sched: Fix balance vs hotplug race
Since (e761b77: cpu hotplug, sched: Introduce cpu_active_map and redo sched domain managment) we have cpu_active_mask which is suppose to rule scheduler migration and load-balancing, except it never (fully) did. The particular problem being solved here is a crash in try_to_wake_up() where select_task_rq() ends up selecting an offline cpu because select_task_rq_fair() trusts the sched_domain tree to reflect the current state of affairs, similarly select_task_rq_rt() trusts the root_domain. However, the sched_domains are updated from CPU_DEAD, which is after the cpu is taken offline and after stop_machine is done. Therefore it can race perfectly well with code assuming the domains are right. Cure this by building the domains from cpu_active_mask on CPU_DOWN_PREPARE. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra
Ingo Molnar
Родитель
e1b8090bdf
Коммит
6ad4c18884
|
|
@ -84,6 +84,7 @@ extern const struct cpumask *const cpu_active_mask;
|
|||
#define num_online_cpus() cpumask_weight(cpu_online_mask)
|
||||
#define num_possible_cpus() cpumask_weight(cpu_possible_mask)
|
||||
#define num_present_cpus() cpumask_weight(cpu_present_mask)
|
||||
#define num_active_cpus() cpumask_weight(cpu_active_mask)
|
||||
#define cpu_online(cpu) cpumask_test_cpu((cpu), cpu_online_mask)
|
||||
#define cpu_possible(cpu) cpumask_test_cpu((cpu), cpu_possible_mask)
|
||||
#define cpu_present(cpu) cpumask_test_cpu((cpu), cpu_present_mask)
|
||||
|
|
@ -92,6 +93,7 @@ extern const struct cpumask *const cpu_active_mask;
|
|||
#define num_online_cpus() 1
|
||||
#define num_possible_cpus() 1
|
||||
#define num_present_cpus() 1
|
||||
#define num_active_cpus() 1
|
||||
#define cpu_online(cpu) ((cpu) == 0)
|
||||
#define cpu_possible(cpu) ((cpu) == 0)
|
||||
#define cpu_present(cpu) ((cpu) == 0)
|
||||
|
|
|
|||
18
kernel/cpu.c
18
kernel/cpu.c
|
|
@ -212,6 +212,8 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
|
|||
err = __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE | mod,
|
||||
hcpu, -1, &nr_calls);
|
||||
if (err == NOTIFY_BAD) {
|
||||
set_cpu_active(cpu, true);
|
||||
|
||||
nr_calls--;
|
||||
__raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod,
|
||||
hcpu, nr_calls, NULL);
|
||||
|
|
@ -223,11 +225,11 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
|
|||
|
||||
/* Ensure that we are not runnable on dying cpu */
|
||||
cpumask_copy(old_allowed, ¤t->cpus_allowed);
|
||||
set_cpus_allowed_ptr(current,
|
||||
cpumask_of(cpumask_any_but(cpu_online_mask, cpu)));
|
||||
set_cpus_allowed_ptr(current, cpu_active_mask);
|
||||
|
||||
err = __stop_machine(take_cpu_down, &tcd_param, cpumask_of(cpu));
|
||||
if (err) {
|
||||
set_cpu_active(cpu, true);
|
||||
/* CPU didn't die: tell everyone. Can't complain. */
|
||||
if (raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod,
|
||||
hcpu) == NOTIFY_BAD)
|
||||
|
|
@ -292,9 +294,6 @@ int __ref cpu_down(unsigned int cpu)
|
|||
|
||||
err = _cpu_down(cpu, 0);
|
||||
|
||||
if (cpu_online(cpu))
|
||||
set_cpu_active(cpu, true);
|
||||
|
||||
out:
|
||||
cpu_maps_update_done();
|
||||
stop_machine_destroy();
|
||||
|
|
@ -387,6 +386,15 @@ int disable_nonboot_cpus(void)
|
|||
* 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)
|
||||
|
|
|
|||
|
|
@ -872,7 +872,7 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
|
|||
if (retval < 0)
|
||||
return retval;
|
||||
|
||||
if (!cpumask_subset(trialcs->cpus_allowed, cpu_online_mask))
|
||||
if (!cpumask_subset(trialcs->cpus_allowed, cpu_active_mask))
|
||||
return -EINVAL;
|
||||
}
|
||||
retval = validate_change(cs, trialcs);
|
||||
|
|
@ -2010,7 +2010,7 @@ static void scan_for_empty_cpusets(struct cpuset *root)
|
|||
}
|
||||
|
||||
/* Continue past cpusets with all cpus, mems online */
|
||||
if (cpumask_subset(cp->cpus_allowed, cpu_online_mask) &&
|
||||
if (cpumask_subset(cp->cpus_allowed, cpu_active_mask) &&
|
||||
nodes_subset(cp->mems_allowed, node_states[N_HIGH_MEMORY]))
|
||||
continue;
|
||||
|
||||
|
|
@ -2019,7 +2019,7 @@ static void scan_for_empty_cpusets(struct cpuset *root)
|
|||
/* Remove offline cpus and mems from this cpuset. */
|
||||
mutex_lock(&callback_mutex);
|
||||
cpumask_and(cp->cpus_allowed, cp->cpus_allowed,
|
||||
cpu_online_mask);
|
||||
cpu_active_mask);
|
||||
nodes_and(cp->mems_allowed, cp->mems_allowed,
|
||||
node_states[N_HIGH_MEMORY]);
|
||||
mutex_unlock(&callback_mutex);
|
||||
|
|
@ -2057,8 +2057,10 @@ static int cpuset_track_online_cpus(struct notifier_block *unused_nb,
|
|||
switch (phase) {
|
||||
case CPU_ONLINE:
|
||||
case CPU_ONLINE_FROZEN:
|
||||
case CPU_DEAD:
|
||||
case CPU_DEAD_FROZEN:
|
||||
case CPU_DOWN_PREPARE:
|
||||
case CPU_DOWN_PREPARE_FROZEN:
|
||||
case CPU_DOWN_FAILED:
|
||||
case CPU_DOWN_FAILED_FROZEN:
|
||||
break;
|
||||
|
||||
default:
|
||||
|
|
@ -2067,7 +2069,7 @@ static int cpuset_track_online_cpus(struct notifier_block *unused_nb,
|
|||
|
||||
cgroup_lock();
|
||||
mutex_lock(&callback_mutex);
|
||||
cpumask_copy(top_cpuset.cpus_allowed, cpu_online_mask);
|
||||
cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask);
|
||||
mutex_unlock(&callback_mutex);
|
||||
scan_for_empty_cpusets(&top_cpuset);
|
||||
ndoms = generate_sched_domains(&doms, &attr);
|
||||
|
|
@ -2114,7 +2116,7 @@ static int cpuset_track_online_nodes(struct notifier_block *self,
|
|||
|
||||
void __init cpuset_init_smp(void)
|
||||
{
|
||||
cpumask_copy(top_cpuset.cpus_allowed, cpu_online_mask);
|
||||
cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask);
|
||||
top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
|
||||
|
||||
hotcpu_notifier(cpuset_track_online_cpus, 0);
|
||||
|
|
|
|||
|
|
@ -4134,7 +4134,7 @@ static int load_balance(int this_cpu, struct rq *this_rq,
|
|||
unsigned long flags;
|
||||
struct cpumask *cpus = __get_cpu_var(load_balance_tmpmask);
|
||||
|
||||
cpumask_copy(cpus, cpu_online_mask);
|
||||
cpumask_copy(cpus, cpu_active_mask);
|
||||
|
||||
/*
|
||||
* When power savings policy is enabled for the parent domain, idle
|
||||
|
|
@ -4297,7 +4297,7 @@ load_balance_newidle(int this_cpu, struct rq *this_rq, struct sched_domain *sd)
|
|||
int all_pinned = 0;
|
||||
struct cpumask *cpus = __get_cpu_var(load_balance_tmpmask);
|
||||
|
||||
cpumask_copy(cpus, cpu_online_mask);
|
||||
cpumask_copy(cpus, cpu_active_mask);
|
||||
|
||||
/*
|
||||
* When power savings policy is enabled for the parent domain, idle
|
||||
|
|
@ -4694,7 +4694,7 @@ int select_nohz_load_balancer(int stop_tick)
|
|||
cpumask_set_cpu(cpu, nohz.cpu_mask);
|
||||
|
||||
/* time for ilb owner also to sleep */
|
||||
if (cpumask_weight(nohz.cpu_mask) == num_online_cpus()) {
|
||||
if (cpumask_weight(nohz.cpu_mask) == num_active_cpus()) {
|
||||
if (atomic_read(&nohz.load_balancer) == cpu)
|
||||
atomic_set(&nohz.load_balancer, -1);
|
||||
return 0;
|
||||
|
|
@ -7093,7 +7093,7 @@ int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
|
|||
int ret = 0;
|
||||
|
||||
rq = task_rq_lock(p, &flags);
|
||||
if (!cpumask_intersects(new_mask, cpu_online_mask)) {
|
||||
if (!cpumask_intersects(new_mask, cpu_active_mask)) {
|
||||
ret = -EINVAL;
|
||||
goto out;
|
||||
}
|
||||
|
|
@ -7115,7 +7115,7 @@ int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
|
|||
if (cpumask_test_cpu(task_cpu(p), new_mask))
|
||||
goto out;
|
||||
|
||||
if (migrate_task(p, cpumask_any_and(cpu_online_mask, new_mask), &req)) {
|
||||
if (migrate_task(p, cpumask_any_and(cpu_active_mask, new_mask), &req)) {
|
||||
/* Need help from migration thread: drop lock and wait. */
|
||||
struct task_struct *mt = rq->migration_thread;
|
||||
|
||||
|
|
@ -7269,19 +7269,19 @@ static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *p)
|
|||
|
||||
again:
|
||||
/* Look for allowed, online CPU in same node. */
|
||||
for_each_cpu_and(dest_cpu, nodemask, cpu_online_mask)
|
||||
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_online_mask);
|
||||
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_online_mask, &p->cpus_allowed);
|
||||
dest_cpu = cpumask_any_and(cpu_active_mask, &p->cpus_allowed);
|
||||
|
||||
/*
|
||||
* Don't tell them about moving exiting tasks or
|
||||
|
|
@ -7310,7 +7310,7 @@ move:
|
|||
*/
|
||||
static void migrate_nr_uninterruptible(struct rq *rq_src)
|
||||
{
|
||||
struct rq *rq_dest = cpu_rq(cpumask_any(cpu_online_mask));
|
||||
struct rq *rq_dest = cpu_rq(cpumask_any(cpu_active_mask));
|
||||
unsigned long flags;
|
||||
|
||||
local_irq_save(flags);
|
||||
|
|
@ -7564,7 +7564,7 @@ static ctl_table *sd_alloc_ctl_cpu_table(int cpu)
|
|||
static struct ctl_table_header *sd_sysctl_header;
|
||||
static void register_sched_domain_sysctl(void)
|
||||
{
|
||||
int i, cpu_num = num_online_cpus();
|
||||
int i, cpu_num = num_possible_cpus();
|
||||
struct ctl_table *entry = sd_alloc_ctl_entry(cpu_num + 1);
|
||||
char buf[32];
|
||||
|
||||
|
|
@ -7574,7 +7574,7 @@ static void register_sched_domain_sysctl(void)
|
|||
if (entry == NULL)
|
||||
return;
|
||||
|
||||
for_each_online_cpu(i) {
|
||||
for_each_possible_cpu(i) {
|
||||
snprintf(buf, 32, "cpu%d", i);
|
||||
entry->procname = kstrdup(buf, GFP_KERNEL);
|
||||
entry->mode = 0555;
|
||||
|
|
@ -9100,7 +9100,7 @@ match1:
|
|||
if (doms_new == NULL) {
|
||||
ndoms_cur = 0;
|
||||
doms_new = &fallback_doms;
|
||||
cpumask_andnot(doms_new[0], cpu_online_mask, cpu_isolated_map);
|
||||
cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map);
|
||||
WARN_ON_ONCE(dattr_new);
|
||||
}
|
||||
|
||||
|
|
@ -9231,8 +9231,10 @@ static int update_sched_domains(struct notifier_block *nfb,
|
|||
switch (action) {
|
||||
case CPU_ONLINE:
|
||||
case CPU_ONLINE_FROZEN:
|
||||
case CPU_DEAD:
|
||||
case CPU_DEAD_FROZEN:
|
||||
case CPU_DOWN_PREPARE:
|
||||
case CPU_DOWN_PREPARE_FROZEN:
|
||||
case CPU_DOWN_FAILED:
|
||||
case CPU_DOWN_FAILED_FROZEN:
|
||||
partition_sched_domains(1, NULL, NULL);
|
||||
return NOTIFY_OK;
|
||||
|
||||
|
|
@ -9279,7 +9281,7 @@ void __init sched_init_smp(void)
|
|||
#endif
|
||||
get_online_cpus();
|
||||
mutex_lock(&sched_domains_mutex);
|
||||
arch_init_sched_domains(cpu_online_mask);
|
||||
arch_init_sched_domains(cpu_active_mask);
|
||||
cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map);
|
||||
if (cpumask_empty(non_isolated_cpus))
|
||||
cpumask_set_cpu(smp_processor_id(), non_isolated_cpus);
|
||||
|
|
|
|||
Загрузка…
Ссылка в новой задаче