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- Remove a cgroup from under a polling process properly

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- Fix the idle sibling selection
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Merge tag 'sched_urgent_for_v6.5_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler fixes from Borislav Petkov:

 - Remove a cgroup from under a polling process properly

 - Fix the idle sibling selection

* tag 'sched_urgent_for_v6.5_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/psi: use kernfs polling functions for PSI trigger polling
  sched/fair: Use recent_used_cpu to test p->cpus_ptr
This commit is contained in:
Linus Torvalds 2023-07-16 13:22:08 -07:00
commit f61a89ca11
5 changed files with 29 additions and 12 deletions
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5
include/linux/psi.h
View File

@ -23,8 +23,9 @@ void psi_memstall_enter(unsigned long *flags);
void psi_memstall_leave(unsigned long *flags);
int psi_show(struct seq_file *s, struct psi_group *group, enum psi_res res);
struct psi_trigger *psi_trigger_create(struct psi_group *group,
char *buf, enum psi_res res, struct file *file);
struct psi_trigger *psi_trigger_create(struct psi_group *group, char *buf,
enum psi_res res, struct file *file,
struct kernfs_open_file *of);
void psi_trigger_destroy(struct psi_trigger *t);
__poll_t psi_trigger_poll(void **trigger_ptr, struct file *file,

3
include/linux/psi_types.h
View File

@ -137,6 +137,9 @@ struct psi_trigger {
/* Wait queue for polling */
wait_queue_head_t event_wait;
/* Kernfs file for cgroup triggers */
struct kernfs_open_file *of;
/* Pending event flag */
int event;

2
kernel/cgroup/cgroup.c
View File

@ -3730,7 +3730,7 @@ static ssize_t pressure_write(struct kernfs_open_file *of, char *buf,
}
psi = cgroup_psi(cgrp);
new = psi_trigger_create(psi, buf, res, of->file);
new = psi_trigger_create(psi, buf, res, of->file, of);
if (IS_ERR(new)) {
cgroup_put(cgrp);
return PTR_ERR(new);

2
kernel/sched/fair.c
View File

@ -7174,7 +7174,7 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target)
recent_used_cpu != target &&
cpus_share_cache(recent_used_cpu, target) &&
(available_idle_cpu(recent_used_cpu) || sched_idle_cpu(recent_used_cpu)) &&
cpumask_test_cpu(p->recent_used_cpu, p->cpus_ptr) &&
cpumask_test_cpu(recent_used_cpu, p->cpus_ptr) &&
asym_fits_cpu(task_util, util_min, util_max, recent_used_cpu)) {
return recent_used_cpu;
}

23
kernel/sched/psi.c
View File

@ -493,8 +493,12 @@ static u64 update_triggers(struct psi_group *group, u64 now, bool *update_total,
continue;
/* Generate an event */
if (cmpxchg(&t->event, 0, 1) == 0)
if (cmpxchg(&t->event, 0, 1) == 0) {
if (t->of)
kernfs_notify(t->of->kn);
else
wake_up_interruptible(&t->event_wait);
}
t->last_event_time = now;
/* Reset threshold breach flag once event got generated */
t->pending_event = false;
@ -1271,8 +1275,9 @@ int psi_show(struct seq_file *m, struct psi_group *group, enum psi_res res)
return 0;
}
struct psi_trigger *psi_trigger_create(struct psi_group *group,
char *buf, enum psi_res res, struct file *file)
struct psi_trigger *psi_trigger_create(struct psi_group *group, char *buf,
enum psi_res res, struct file *file,
struct kernfs_open_file *of)
{
struct psi_trigger *t;
enum psi_states state;
@ -1331,6 +1336,8 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group,
t->event = 0;
t->last_event_time = 0;
t->of = of;
if (!of)
init_waitqueue_head(&t->event_wait);
t->pending_event = false;
t->aggregator = privileged ? PSI_POLL : PSI_AVGS;
@ -1388,7 +1395,10 @@ void psi_trigger_destroy(struct psi_trigger *t)
* being accessed later. Can happen if cgroup is deleted from under a
* polling process.
*/
wake_up_pollfree(&t->event_wait);
if (t->of)
kernfs_notify(t->of->kn);
else
wake_up_interruptible(&t->event_wait);
if (t->aggregator == PSI_AVGS) {
mutex_lock(&group->avgs_lock);
@ -1465,6 +1475,9 @@ __poll_t psi_trigger_poll(void **trigger_ptr,
if (!t)
return DEFAULT_POLLMASK | EPOLLERR | EPOLLPRI;
if (t->of)
kernfs_generic_poll(t->of, wait);
else
poll_wait(file, &t->event_wait, wait);
if (cmpxchg(&t->event, 1, 0) == 1)
@ -1535,7 +1548,7 @@ static ssize_t psi_write(struct file *file, const char __user *user_buf,
return -EBUSY;
}
new = psi_trigger_create(&psi_system, buf, res, file);
new = psi_trigger_create(&psi_system, buf, res, file, NULL);
if (IS_ERR(new)) {
mutex_unlock(&seq->lock);
return PTR_ERR(new);