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Merge branch 'sched/migrate-disable'

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This commit is contained in:
Peter Zijlstra 2020-11-10 18:39:04 +01:00
commit 12fa97c64d
19 changed files with 1056 additions and 245 deletions
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4
fs/proc/array.c
View File

@ -382,9 +382,9 @@ static inline void task_context_switch_counts(struct seq_file *m,
static void task_cpus_allowed(struct seq_file *m, struct task_struct *task)
{
seq_printf(m, "Cpus_allowed:\t%*pb\n",
cpumask_pr_args(task->cpus_ptr));
cpumask_pr_args(&task->cpus_mask));
seq_printf(m, "Cpus_allowed_list:\t%*pbl\n",
cpumask_pr_args(task->cpus_ptr));
cpumask_pr_args(&task->cpus_mask));
}
static inline void task_core_dumping(struct seq_file *m, struct mm_struct *mm)

1
include/linux/cpuhotplug.h
View File

@ -152,6 +152,7 @@ enum cpuhp_state {
CPUHP_AP_ONLINE,
CPUHP_TEARDOWN_CPU,
CPUHP_AP_ONLINE_IDLE,
CPUHP_AP_SCHED_WAIT_EMPTY,
CPUHP_AP_SMPBOOT_THREADS,
CPUHP_AP_X86_VDSO_VMA_ONLINE,
CPUHP_AP_IRQ_AFFINITY_ONLINE,

6
include/linux/cpumask.h
View File

@ -199,6 +199,11 @@ static inline int cpumask_any_and_distribute(const struct cpumask *src1p,
return cpumask_next_and(-1, src1p, src2p);
}
static inline int cpumask_any_distribute(const struct cpumask *srcp)
{
return cpumask_first(srcp);
}
#define for_each_cpu(cpu, mask) \
for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask)
#define for_each_cpu_not(cpu, mask) \
@ -252,6 +257,7 @@ int cpumask_any_but(const struct cpumask *mask, unsigned int cpu);
unsigned int cpumask_local_spread(unsigned int i, int node);
int cpumask_any_and_distribute(const struct cpumask *src1p,
const struct cpumask *src2p);
int cpumask_any_distribute(const struct cpumask *srcp);
/**
* for_each_cpu - iterate over every cpu in a mask

69
include/linux/preempt.h
View File

@ -322,6 +322,73 @@ static inline void preempt_notifier_init(struct preempt_notifier *notifier,
#endif
#if defined(CONFIG_SMP) && defined(CONFIG_PREEMPT_RT)
/*
* Migrate-Disable and why it is undesired.
*
* When a preempted task becomes elegible to run under the ideal model (IOW it
* becomes one of the M highest priority tasks), it might still have to wait
* for the preemptee's migrate_disable() section to complete. Thereby suffering
* a reduction in bandwidth in the exact duration of the migrate_disable()
* section.
*
* Per this argument, the change from preempt_disable() to migrate_disable()
* gets us:
*
* - a higher priority tasks gains reduced wake-up latency; with preempt_disable()
* it would have had to wait for the lower priority task.
*
* - a lower priority tasks; which under preempt_disable() could've instantly
* migrated away when another CPU becomes available, is now constrained
* by the ability to push the higher priority task away, which might itself be
* in a migrate_disable() section, reducing it's available bandwidth.
*
* IOW it trades latency / moves the interference term, but it stays in the
* system, and as long as it remains unbounded, the system is not fully
* deterministic.
*
*
* The reason we have it anyway.
*
* PREEMPT_RT breaks a number of assumptions traditionally held. By forcing a
* number of primitives into becoming preemptible, they would also allow
* migration. This turns out to break a bunch of per-cpu usage. To this end,
* all these primitives employ migirate_disable() to restore this implicit
* assumption.
*
* This is a 'temporary' work-around at best. The correct solution is getting
* rid of the above assumptions and reworking the code to employ explicit
* per-cpu locking or short preempt-disable regions.
*
* The end goal must be to get rid of migrate_disable(), alternatively we need
* a schedulability theory that does not depend on abritrary migration.
*
*
* Notes on the implementation.
*
* The implementation is particularly tricky since existing code patterns
* dictate neither migrate_disable() nor migrate_enable() is allowed to block.
* This means that it cannot use cpus_read_lock() to serialize against hotplug,
* nor can it easily migrate itself into a pending affinity mask change on
* migrate_enable().
*
*
* Note: even non-work-conserving schedulers like semi-partitioned depends on
* migration, so migrate_disable() is not only a problem for
* work-conserving schedulers.
*
*/
extern void migrate_disable(void);
extern void migrate_enable(void);
#elif defined(CONFIG_PREEMPT_RT)
static inline void migrate_disable(void) { }
static inline void migrate_enable(void) { }
#else /* !CONFIG_PREEMPT_RT */
/**
* migrate_disable - Prevent migration of the current task
*
@ -352,4 +419,6 @@ static __always_inline void migrate_enable(void)
preempt_enable();
}
#endif /* CONFIG_SMP && CONFIG_PREEMPT_RT */
#endif /* __LINUX_PREEMPT_H */

5
include/linux/sched.h
View File

@ -714,6 +714,11 @@ struct task_struct {
int nr_cpus_allowed;
const cpumask_t *cpus_ptr;
cpumask_t cpus_mask;
void *migration_pending;
#if defined(CONFIG_SMP) && defined(CONFIG_PREEMPT_RT)
unsigned short migration_disabled;
#endif
unsigned short migration_flags;
#ifdef CONFIG_PREEMPT_RCU
int rcu_read_lock_nesting;

2
include/linux/sched/hotplug.h
View File

@ -11,8 +11,10 @@ extern int sched_cpu_activate(unsigned int cpu);
extern int sched_cpu_deactivate(unsigned int cpu);
#ifdef CONFIG_HOTPLUG_CPU
extern int sched_cpu_wait_empty(unsigned int cpu);
extern int sched_cpu_dying(unsigned int cpu);
#else
# define sched_cpu_wait_empty NULL
# define sched_cpu_dying NULL
#endif

5
include/linux/stop_machine.h
View File

@ -24,6 +24,7 @@ typedef int (*cpu_stop_fn_t)(void *arg);
struct cpu_stop_work {
struct list_head list; /* cpu_stopper->works */
cpu_stop_fn_t fn;
unsigned long caller;
void *arg;
struct cpu_stop_done *done;
};
@ -36,6 +37,8 @@ void stop_machine_park(int cpu);
void stop_machine_unpark(int cpu);
void stop_machine_yield(const struct cpumask *cpumask);
extern void print_stop_info(const char *log_lvl, struct task_struct *task);
#else /* CONFIG_SMP */
#include <linux/workqueue.h>
@ -80,6 +83,8 @@ static inline bool stop_one_cpu_nowait(unsigned int cpu,
return false;
}
static inline void print_stop_info(const char *log_lvl, struct task_struct *task) { }
#endif /* CONFIG_SMP */
/*

9
kernel/cpu.c
View File

@ -1602,7 +1602,7 @@ static struct cpuhp_step cpuhp_hp_states[] = {
.name = "ap:online",
},
/*
* Handled on controll processor until the plugged processor manages
* Handled on control processor until the plugged processor manages
* this itself.
*/
[CPUHP_TEARDOWN_CPU] = {
@ -1611,6 +1611,13 @@ static struct cpuhp_step cpuhp_hp_states[] = {
.teardown.single = takedown_cpu,
.cant_stop = true,
},
[CPUHP_AP_SCHED_WAIT_EMPTY] = {
.name = "sched:waitempty",
.startup.single = NULL,
.teardown.single = sched_cpu_wait_empty,
},
/* Handle smpboot threads park/unpark */
[CPUHP_AP_SMPBOOT_THREADS] = {
.name = "smpboot/threads:online",

956
kernel/sched/core.c
View File

File diff suppressed because it is too large Load Diff

4
kernel/sched/cpudeadline.c
View File

@ -120,7 +120,7 @@ int cpudl_find(struct cpudl *cp, struct task_struct *p,
const struct sched_dl_entity *dl_se = &p->dl;
if (later_mask &&
cpumask_and(later_mask, cp->free_cpus, p->cpus_ptr)) {
cpumask_and(later_mask, cp->free_cpus, &p->cpus_mask)) {
unsigned long cap, max_cap = 0;
int cpu, max_cpu = -1;
@ -151,7 +151,7 @@ int cpudl_find(struct cpudl *cp, struct task_struct *p,
WARN_ON(best_cpu != -1 && !cpu_present(best_cpu));
if (cpumask_test_cpu(best_cpu, p->cpus_ptr) &&
if (cpumask_test_cpu(best_cpu, &p->cpus_mask) &&
dl_time_before(dl_se->deadline, cp->elements[0].dl)) {
if (later_mask)
cpumask_set_cpu(best_cpu, later_mask);

4
kernel/sched/cpupri.c
View File

@ -97,11 +97,11 @@ static inline int __cpupri_find(struct cpupri *cp, struct task_struct *p,
if (skip)
return 0;
if (cpumask_any_and(p->cpus_ptr, vec->mask) >= nr_cpu_ids)
if (cpumask_any_and(&p->cpus_mask, vec->mask) >= nr_cpu_ids)
return 0;
if (lowest_mask) {
cpumask_and(lowest_mask, p->cpus_ptr, vec->mask);
cpumask_and(lowest_mask, &p->cpus_mask, vec->mask);
/*
* We have to ensure that we have at least one bit

46
kernel/sched/deadline.c
View File

@ -559,7 +559,7 @@ static int push_dl_task(struct rq *rq);
static inline bool need_pull_dl_task(struct rq *rq, struct task_struct *prev)
{
return dl_task(prev);
return rq->online && dl_task(prev);
}
static DEFINE_PER_CPU(struct callback_head, dl_push_head);
@ -1931,7 +1931,7 @@ static void task_fork_dl(struct task_struct *p)
static int pick_dl_task(struct rq *rq, struct task_struct *p, int cpu)
{
if (!task_running(rq, p) &&
cpumask_test_cpu(cpu, p->cpus_ptr))
cpumask_test_cpu(cpu, &p->cpus_mask))
return 1;
return 0;
}
@ -2021,8 +2021,8 @@ static int find_later_rq(struct task_struct *task)
return this_cpu;
}
best_cpu = cpumask_first_and(later_mask,
sched_domain_span(sd));
best_cpu = cpumask_any_and_distribute(later_mask,
sched_domain_span(sd));
/*
* Last chance: if a CPU being in both later_mask
* and current sd span is valid, that becomes our
@ -2044,7 +2044,7 @@ static int find_later_rq(struct task_struct *task)
if (this_cpu != -1)
return this_cpu;
cpu = cpumask_any(later_mask);
cpu = cpumask_any_distribute(later_mask);
if (cpu < nr_cpu_ids)
return cpu;
@ -2081,7 +2081,7 @@ static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq)
/* Retry if something changed. */
if (double_lock_balance(rq, later_rq)) {
if (unlikely(task_rq(task) != rq ||
!cpumask_test_cpu(later_rq->cpu, task->cpus_ptr) ||
!cpumask_test_cpu(later_rq->cpu, &task->cpus_mask) ||
task_running(rq, task) ||
!dl_task(task) ||
!task_on_rq_queued(task))) {
@ -2148,6 +2148,9 @@ static int push_dl_task(struct rq *rq)
return 0;
retry:
if (is_migration_disabled(next_task))
return 0;
if (WARN_ON(next_task == rq->curr))
return 0;
@ -2225,7 +2228,7 @@ static void push_dl_tasks(struct rq *rq)
static void pull_dl_task(struct rq *this_rq)
{
int this_cpu = this_rq->cpu, cpu;
struct task_struct *p;
struct task_struct *p, *push_task;
bool resched = false;
struct rq *src_rq;
u64 dmin = LONG_MAX;
@ -2255,6 +2258,7 @@ static void pull_dl_task(struct rq *this_rq)
continue;
/* Might drop this_rq->lock */
push_task = NULL;
double_lock_balance(this_rq, src_rq);
/*
@ -2286,17 +2290,27 @@ static void pull_dl_task(struct rq *this_rq)
src_rq->curr->dl.deadline))
goto skip;
resched = true;
deactivate_task(src_rq, p, 0);
set_task_cpu(p, this_cpu);
activate_task(this_rq, p, 0);
dmin = p->dl.deadline;
if (is_migration_disabled(p)) {
push_task = get_push_task(src_rq);
} else {
deactivate_task(src_rq, p, 0);
set_task_cpu(p, this_cpu);
activate_task(this_rq, p, 0);
dmin = p->dl.deadline;
resched = true;
}
/* Is there any other task even earlier? */
}
skip:
double_unlock_balance(this_rq, src_rq);
if (push_task) {
raw_spin_unlock(&this_rq->lock);
stop_one_cpu_nowait(src_rq->cpu, push_cpu_stop,
push_task, &src_rq->push_work);
raw_spin_lock(&this_rq->lock);
}
}
if (resched)
@ -2320,7 +2334,8 @@ static void task_woken_dl(struct rq *rq, struct task_struct *p)
}
static void set_cpus_allowed_dl(struct task_struct *p,
const struct cpumask *new_mask)
const struct cpumask *new_mask,
u32 flags)
{
struct root_domain *src_rd;
struct rq *rq;
@ -2349,7 +2364,7 @@ static void set_cpus_allowed_dl(struct task_struct *p,
raw_spin_unlock(&src_dl_b->lock);
}
set_cpus_allowed_common(p, new_mask);
set_cpus_allowed_common(p, new_mask, flags);
}
/* Assumes rq->lock is held */
@ -2542,6 +2557,7 @@ DEFINE_SCHED_CLASS(dl) = {
.rq_online = rq_online_dl,
.rq_offline = rq_offline_dl,
.task_woken = task_woken_dl,
.find_lock_rq = find_lock_later_rq,
#endif
.task_tick = task_tick_dl,

75
kernel/sched/rt.c
View File

@ -265,7 +265,7 @@ static void pull_rt_task(struct rq *this_rq);
static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev)
{
/* Try to pull RT tasks here if we lower this rq's prio */
return rq->rt.highest_prio.curr > prev->prio;
return rq->online && rq->rt.highest_prio.curr > prev->prio;
}
static inline int rt_overloaded(struct rq *rq)
@ -1660,7 +1660,7 @@ static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
{
if (!task_running(rq, p) &&
cpumask_test_cpu(cpu, p->cpus_ptr))
cpumask_test_cpu(cpu, &p->cpus_mask))
return 1;
return 0;
@ -1754,8 +1754,8 @@ static int find_lowest_rq(struct task_struct *task)
return this_cpu;
}
best_cpu = cpumask_first_and(lowest_mask,
sched_domain_span(sd));
best_cpu = cpumask_any_and_distribute(lowest_mask,
sched_domain_span(sd));
if (best_cpu < nr_cpu_ids) {
rcu_read_unlock();
return best_cpu;
@ -1772,7 +1772,7 @@ static int find_lowest_rq(struct task_struct *task)
if (this_cpu != -1)
return this_cpu;
cpu = cpumask_any(lowest_mask);
cpu = cpumask_any_distribute(lowest_mask);
if (cpu < nr_cpu_ids)
return cpu;
@ -1813,7 +1813,7 @@ static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
* Also make sure that it wasn't scheduled on its rq.
*/
if (unlikely(task_rq(task) != rq ||
!cpumask_test_cpu(lowest_rq->cpu, task->cpus_ptr) ||
!cpumask_test_cpu(lowest_rq->cpu, &task->cpus_mask) ||
task_running(rq, task) ||
!rt_task(task) ||
!task_on_rq_queued(task))) {
@ -1861,7 +1861,7 @@ static struct task_struct *pick_next_pushable_task(struct rq *rq)
* running task can migrate over to a CPU that is running a task
* of lesser priority.
*/
static int push_rt_task(struct rq *rq)
static int push_rt_task(struct rq *rq, bool pull)
{
struct task_struct *next_task;
struct rq *lowest_rq;
@ -1875,6 +1875,34 @@ static int push_rt_task(struct rq *rq)
return 0;
retry:
if (is_migration_disabled(next_task)) {
struct task_struct *push_task = NULL;
int cpu;
if (!pull || rq->push_busy)
return 0;
cpu = find_lowest_rq(rq->curr);
if (cpu == -1 || cpu == rq->cpu)
return 0;
/*
* Given we found a CPU with lower priority than @next_task,
* therefore it should be running. However we cannot migrate it
* to this other CPU, instead attempt to push the current
* running task on this CPU away.
*/
push_task = get_push_task(rq);
if (push_task) {
raw_spin_unlock(&rq->lock);
stop_one_cpu_nowait(rq->cpu, push_cpu_stop,
push_task, &rq->push_work);
raw_spin_lock(&rq->lock);
}
return 0;
}
if (WARN_ON(next_task == rq->curr))
return 0;
@ -1929,12 +1957,10 @@ retry:
deactivate_task(rq, next_task, 0);
set_task_cpu(next_task, lowest_rq->cpu);
activate_task(lowest_rq, next_task, 0);
resched_curr(lowest_rq);
ret = 1;
resched_curr(lowest_rq);
double_unlock_balance(rq, lowest_rq);
out:
put_task_struct(next_task);
@ -1944,7 +1970,7 @@ out:
static void push_rt_tasks(struct rq *rq)
{
/* push_rt_task will return true if it moved an RT */
while (push_rt_task(rq))
while (push_rt_task(rq, false))
;
}
@ -2097,7 +2123,8 @@ void rto_push_irq_work_func(struct irq_work *work)
*/
if (has_pushable_tasks(rq)) {
raw_spin_lock(&rq->lock);
push_rt_tasks(rq);
while (push_rt_task(rq, true))
;
raw_spin_unlock(&rq->lock);
}
@ -2122,7 +2149,7 @@ static void pull_rt_task(struct rq *this_rq)
{
int this_cpu = this_rq->cpu, cpu;
bool resched = false;
struct task_struct *p;
struct task_struct *p, *push_task;
struct rq *src_rq;
int rt_overload_count = rt_overloaded(this_rq);
@ -2169,6 +2196,7 @@ static void pull_rt_task(struct rq *this_rq)
* double_lock_balance, and another CPU could
* alter this_rq
*/
push_task = NULL;
double_lock_balance(this_rq, src_rq);
/*
@ -2196,11 +2224,14 @@ static void pull_rt_task(struct rq *this_rq)
if (p->prio < src_rq->curr->prio)
goto skip;
resched = true;
deactivate_task(src_rq, p, 0);
set_task_cpu(p, this_cpu);
activate_task(this_rq, p, 0);
if (is_migration_disabled(p)) {
push_task = get_push_task(src_rq);
} else {
deactivate_task(src_rq, p, 0);
set_task_cpu(p, this_cpu);
activate_task(this_rq, p, 0);
resched = true;
}
/*
* We continue with the search, just in
* case there's an even higher prio task
@ -2210,6 +2241,13 @@ static void pull_rt_task(struct rq *this_rq)
}
skip:
double_unlock_balance(this_rq, src_rq);
if (push_task) {
raw_spin_unlock(&this_rq->lock);
stop_one_cpu_nowait(src_rq->cpu, push_cpu_stop,
push_task, &src_rq->push_work);
raw_spin_lock(&this_rq->lock);
}
}
if (resched)
@ -2451,6 +2489,7 @@ DEFINE_SCHED_CLASS(rt) = {
.rq_offline = rq_offline_rt,
.task_woken = task_woken_rt,
.switched_from = switched_from_rt,
.find_lock_rq = find_lock_lowest_rq,
#endif
.task_tick = task_tick_rt,

59
kernel/sched/sched.h
View File

@ -975,6 +975,7 @@ struct rq {
unsigned long cpu_capacity_orig;
struct callback_head *balance_callback;
unsigned char balance_flags;
unsigned char nohz_idle_balance;
unsigned char idle_balance;
@ -1005,6 +1006,10 @@ struct rq {
/* This is used to determine avg_idle's max value */
u64 max_idle_balance_cost;
#ifdef CONFIG_HOTPLUG_CPU
struct rcuwait hotplug_wait;
#endif
#endif /* CONFIG_SMP */
#ifdef CONFIG_IRQ_TIME_ACCOUNTING
@ -1050,6 +1055,12 @@ struct rq {
/* Must be inspected within a rcu lock section */
struct cpuidle_state *idle_state;
#endif
#if defined(CONFIG_PREEMPT_RT) && defined(CONFIG_SMP)
unsigned int nr_pinned;
#endif
unsigned int push_busy;
struct cpu_stop_work push_work;
};
#ifdef CONFIG_FAIR_GROUP_SCHED
@ -1077,6 +1088,16 @@ static inline int cpu_of(struct rq *rq)
#endif
}
#define MDF_PUSH 0x01
static inline bool is_migration_disabled(struct task_struct *p)
{
#if defined(CONFIG_SMP) && defined(CONFIG_PREEMPT_RT)
return p->migration_disabled;
#else
return false;
#endif
}
#ifdef CONFIG_SCHED_SMT
extern void __update_idle_core(struct rq *rq);
@ -1223,6 +1244,9 @@ static inline void rq_pin_lock(struct rq *rq, struct rq_flags *rf)
rq->clock_update_flags &= (RQCF_REQ_SKIP|RQCF_ACT_SKIP);
rf->clock_update_flags = 0;
#endif
#ifdef CONFIG_SMP
SCHED_WARN_ON(rq->balance_callback);
#endif
}
static inline void rq_unpin_lock(struct rq *rq, struct rq_flags *rf)
@ -1384,6 +1408,9 @@ init_numa_balancing(unsigned long clone_flags, struct task_struct *p)
#ifdef CONFIG_SMP
#define BALANCE_WORK 0x01
#define BALANCE_PUSH 0x02
static inline void
queue_balance_callback(struct rq *rq,
struct callback_head *head,
@ -1391,12 +1418,13 @@ queue_balance_callback(struct rq *rq,
{
lockdep_assert_held(&rq->lock);
if (unlikely(head->next))
if (unlikely(head->next || (rq->balance_flags & BALANCE_PUSH)))
return;
head->func = (void (*)(struct callback_head *))func;
head->next = rq->balance_callback;
rq->balance_callback = head;
rq->balance_flags |= BALANCE_WORK;
}
#define rcu_dereference_check_sched_domain(p) \
@ -1804,10 +1832,13 @@ struct sched_class {
void (*task_woken)(struct rq *this_rq, struct task_struct *task);
void (*set_cpus_allowed)(struct task_struct *p,
const struct cpumask *newmask);
const struct cpumask *newmask,
u32 flags);
void (*rq_online)(struct rq *rq);
void (*rq_offline)(struct rq *rq);
struct rq *(*find_lock_rq)(struct task_struct *p, struct rq *rq);
#endif
void (*task_tick)(struct rq *rq, struct task_struct *p, int queued);
@ -1905,13 +1936,35 @@ static inline bool sched_fair_runnable(struct rq *rq)
extern struct task_struct *pick_next_task_fair(struct rq *rq, struct task_struct *prev, struct rq_flags *rf);
extern struct task_struct *pick_next_task_idle(struct rq *rq);
#define SCA_CHECK 0x01
#define SCA_MIGRATE_DISABLE 0x02
#define SCA_MIGRATE_ENABLE 0x04
#ifdef CONFIG_SMP
extern void update_group_capacity(struct sched_domain *sd, int cpu);
extern void trigger_load_balance(struct rq *rq);
extern void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask);
extern void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask, u32 flags);
static inline struct task_struct *get_push_task(struct rq *rq)
{
struct task_struct *p = rq->curr;
lockdep_assert_held(&rq->lock);
if (rq->push_busy)
return NULL;
if (p->nr_cpus_allowed == 1)
return NULL;
rq->push_busy = true;
return get_task_struct(p);
}
extern int push_cpu_stop(void *arg);
#endif

27
kernel/stop_machine.c
View File

@ -42,11 +42,27 @@ struct cpu_stopper {
struct list_head works; /* list of pending works */
struct cpu_stop_work stop_work; /* for stop_cpus */
unsigned long caller;
cpu_stop_fn_t fn;
};
static DEFINE_PER_CPU(struct cpu_stopper, cpu_stopper);
static bool stop_machine_initialized = false;
void print_stop_info(const char *log_lvl, struct task_struct *task)
{
/*
* If @task is a stopper task, it cannot migrate and task_cpu() is
* stable.
*/
struct cpu_stopper *stopper = per_cpu_ptr(&cpu_stopper, task_cpu(task));
if (task != stopper->thread)
return;
printk("%sStopper: %pS <- %pS\n", log_lvl, stopper->fn, (void *)stopper->caller);
}
/* static data for stop_cpus */
static DEFINE_MUTEX(stop_cpus_mutex);
static bool stop_cpus_in_progress;
@ -123,7 +139,7 @@ static bool cpu_stop_queue_work(unsigned int cpu, struct cpu_stop_work *work)
int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
{
struct cpu_stop_done done;
struct cpu_stop_work work = { .fn = fn, .arg = arg, .done = &done };
struct cpu_stop_work work = { .fn = fn, .arg = arg, .done = &done, .caller = _RET_IP_ };
cpu_stop_init_done(&done, 1);
if (!cpu_stop_queue_work(cpu, &work))
@ -331,7 +347,8 @@ int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *
work1 = work2 = (struct cpu_stop_work){
.fn = multi_cpu_stop,
.arg = &msdata,
.done = &done
.done = &done,
.caller = _RET_IP_,
};
cpu_stop_init_done(&done, 2);
@ -367,7 +384,7 @@ int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *
bool stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg,
struct cpu_stop_work *work_buf)
{
*work_buf = (struct cpu_stop_work){ .fn = fn, .arg = arg, };
*work_buf = (struct cpu_stop_work){ .fn = fn, .arg = arg, .caller = _RET_IP_, };
return cpu_stop_queue_work(cpu, work_buf);
}
@ -487,6 +504,8 @@ repeat:
int ret;
/* cpu stop callbacks must not sleep, make in_atomic() == T */
stopper->caller = work->caller;
stopper->fn = fn;
preempt_count_inc();
ret = fn(arg);
if (done) {
@ -495,6 +514,8 @@ repeat:
cpu_stop_signal_done(done);
}
preempt_count_dec();
stopper->fn = NULL;
stopper->caller = 0;
WARN_ONCE(preempt_count(),
"cpu_stop: %ps(%p) leaked preempt count\n", fn, arg);
goto repeat;

4
kernel/workqueue.c
View File

@ -4908,6 +4908,10 @@ static void unbind_workers(int cpu)
pool->flags |= POOL_DISASSOCIATED;
raw_spin_unlock_irq(&pool->lock);
for_each_pool_worker(worker, pool)
WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, cpu_active_mask) < 0);
mutex_unlock(&wq_pool_attach_mutex);
/*

18
lib/cpumask.c
View File

@ -267,3 +267,21 @@ int cpumask_any_and_distribute(const struct cpumask *src1p,
return next;
}
EXPORT_SYMBOL(cpumask_any_and_distribute);
int cpumask_any_distribute(const struct cpumask *srcp)
{
int next, prev;
/* NOTE: our first selection will skip 0. */
prev = __this_cpu_read(distribute_cpu_mask_prev);
next = cpumask_next(prev, srcp);
if (next >= nr_cpu_ids)
next = cpumask_first(srcp);
if (next < nr_cpu_ids)
__this_cpu_write(distribute_cpu_mask_prev, next);
return next;
}
EXPORT_SYMBOL(cpumask_any_distribute);

2
lib/dump_stack.c
View File

@ -12,6 +12,7 @@
#include <linux/atomic.h>
#include <linux/kexec.h>
#include <linux/utsname.h>
#include <linux/stop_machine.h>
static char dump_stack_arch_desc_str[128];
@ -57,6 +58,7 @@ void dump_stack_print_info(const char *log_lvl)
log_lvl, dump_stack_arch_desc_str);
print_worker_info(log_lvl, current);
print_stop_info(log_lvl, current);
}
/**

5
lib/smp_processor_id.c
View File

@ -26,6 +26,11 @@ unsigned int check_preemption_disabled(const char *what1, const char *what2)
if (current->nr_cpus_allowed == 1)
goto out;
#if defined(CONFIG_SMP) && defined(CONFIG_PREEMPT_RT)
if (current->migration_disabled)
goto out;
#endif
/*
* It is valid to assume CPU-locality during early bootup:
*/