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cgroup/cpuset: Free DL BW in case can_attach() fails

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cpuset_can_attach() can fail. Postpone DL BW allocation until all tasks
have been checked. DL BW is not allocated per-task but as a sum over
all DL tasks migrating.

If multiple controllers are attached to the cgroup next to the cpuset
controller a non-cpuset can_attach() can fail. In this case free DL BW
in cpuset_cancel_attach().

Finally, update cpuset DL task count (nr_deadline_tasks) only in
cpuset_attach().

Suggested-by: Waiman Long <longman@redhat.com>
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Dietmar Eggemann 2023-05-08 09:58:54 +02:00 committed by Tejun Heo
parent 85989106fe
commit 2ef269ef1a
3 changed files with 51 additions and 21 deletions
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2
include/linux/sched.h
View File

@ -1852,7 +1852,7 @@ current_restore_flags(unsigned long orig_flags, unsigned long flags)
}
extern int cpuset_cpumask_can_shrink(const struct cpumask *cur, const struct cpumask *trial);
extern int task_can_attach(struct task_struct *p, const struct cpumask *cs_effective_cpus);
extern int task_can_attach(struct task_struct *p);
extern int dl_bw_alloc(int cpu, u64 dl_bw);
extern void dl_bw_free(int cpu, u64 dl_bw);
#ifdef CONFIG_SMP

53
kernel/cgroup/cpuset.c
View File

@ -198,6 +198,8 @@ struct cpuset {
* know when to rebuild associated root domain bandwidth information.
*/
int nr_deadline_tasks;
int nr_migrate_dl_tasks;
u64 sum_migrate_dl_bw;
/* Invalid partition error code, not lock protected */
enum prs_errcode prs_err;
@ -2496,16 +2498,23 @@ static int cpuset_can_attach_check(struct cpuset *cs)
return 0;
}
static void reset_migrate_dl_data(struct cpuset *cs)
{
cs->nr_migrate_dl_tasks = 0;
cs->sum_migrate_dl_bw = 0;
}
/* Called by cgroups to determine if a cpuset is usable; cpuset_mutex held */
static int cpuset_can_attach(struct cgroup_taskset *tset)
{
struct cgroup_subsys_state *css;
struct cpuset *cs;
struct cpuset *cs, *oldcs;
struct task_struct *task;
int ret;
/* used later by cpuset_attach() */
cpuset_attach_old_cs = task_cs(cgroup_taskset_first(tset, &css));
oldcs = cpuset_attach_old_cs;
cs = css_cs(css);
mutex_lock(&cpuset_mutex);
@ -2516,7 +2525,7 @@ static int cpuset_can_attach(struct cgroup_taskset *tset)
goto out_unlock;
cgroup_taskset_for_each(task, css, tset) {
ret = task_can_attach(task, cs->effective_cpus);
ret = task_can_attach(task);
if (ret)
goto out_unlock;
ret = security_task_setscheduler(task);
@ -2524,11 +2533,31 @@ static int cpuset_can_attach(struct cgroup_taskset *tset)
goto out_unlock;
if (dl_task(task)) {
cs->nr_deadline_tasks++;
cpuset_attach_old_cs->nr_deadline_tasks--;
cs->nr_migrate_dl_tasks++;
cs->sum_migrate_dl_bw += task->dl.dl_bw;
}
}
if (!cs->nr_migrate_dl_tasks)
goto out_success;
if (!cpumask_intersects(oldcs->effective_cpus, cs->effective_cpus)) {
int cpu = cpumask_any_and(cpu_active_mask, cs->effective_cpus);
if (unlikely(cpu >= nr_cpu_ids)) {
reset_migrate_dl_data(cs);
ret = -EINVAL;
goto out_unlock;
}
ret = dl_bw_alloc(cpu, cs->sum_migrate_dl_bw);
if (ret) {
reset_migrate_dl_data(cs);
goto out_unlock;
}
}
out_success:
/*
* Mark attach is in progress. This makes validate_change() fail
* changes which zero cpus/mems_allowed.
@ -2551,6 +2580,14 @@ static void cpuset_cancel_attach(struct cgroup_taskset *tset)
cs->attach_in_progress--;
if (!cs->attach_in_progress)
wake_up(&cpuset_attach_wq);
if (cs->nr_migrate_dl_tasks) {
int cpu = cpumask_any(cs->effective_cpus);
dl_bw_free(cpu, cs->sum_migrate_dl_bw);
reset_migrate_dl_data(cs);
}
mutex_unlock(&cpuset_mutex);
}
@ -2651,6 +2688,12 @@ static void cpuset_attach(struct cgroup_taskset *tset)
out:
cs->old_mems_allowed = cpuset_attach_nodemask_to;
if (cs->nr_migrate_dl_tasks) {
cs->nr_deadline_tasks += cs->nr_migrate_dl_tasks;
oldcs->nr_deadline_tasks -= cs->nr_migrate_dl_tasks;
reset_migrate_dl_data(cs);
}
cs->attach_in_progress--;
if (!cs->attach_in_progress)
wake_up(&cpuset_attach_wq);
@ -3330,7 +3373,7 @@ static int cpuset_can_fork(struct task_struct *task, struct css_set *cset)
if (ret)
goto out_unlock;
ret = task_can_attach(task, cs->effective_cpus);
ret = task_can_attach(task);
if (ret)
goto out_unlock;

17
kernel/sched/core.c
View File

@ -9294,8 +9294,7 @@ int cpuset_cpumask_can_shrink(const struct cpumask *cur,
return ret;
}
int task_can_attach(struct task_struct *p,
const struct cpumask *cs_effective_cpus)
int task_can_attach(struct task_struct *p)
{
int ret = 0;
@ -9308,21 +9307,9 @@ int task_can_attach(struct task_struct *p,
* success of set_cpus_allowed_ptr() on all attached tasks
* before cpus_mask may be changed.
*/
if (p->flags & PF_NO_SETAFFINITY) {
if (p->flags & PF_NO_SETAFFINITY)
ret = -EINVAL;
goto out;
}
if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span,
cs_effective_cpus)) {
int cpu = cpumask_any_and(cpu_active_mask, cs_effective_cpus);
if (unlikely(cpu >= nr_cpu_ids))
return -EINVAL;
ret = dl_bw_alloc(cpu, p->dl.dl_bw);
}
out:
return ret;
}