABLE (TASK_WAKEKILL | TASK_UNINTERRUPTIBLE)
@@ -1091,7 +1097,8 @@ struct sched_class {
enum cpu_idle_type idle);
void (*pre_schedule) (struct rq *this_rq, struct task_struct *task);
void (*post_schedule) (struct rq *this_rq);
- void (*task_wake_up) (struct rq *this_rq, struct task_struct *task);
+ void (*task_waking) (struct rq *this_rq, struct task_struct *task);
+ void (*task_woken) (struct rq *this_rq, struct task_struct *task);

void (*set_cpus_allowed)(struct task_struct *p,
const struct cpumask *newmask);
@@ -1115,7 +1122,7 @@ struct sched_class {
struct task_struct *task);

#ifdef CONFIG_FAIR_GROUP_SCHED
- void (*moved_group) (struct task_struct *p);
+ void (*moved_group) (struct task_struct *p, int on_rq);
#endif
};

@@ -2594,8 +2601,6 @@ static inline void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
}
#endif /* CONFIG_MM_OWNER */

-#define TASK_STATE_TO_CHAR_STR "RSDTtZX"
-
#endif /* __KERNEL__ */

#endif
diff --git a/init/main.c b/init/main.c
index c3db4a9..dac44a9 100644
--- a/init/main.c
+++ b/init/main.c
@@ -369,12 +369,6 @@ static void __init smp_init(void)
{
unsigned int cpu;

- /*
- * Set up the current CPU as possible to migrate to.
- * The other ones will be done by cpu_up/cpu_down()
- */
- set_cpu_active(smp_processor_id(), true);
-
/* FIXME: This should be done in userspace --RR */
for_each_present_cpu(cpu) {
if (num_online_cpus() >= setup_max_cpus)
@@ -486,6 +480,7 @@ static void __init boot_cpu_init(void)
int cpu = smp_processor_id();
/* Mark the boot cpu "present", "online" etc for SMP and UP case */
set_cpu_online(cpu, true);
+ set_cpu_active(cpu, true);
set_cpu_present(cpu, true);
set_cpu_possible(cpu, true);
}
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 291ac58..1c8ddd6 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -209,6 +209,7 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
return -ENOMEM;

cpu_hotplug_begin();
+ set_cpu_active(cpu, false);
err = __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE | mod,
hcpu, -1, &nr_calls);
if (err == NOTIFY_BAD) {
@@ -280,18 +281,6 @@ int __ref cpu_down(unsigned int cpu)
goto out;
}

- set_cpu_active(cpu, false);
-
- /*
- * Make sure the all cpus did the reschedule and are not
- * using stale version of the cpu_active_mask.
- * This is not strictly necessary becuase stop_machine()
- * that we run down the line already provides the required
- * synchronization. But it's really a side effect and we do not
- * want to depend on the innards of the stop_machine here.
- */
- synchronize_sched();
-
err = _cpu_down(cpu, 0);

out:
@@ -382,19 +371,12 @@ int disable_nonboot_cpus(void)
return error;
cpu_maps_update_begin();
first_cpu = cpumask_first(cpu_online_mask);
- /* We take down all of the non-boot CPUs in one shot to avoid races
+ /*
+ * We take down all of the non-boot CPUs in one shot to avoid races
* with the userspace trying to use the CPU hotplug at the same time
*/
cpumask_clear(frozen_cpus);

- for_each_online_cpu(cpu) {
- if (cpu == first_cpu)
- continue;
- set_cpu_active(cpu, false);
- }
-
- synchronize_sched();
-
printk("Disabling non-boot CPUs ...\n");
for_each_online_cpu(cpu) {
if (cpu == first_cpu)
diff --git a/kernel/kthread.c b/kernel/kthread.c
index ab7ae57..fbb6222 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -150,6 +150,29 @@ struct task_struct *kthread_create(int (*threadfn)(void *data),
EXPORT_SYMBOL(kthread_create);

/**
+ * kthread_bind - bind a just-created kthread to a cpu.
+ * @p: thread created by kthread_create().
+ * @cpu: cpu (might not be online, must be possible) for @k to run on.
+ *
+ * Description: This function is equivalent to set_cpus_allowed(),
+ * except that @cpu doesn't need to be online, and the thread must be
+ * stopped (i.e., just returned from kthread_create()).
+ */
+void kthread_bind(struct task_struct *p, unsigned int cpu)
+{
+ /* Must have done schedule() in kthread() before we set_task_cpu */
+ if (!wait_task_inactive(p, TASK_UNINTERRUPTIBLE)) {
+ WARN_ON(1);
+ return;
+ }
+
+ p->cpus_allowed = cpumask_of_cpu(cpu);
+ p->rt.nr_cpus_allowed = 1;
+ p->flags |= PF_THREAD_BOUND;
+}
+EXPORT_SYMBOL(kthread_bind);
+
+/**
* kthread_stop - stop a thread created by kthread_create().
* @k: thread created by kthread_create().
*
diff --git a/kernel/sched.c b/kernel/sched.c
index 18cceee..720df10 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -26,6 +26,8 @@
* Thomas Gleixner, Mike Kravetz
*/

+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/nmi.h>
@@ -2002,39 +2004,6 @@ static inline void check_class_changed(struct rq *rq, struct task_struct *p,
p->sched_class->prio_changed(rq, p, oldprio, running);
}

-/**
- * kthread_bind - bind a just-created kthread to a cpu.
- * @p: thread created by kthread_create().
- * @cpu: cpu (might not be online, must be possible) for @k to run on.
- *
- * Description: This function is equivalent to set_cpus_allowed(),
- * except that @cpu doesn't need to be online, and the thread must be
- * stopped (i.e., just returned from kthread_create()).
- *
- * Function lives here instead of kthread.c because it messes with
- * scheduler internals which require locking.
- */
-void kthread_bind(struct task_struct *p, unsigned int cpu)
-{
- struct rq *rq = cpu_rq(cpu);
- unsigned long flags;
-
- /* Must have done schedule() in kthread() before we set_task_cpu */
- if (!wait_task_inactive(p, TASK_UNINTERRUPTIBLE)) {
- WARN_ON(1);
- return;
- }
-
- raw_spin_lock_irqsave(&rq->lock, flags);
- update_rq_clock(rq);
- set_task_cpu(p, cpu);
- p->cpus_allowed = cpumask_of_cpu(cpu);
- p->rt.nr_cpus_allowed = 1;
- p->flags |= PF_THREAD_BOUND;
- raw_spin_unlock_irqrestore(&rq->lock, flags);
-}
-EXPORT_SYMBOL(kthread_bind);
-
#ifdef CONFIG_SMP
/*
* Is this task likely cache-hot:
@@ -2044,6 +2013,9 @@ task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
{
s64 delta;

+ if (p->sched_class != &fair_sched_class)
+ return 0;
+
/*
* Buddy candidates are cache hot:
*/
@@ -2052,9 +2024,6 @@ task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
&p->se == cfs_rq_of(&p->se)->last))
return 1;

- if (p->sched_class != &fair_sched_class)
- return 0;
-
if (sysctl_sched_migration_cost == -1)
return 1;
if (sysctl_sched_migration_cost == 0)
@@ -2065,22 +2034,24 @@ task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
return delta < (s64)sysctl_sched_migration_cost;
}

-
void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
{
- int old_cpu = task_cpu(p);
- struct cfs_rq *old_cfsrq = task_cfs_rq(p),
- *new_cfsrq = cpu_cfs_rq(old_cfsrq, new_cpu);
+#ifdef CONFIG_SCHED_DEBUG
+ /*
+ * We should never call set_task_cpu() on a blocked task,
+ * ttwu() will sort out the placement.
+ */
+ WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
+ !(task_thread_info(p)->preempt_count & PREEMPT_ACTIVE));
+#endif

trace_sched_migrate_task(p, new_cpu);

- if (old_cpu != new_cpu) {
- p->se.nr_migrations++;
- perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS,
- 1, 1, NULL, 0);
- }
- p->se.vruntime -= old_cfsrq->min_vruntime -
- new_cfsrq->min_vruntime;
+ if (task_cpu(p) == new_cpu)
+ return;
+
+ p->se.nr_migrations++;
+ perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, 1, NULL, 0);

__set_task_cpu(p, new_cpu);
}
@@ -2105,13 +2076,10 @@ migrate_task(struct task_struct *p, int dest_cpu, struct migration_req *req)

/*
* If the task is not on a runqueue (and not running), then
- * it is sufficient to simply update the task's cpu field.
+ * the next wake-up will properly place the task.
*/
- if (!p->se.on_rq && !task_running(rq, p)) {
- update_rq_clock(rq);
- set_task_cpu(p, dest_cpu);
+ if (!p->se.on_rq && !task_running(rq, p))
return 0;
- }

init_completion(&req->done);
req->task = p;
@@ -2317,10 +2285,73 @@ void task_oncpu_function_call(struct task_struct *p,
}

#ifdef CONFIG_SMP
+static int select_fallback_rq(int cpu, struct task_struct *p)
+{
+ int dest_cpu;
+ const struct cpumask *nodemask = cpumask_of_node(cpu_to_node(cpu));
+
+ /* Look for allowed, online CPU in same node. */
+ for_each_cpu_and(dest_cpu, nodemask, cpu_active_mask)
+ if (cpumask_test_cpu(dest_cpu, &p->cpus_allowed))
+ return dest_cpu;
+
+ /* Any allowed, online CPU? */
+ dest_cpu = cpumask_any_and(&p->cpus_allowed, cpu_active_mask);
+ if (dest_cpu < nr_cpu_ids)
+ return dest_cpu;
+
+ /* No more Mr. Nice Guy. */
+ if (dest_cpu >= nr_cpu_ids) {
+ rcu_read_lock();
+ cpuset_cpus_allowed_locked(p, &p->cpus_allowed);
+ rcu_read_unlock();
+ dest_cpu = cpumask_any_and(cpu_active_mask, &p->cpus_allowed);
+
+ /*
+ * Don't tell them about moving exiting tasks or
+ * kernel threads (both mm NULL), since they never
+ * leave kernel.
+ */
+ if (p->mm && printk_ratelimit()) {
+ printk(KERN_INFO "process %d (%s) no "
+ "longer affine to cpu%d\n",
+ task_pid_nr(p), p->comm, cpu);
+ }
+ }
+
+ return dest_cpu;
+}
+
+/*
+ * Called from:
+ *
+ * - fork, @p is stable because it isn't on the tasklist yet
+ *
+ * - exec, @p is unstable, retry loop
+ *
+ * - wake-up, we serialize ->cpus_allowed against TASK_WAKING so
+ * we should be good.
+ */
static inline
int select_task_rq(struct task_struct *p, int sd_flags, int wake_flags)
{
- return p->sched_class->select_task_rq(p, sd_flags, wake_flags);
+ int cpu = p->sched_class->select_task_rq(p, sd_flags, wake_flags);
+
+ /*
+ * In order not to call set_task_cpu() on a blocking task we need
+ * to rely on ttwu() to place the task on a valid ->cpus_allowed
+ * cpu.
+ *
+ * Since this is common to all placement strategies, this lives here.
+ *
+ * [ this allows ->select_task() to simply return task_cpu(p) and
+ * not worry about this generic constraint ]
+ */
+ if (unlikely(!cpumask_test_cpu(cpu, &p->cpus_allowed) ||
+ !cpu_active(cpu)))
+ cpu = select_fallback_rq(task_cpu(p), p);
+
+ return cpu;
}
#endif

@@ -2375,6 +2406,10 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state,
if (task_contributes_to_load(p))
rq->nr_uninterruptible--;
p->state = TASK_WAKING;
+
+ if (p->sched_class->task_waking)
+ p->sched_class->task_waking(rq, p);
+
__task_rq_unlock(rq);

cpu = select_task_rq(p, SD_BALANCE_WAKE, wake_flags);
@@ -2438,8 +2473,8 @@ out_running:

p->state = TASK_RUNNING;
#ifdef CONFIG_SMP
- if (p->sched_class->task_wake_up)
- p->sched_class->task_wake_up(rq, p);
+ if (p->sched_class->task_woken)
+ p->sched_class->task_woken(rq, p);

if (unlikely(rq->idle_stamp)) {
u64 delta = rq->clock - rq->idle_stamp;
@@ -2538,14 +2573,6 @@ static void __sched_fork(struct task_struct *p)
#ifdef CONFIG_PREEMPT_NOTIFIERS
INIT_HLIST_HEAD(&p->preempt_notifiers);
#endif
-
- /*
- * We mark the process as running here, but have not actually
- * inserted it onto the runqueue yet. This guarantees that
- * nobody will actually run it, and a signal or other external
- * event cannot wake it up and insert it on the runqueue either.
- */
- p->state = TASK_RUNNING;
}

/*
@@ -2556,6 +2583,12 @@ void sched_fork(struct task_struct *p, int clone_flags)
int cpu = get_cpu();

__sched_fork(p);
+ /*
+ * We mark the process as waking here. This guarantees that
+ * nobody will actually run it, and a signal or other external
+ * event cannot wake it up and insert it on the runqueue either.
+ */
+ p->state = TASK_WAKING;

/*
* Revert to default priority/policy on fork if requested.
@@ -2624,14 +2657,15 @@ void wake_up_new_task(struct task_struct *p, unsigned long clone_flags)
struct rq *rq;

rq = task_rq_lock(p, &flags);
- BUG_ON(p->state != TASK_RUNNING);
+ BUG_ON(p->state != TASK_WAKING);
+ p->state = TASK_RUNNING;
update_rq_clock(rq);
activate_task(rq, p, 0);
trace_sched_wakeup_new(rq, p, 1);
check_preempt_curr(rq, p, WF_FORK);
#ifdef CONFIG_SMP
- if (p->sched_class->task_wake_up)
- p->sched_class->task_wake_up(rq, p);
+ if (p->sched_class->task_woken)
+ p->sched_class->task_woken(rq, p);
#endif
task_rq_unlock(rq, &flags);
}
@@ -3101,21 +3135,36 @@ static void double_rq_unlock(struct rq *rq1, struct rq *rq2)
}

/*
- * If dest_cpu is allowed for this process, migrate the task to it.
- * This is accomplished by forcing the cpu_allowed mask to only
- * allow dest_cpu, which will force the cpu onto dest_cpu. Then
- * the cpu_allowed mask is restored.
+ * sched_exec - execve() is a valuable balancing opportunity, because at
+ * this point the task has the smallest effective memory and cache footprint.
*/
-static void sched_migrate_task(struct task_struct *p, int dest_cpu)
+void sched_exec(void)
{
+ struct task_struct *p = current;
struct migration_req req;
+ int dest_cpu, this_cpu;
unsigned long flags;
struct rq *rq;

+again:
+ this_cpu = get_cpu();
+ dest_cpu = select_task_rq(p, SD_BALANCE_EXEC, 0);
+ if (dest_cpu == this_cpu) {
+ put_cpu();
+ return;
+ }
+
rq = task_rq_lock(p, &flags);
+ put_cpu();
+
+ /*
+ * select_task_rq() can race against ->cpus_allowed
+ */
if (!cpumask_test_cpu(dest_cpu, &p->cpus_allowed)
- || unlikely(!cpu_active(dest_cpu)))
- goto out;
+ || unlikely(!cpu_active(dest_cpu))) {
+ task_rq_unlock(rq, &flags);
+ goto again;
+ }

/* force the process onto the specified CPU */
if (migrate_task(p, dest_cpu, &req)) {
@@ -3130,24 +3179,10 @@ static void sched_migrate_task(struct task_struct *p, int dest_cpu)

return;
}
-out:
task_rq_unlock(rq, &flags);
}

/*
- * sched_exec - execve() is a valuable balancing opportunity, because at
- * this point the task has the smallest effective memory and cache footprint.
- */
-void sched_exec(void)
-{
- int new_cpu, this_cpu = get_cpu();
- new_cpu = select_task_rq(current, SD_BALANCE_EXEC, 0);
- put_cpu();
- if (new_cpu != this_cpu)
- sched_migrate_task(current, new_cpu);
-}
-
-/*
* pull_task - move a task from a remote runqueue to the local runqueue.
* Both runqueues must be locked.
*/
@@ -5340,8 +5375,8 @@ static noinline void __schedule_bug(struct task_struct *prev)
{
struct pt_regs *regs = get_irq_regs();

- printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
- prev->comm, prev->pid, preempt_count());
+ pr_err("BUG: scheduling while atomic: %s/%d/0x%08x\n",
+ prev->comm, prev->pid, preempt_count());

debug_show_held_locks(prev);
print_modules();
@@ -5911,14 +5946,15 @@ EXPORT_SYMBOL(wait_for_completion_killable);
*/
bool try_wait_for_completion(struct completion *x)
{
+ unsigned long flags;
int ret = 1;

- spin_lock_irq(&x->wait.lock);
+ spin_lock_irqsave(&x->wait.lock, flags);
if (!x->done)
ret = 0;
else
x->done--;
- spin_unlock_irq(&x->wait.lock);
+ spin_unlock_irqrestore(&x->wait.lock, flags);
return ret;
}
EXPORT_SYMBOL(try_wait_for_completion);
@@ -5933,12 +5969,13 @@ EXPORT_SYMBOL(try_wait_for_completion);
*/
bool completion_done(struct completion *x)
{
+ unsigned long flags;
int ret = 1;

- spin_lock_irq(&x->wait.lock);
+ spin_lock_irqsave(&x->wait.lock, flags);
if (!x->done)
ret = 0;
- spin_unlock_irq(&x->wait.lock);
+ spin_unlock_irqrestore(&x->wait.lock, flags);
return ret;
}
EXPORT_SYMBOL(completion_done);
@@ -6457,7 +6494,7 @@ SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
return -EINVAL;

retval = -ESRCH;
- read_lock(&tasklist_lock);
+ rcu_read_lock();
p = find_process_by_pid(pid);
if (p) {
retval = security_task_getscheduler(p);
@@ -6465,7 +6502,7 @@ SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
retval = p->policy
| (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
}
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
return retval;
}

@@ -6483,7 +6520,7 @@ SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
if (!param || pid < 0)
return -EINVAL;

- read_lock(&tasklist_lock);
+ rcu_read_lock();
p = find_process_by_pid(pid);
retval = -ESRCH;
if (!p)
@@ -6494,7 +6531,7 @@ SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
goto out_unlock;

lp.sched_priority = p->rt_priority;
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();

/*
* This one might sleep, we cannot do it with a spinlock held ...
@@ -6504,7 +6541,7 @@ SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
return retval;

out_unlock:
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
return retval;
}

@@ -6515,22 +6552,18 @@ long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
int retval;

get_online_cpus();
- read_lock(&tasklist_lock);
+ rcu_read_lock();

p = find_process_by_pid(pid);
if (!p) {
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
put_online_cpus();
return -ESRCH;
}

- /*
- * It is not safe to call set_cpus_allowed with the
- * tasklist_lock held. We will bump the task_struct's
- * usage count and then drop tasklist_lock.
- */
+ /* Prevent p going away */
get_task_struct(p);
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();

if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
retval = -ENOMEM;
@@ -6616,7 +6649,7 @@ long sched_getaffinity(pid_t pid, struct cpumask *mask)
int retval;

get_online_cpus();
- read_lock(&tasklist_lock);
+ rcu_read_lock();

retval = -ESRCH;
p = find_process_by_pid(pid);
@@ -6632,7 +6665,7 @@ long sched_getaffinity(pid_t pid, struct cpumask *mask)
task_rq_unlock(rq, &flags);

out_unlock:
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
put_online_cpus();

return retval;
@@ -6876,7 +6909,7 @@ SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
return -EINVAL;

retval = -ESRCH;
- read_lock(&tasklist_lock);
+ rcu_read_lock();
p = find_process_by_pid(pid);
if (!p)
goto out_unlock;
@@ -6889,13 +6922,13 @@ SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
time_slice = p->sched_class->get_rr_interval(rq, p);
task_rq_unlock(rq, &flags);

- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
jiffies_to_timespec(time_slice, &t);
retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
return retval;

out_unlock:
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
return retval;
}

@@ -6907,23 +6940,23 @@ void sched_show_task(struct task_struct *p)
unsigned state;

state = p->state ? __ffs(p->state) + 1 : 0;
- printk(KERN_INFO "%-13.13s %c", p->comm,
+ pr_info("%-13.13s %c", p->comm,
state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
#if BITS_PER_LONG == 32
if (state == TASK_RUNNING)
- printk(KERN_CONT " running ");
+ pr_cont(" running ");
else
- printk(KERN_CONT " %08lx ", thread_saved_pc(p));
+ pr_cont(" %08lx ", thread_saved_pc(p));
#else
if (state == TASK_RUNNING)
- printk(KERN_CONT " running task ");
+ pr_cont(" running task ");
else
- printk(KERN_CONT " %016lx ", thread_saved_pc(p));
+ pr_cont(" %016lx ", thread_saved_pc(p));
#endif
#ifdef CONFIG_DEBUG_STACK_USAGE
free = stack_not_used(p);
#endif
- printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free,
+ pr_cont("%5lu %5d %6d 0x%08lx\n", free,
task_pid_nr(p), task_pid_nr(p->real_parent),
(unsigned long)task_thread_info(p)->flags);

@@ -6935,11 +6968,9 @@ void show_state_filter(unsigned long state_filter)
struct task_struct *g, *p;

#if BITS_PER_LONG == 32
- printk(KERN_INFO
- " task PC stack pid father\n");
+ pr_info(" task PC stack pid father\n");
#else
- printk(KERN_INFO
- " task PC stack pid father\n");
+ pr_info(" task PC stack pid father\n");
#endif
read_lock(&tasklist_lock);
do_each_thread(g, p) {
@@ -6986,6 +7017,7 @@ void __cpuinit init_idle(struct task_struct *idle, int cpu)
raw_spin_lock_irqsave(&rq->lock, flags);

__sched_fork(idle);
+ idle->state = TASK_RUNNING;
idle->se.exec_start = sched_clock();

cpumask_copy(&idle->cpus_allowed, cpumask_of(cpu));
@@ -7100,7 +7132,23 @@ int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
struct rq *rq;
int ret = 0;

+ /*
+ * Since we rely on wake-ups to migrate sleeping tasks, don't change
+ * the ->cpus_allowed mask from under waking tasks, which would be
+ * possible when we change rq->lock in ttwu(), so synchronize against
+ * TASK_WAKING to avoid that.
+ */
+again:
+ while (p->state == TASK_WAKING)
+ cpu_relax();
+
rq = task_rq_lock(p, &flags);
+
+ if (p->state == TASK_WAKING) {
+ task_rq_unlock(rq, &flags);
+ goto again;
+ }
+
if (!cpumask_intersects(new_mask, cpu_active_mask)) {
ret = -EINVAL;
goto out;
@@ -7156,7 +7204,7 @@ EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
{
struct rq *rq_dest, *rq_src;
- int ret = 0, on_rq;
+ int ret = 0;

if (unlikely(!cpu_active(dest_cpu)))
return ret;
@@ -7172,12 +7220,13 @@ static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
if (!cpumask_test_cpu(dest_cpu, &p->cpus_allowed))
goto fail;

- on_rq = p->se.on_rq;
- if (on_rq)
+ /*
+ * If we're not on a rq, the next wake-up will ensure we're
+ * placed properly.
+ */
+ if (p->se.on_rq) {
deactivate_task(rq_src, p, 0);
-
- set_task_cpu(p, dest_cpu);
- if (on_rq) {
+ set_task_cpu(p, dest_cpu);
activate_task(rq_dest, p, 0);
check_preempt_curr(rq_dest, p, 0);
}
@@ -7273,37 +7322,10 @@ static int __migrate_task_irq(struct task_struct *p, int src_cpu, int dest_cpu)
static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *p)
{
int dest_cpu;
- const struct cpumask *nodemask = cpumask_of_node(cpu_to_node(dead_cpu));

again:
- /* Look for allowed, online CPU in same node. */
- for_each_cpu_and(dest_cpu, nodemask, cpu_active_mask)
- if (cpumask_test_cpu(dest_cpu, &p->cpus_allowed))
- goto move;
-
- /* Any allowed, online CPU? */
- dest_cpu = cpumask_any_and(&p->cpus_allowed, cpu_active_mask);
- if (dest_cpu < nr_cpu_ids)
- goto move;
-
- /* No more Mr. Nice Guy. */
- if (dest_cpu >= nr_cpu_ids) {
- cpuset_cpus_allowed_locked(p, &p->cpus_allowed);
- dest_cpu = cpumask_any_and(cpu_active_mask, &p->cpus_allowed);
-
- /*
- * Don't tell them about moving exiting tasks or
- * kernel threads (both mm NULL), since they never
- * leave kernel.
- */
- if (p->mm && printk_ratelimit()) {
- printk(KERN_INFO "process %d (%s) no "
- "longer affine to cpu%d\n",
- task_pid_nr(p), p->comm, dead_cpu);
- }
- }
+ dest_cpu = select_fallback_rq(dead_cpu, p);

-move:
/* It can have affinity changed while we were choosing. */
if (unlikely(!__migrate_task_irq(p, dead_cpu, dest_cpu)))
goto again;
@@ -7806,48 +7828,44 @@ static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
printk(KERN_DEBUG "%*s domain %d: ", level, "", level);

if (!(sd->flags & SD_LOAD_BALANCE)) {
- printk("does not load-balance\n");
+ pr_cont("does not load-balance\n");
if (sd->parent)
- printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
- " has parent");
+ pr_err("ERROR: !SD_LOAD_BALANCE domain has parent\n");
return -1;
}

- printk(KERN_CONT "span %s level %s\n", str, sd->name);
+ pr_cont("span %s level %s\n", str, sd->name);

if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
- printk(KERN_ERR "ERROR: domain->span does not contain "
- "CPU%d\n", cpu);
+ pr_err("ERROR: domain->span does not contain CPU%d\n", cpu);
}
if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) {
- printk(KERN_ERR "ERROR: domain->groups does not contain"
- " CPU%d\n", cpu);
+ pr_err("ERROR: domain->groups does not contain CPU%d\n", cpu);
}

printk(KERN_DEBUG "%*s groups:", level + 1, "");
do {
if (!group) {
- printk("\n");
- printk(KERN_ERR "ERROR: group is NULL\n");
+ pr_cont("\n");
+ pr_err("ERROR: group is NULL\n");
break;
}

if (!group->cpu_power) {
- printk(KERN_CONT "\n");
- printk(KERN_ERR "ERROR: domain->cpu_power not "
- "set\n");
+ pr_cont("\n");
+ pr_err("ERROR: domain->cpu_power not set\n");
break;
}

if (!cpumask_weight(sched_group_cpus(group))) {
- printk(KERN_CONT "\n");
- printk(KERN_ERR "ERROR: empty group\n");
+ pr_cont("\n");
+ pr_err("ERROR: empty group\n");
break;
}

if (cpumask_intersects(groupmask, sched_group_cpus(group))) {
- printk(KERN_CONT "\n");
- printk(KERN_ERR "ERROR: repeated CPUs\n");
+ pr_cont("\n");
+ pr_err("ERROR: repeated CPUs\n");
break;
}

@@ -7855,23 +7873,21 @@ static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,

cpulist_scnprintf(str, sizeof(str), sched_group_cpus(group));

- printk(KERN_CONT " %s", str);
+ pr_cont(" %s", str);
if (group->cpu_power != SCHED_LOAD_SCALE) {
- printk(KERN_CONT " (cpu_power = %d)",
- group->cpu_power);
+ pr_cont(" (cpu_power = %d)", group->cpu_power);
}

group = group->next;
} while (group != sd->groups);
- printk(KERN_CONT "\n");
+ pr_cont("\n");

if (!cpumask_equal(sched_domain_span(sd), groupmask))
- printk(KERN_ERR "ERROR: groups don't span domain->span\n");
+ pr_err("ERROR: groups don't span domain->span\n");

if (sd->parent &&
!cpumask_subset(groupmask, sched_domain_span(sd->parent)))
- printk(KERN_ERR "ERROR: parent span is not a superset "
- "of domain->span\n");
+ pr_err("ERROR: parent span is not a superset of domain->span\n");
return 0;
}

@@ -8427,8 +8443,7 @@ static int build_numa_sched_groups(struct s_data *d,
sg = kmalloc_node(sizeof(struct sched_group) + cpumask_size(),
GFP_KERNEL, num);
if (!sg) {
- printk(KERN_WARNING "Can not alloc domain group for node %d\n",
- num);
+ pr_warning("Can not alloc domain group for node %d\n", num);
return -ENOMEM;
}
d->sched_group_nodes[num] = sg;
@@ -8457,8 +8472,8 @@ static int build_numa_sched_groups(struct s_data *d,
sg = kmalloc_node(sizeof(struct sched_group) + cpumask_size(),
GFP_KERNEL, num);
if (!sg) {
- printk(KERN_WARNING
- "Can not alloc domain group for node %d\n", j);
+ pr_warning("Can not alloc domain group for node %d\n",
+ j);
return -ENOMEM;
}
sg->cpu_power = 0;
@@ -8686,7 +8701,7 @@ static enum s_alloc __visit_domain_allocation_hell(struct s_data *d,
d->sched_group_nodes = kcalloc(nr_node_ids,
sizeof(struct sched_group *), GFP_KERNEL);
if (!d->sched_group_nodes) {
- printk(KERN_WARNING "Can not alloc sched group node list\n");
+ pr_warning("Can not alloc sched group node list\n");
return sa_notcovered;
}
sched_group_nodes_bycpu[cpumask_first(cpu_map)] = d->sched_group_nodes;
@@ -8703,7 +8718,7 @@ static enum s_alloc __visit_domain_allocation_hell(struct s_data *d,
return sa_send_covered;
d->rd = alloc_rootdomain();
if (!d->rd) {
- printk(KERN_WARNING "Cannot alloc root domain\n");
+ pr_warning("Cannot alloc root domain\n");
return sa_tmpmask;
}
return sa_rootdomain;
@@ -9668,7 +9683,7 @@ void __init sched_init(void)
#ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
static inline int preempt_count_equals(int preempt_offset)
{
- int nested = preempt_count() & ~PREEMPT_ACTIVE;
+ int nested = (preempt_count() & ~PREEMPT_ACTIVE) + rcu_preempt_depth();

return (nested == PREEMPT_INATOMIC_BASE + preempt_offset);
}
@@ -9685,13 +9700,11 @@ void __might_sleep(char *file, int line, int preempt_offset)
return;
prev_jiffy = jiffies;

- printk(KERN_ERR
- "BUG: sleeping function called from invalid context at %s:%d\n",
- file, line);
- printk(KERN_ERR
- "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
- in_atomic(), irqs_disabled(),
- current->pid, current->comm);
+ pr_err("BUG: sleeping function called from invalid context at %s:%d\n",
+ file, line);
+ pr_err("in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
+ in_atomic(), irqs_disabled(),
+ current->pid, current->comm);

debug_show_held_locks(current);
if (irqs_disabled())
@@ -10083,7 +10096,7 @@ void sched_move_task(struct task_struct *tsk)

#ifdef CONFIG_FAIR_GROUP_SCHED
if (tsk->sched_class->moved_group)
- tsk->sched_class->moved_group(tsk);
+ tsk->sched_class->moved_group(tsk, on_rq);
#endif

if (unlikely(running))
diff --git a/kernel/sched_clock.c b/kernel/sched_clock.c
index 479ce56..5b49613 100644
--- a/kernel/sched_clock.c
+++ b/kernel/sched_clock.c
@@ -236,6 +236,18 @@ void sched_clock_idle_wakeup_event(u64 delta_ns)
}
EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event);

+unsigned long long cpu_clock(int cpu)
+{
+ unsigned long long clock;
+ unsigned long flags;
+
+ local_irq_save(flags);
+ clock = sched_clock_cpu(cpu);
+ local_irq_restore(flags);
+
+ return clock;
+}
+
#else /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */

void sched_clock_init(void)
@@ -251,17 +263,12 @@ u64 sched_clock_cpu(int cpu)
return sched_clock();
}

-#endif /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */

unsigned long long cpu_clock(int cpu)
{
- unsigned long long clock;
- unsigned long flags;
+ return sched_clock_cpu(cpu);
+}

- local_irq_save(flags);
- clock = sched_clock_cpu(cpu);
- local_irq_restore(flags);
+#endif /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */

- return clock;
-}
EXPORT_SYMBOL_GPL(cpu_clock);
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 5bedf6e..42ac3c9 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -510,6 +510,7 @@ __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
curr->sum_exec_runtime += delta_exec;
schedstat_add(cfs_rq, exec_clock, delta_exec);
delta_exec_weighted = calc_delta_fair(delta_exec, curr);
+
curr->vruntime += delta_exec_weighted;
update_min_vruntime(cfs_rq);
}
@@ -765,16 +766,26 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
se->vruntime = vruntime;
}

+#define ENQUEUE_WAKEUP 1
+#define ENQUEUE_MIGRATE 2
+
static void
-enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
+enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
{
/*
+ * Update the normalized vruntime before updating min_vruntime
+ * through callig update_curr().
+ */
+ if (!(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_MIGRATE))
+ se->vruntime += cfs_rq->min_vruntime;
+
+ /*
* Update run-time statistics of the 'current'.
*/
update_curr(cfs_rq);
account_entity_enqueue(cfs_rq, se);

- if (wakeup) {
+ if (flags & ENQUEUE_WAKEUP) {
place_entity(cfs_rq, se, 0);
enqueue_sleeper(cfs_rq, se);
}
@@ -828,6 +839,14 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
__dequeue_entity(cfs_rq, se);
account_entity_dequeue(cfs_rq, se);
update_min_vruntime(cfs_rq);
+
+ /*
+ * Normalize the entity after updating the min_vruntime because the
+ * update can refer to the ->curr item and we need to reflect this
+ * movement in our normalized position.
+ */
+ if (!sleep)
+ se->vruntime -= cfs_rq->min_vruntime;
}

/*
@@ -1038,13 +1057,19 @@ static void enqueue_task_fair(struct rq *rq, struct task_struct *p, int wakeup)
{
struct cfs_rq *cfs_rq;
struct sched_entity *se = &p->se;
+ int flags = 0;
+
+ if (wakeup)
+ flags |= ENQUEUE_WAKEUP;
+ if (p->state == TASK_WAKING)
+ flags |= ENQUEUE_MIGRATE;

for_each_sched_entity(se) {
if (se->on_rq)
break;
cfs_rq = cfs_rq_of(se);
- enqueue_entity(cfs_rq, se, wakeup);
- wakeup = 1;
+ enqueue_entity(cfs_rq, se, flags);
+ flags = ENQUEUE_WAKEUP;
}

hrtick_update(rq);
@@ -1120,6 +1145,14 @@ static void yield_task_fair(struct rq *rq)

#ifdef CONFIG_SMP

+static void task_waking_fair(struct rq *rq, struct task_struct *p)
+{
+ struct sched_entity *se = &p->se;
+ struct cfs_rq *cfs_rq = cfs_rq_of(se);
+
+ se->vruntime -= cfs_rq->min_vruntime;
+}
+
#ifdef CONFIG_FAIR_GROUP_SCHED
/*
* effective_load() calculates the load change as seen from the root_task_group
@@ -1429,6 +1462,9 @@ static int select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flag
}

for_each_domain(cpu, tmp) {
+ if (!(tmp->flags & SD_LOAD_BALANCE))
+ continue;
+
/*
* If power savings logic is enabled for a domain, see if we
* are not overloaded, if so, don't balance wider.
@@ -1975,6 +2011,8 @@ static void task_fork_fair(struct task_struct *p)
resched_task(rq->curr);
}

+ se->vruntime -= cfs_rq->min_vruntime;
+
raw_spin_unlock_irqrestore(&rq->lock, flags);
}

@@ -2028,12 +2066,13 @@ static void set_curr_task_fair(struct rq *rq)
}

#ifdef CONFIG_FAIR_GROUP_SCHED
-static void moved_group_fair(struct task_struct *p)
+static void moved_group_fair(struct task_struct *p, int on_rq)
{
struct cfs_rq *cfs_rq = task_cfs_rq(p);

update_curr(cfs_rq);
- place_entity(cfs_rq, &p->se, 1);
+ if (!on_rq)
+ place_entity(cfs_rq, &p->se, 1);
}
#endif

@@ -2073,6 +2112,8 @@ static const struct sched_class fair_sched_class = {
.move_one_task = move_one_task_fair,
.rq_online = rq_online_fair,
.rq_offline = rq_offline_fair,
+
+ .task_waking = task_waking_fair,
#endif

.set_curr_task = set_curr_task_fair,
diff --git a/kernel/sched_idletask.c b/kernel/sched_idletask.c
index 5f93b57..21b969a 100644
--- a/kernel/sched_idletask.c
+++ b/kernel/sched_idletask.c
@@ -35,7 +35,7 @@ static void
dequeue_task_idle(struct rq *rq, struct task_struct *p, int sleep)
{
raw_spin_unlock_irq(&rq->lock);
- printk(KERN_ERR "bad: scheduling from the idle thread!\n");
+ pr_err("bad: scheduling from the idle thread!\n");
dump_stack();
raw_spin_lock_irq(&rq->lock);
}
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index d2ea282..f48328a 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -1472,7 +1472,7 @@ static void post_schedule_rt(struct rq *rq)
* If we are not running and we are not going to reschedule soon, we should
* try to push tasks away now
*/
-static void task_wake_up_rt(struct rq *rq, struct task_struct *p)
+static void task_woken_rt(struct rq *rq, struct task_struct *p)
{
if (!task_running(rq, p) &&
!test_tsk_need_resched(rq->curr) &&
@@ -1753,7 +1753,7 @@ static const struct sched_class rt_sched_class = {
.rq_offline = rq_offline_rt,
.pre_schedule = pre_schedule_rt,
.post_schedule = post_schedule_rt,
- .task_wake_up = task_wake_up_rt,
+ .task_woken = task_woken_rt,
.switched_from = switched_from_rt,
#endif