Disable control files for cgroups-v1, and allow only cgroups-v2. This should
simplify maintaining the code, also because cgroups-v1 is deprecated.
Set the default rt-cgroups runtime to zero, otherwise a cgroup-v1 kernel will
not be able to start SCHED_DEADLINE tasks.
Allow zeroing the runtime of the root control group. This runtime only affects
the available bandwidth of the rt-cgroup hierarchy but not the SCHED_FIFO /
SCHED_RR tasks on the global runqueue.
Notes:
Disabling the root control group bandwidth should not cause any side effect, as
SCHED_FIFO / SCHED_RR tasks do not depend on it since the introduction of
fair_servers.
Signed-off-by: Yuri Andriaccio <yurand2000@gmail.com>
---
kernel/sched/core.c | 22 ++--------------------
kernel/sched/rt.c | 13 +++++--------
kernel/sched/syscalls.c | 2 +-
3 files changed, 8 insertions(+), 29 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index cad2963a2..9c8bc9728 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -8566,7 +8566,7 @@ void __init sched_init(void)
#ifdef CONFIG_RT_GROUP_SCHED
init_dl_bandwidth(&root_task_group.dl_bandwidth,
- global_rt_period(), global_rt_runtime());
+ global_rt_period(), 0);
#endif /* CONFIG_RT_GROUP_SCHED */
#ifdef CONFIG_CGROUP_SCHED
@@ -9198,7 +9198,7 @@ static int cpu_cgroup_can_attach(struct cgroup_taskset *tset)
goto scx_check;
cgroup_taskset_for_each(task, css, tset) {
- if (!sched_rt_can_attach(css_tg(css), task))
+ if (rt_task(task) && !sched_rt_can_attach(css_tg(css), task))
return -EINVAL;
}
scx_check:
@@ -9873,20 +9873,6 @@ static struct cftype cpu_legacy_files[] = {
};
#ifdef CONFIG_RT_GROUP_SCHED
-static struct cftype rt_group_files[] = {
- {
- .name = "rt_runtime_us",
- .read_s64 = cpu_rt_runtime_read,
- .write_s64 = cpu_rt_runtime_write,
- },
- {
- .name = "rt_period_us",
- .read_u64 = cpu_rt_period_read_uint,
- .write_u64 = cpu_rt_period_write_uint,
- },
- { } /* Terminate */
-};
-
# ifdef CONFIG_RT_GROUP_SCHED_DEFAULT_DISABLED
DEFINE_STATIC_KEY_FALSE(rt_group_sched);
# else
@@ -9912,10 +9898,6 @@ __setup("rt_group_sched=", setup_rt_group_sched);
static int __init cpu_rt_group_init(void)
{
- if (!rt_group_sched_enabled())
- return 0;
-
- WARN_ON(cgroup_add_legacy_cftypes(&cpu_cgrp_subsys, rt_group_files));
return 0;
}
subsys_initcall(cpu_rt_group_init);
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 9d17bda66..ce3320f12 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -2197,13 +2197,6 @@ static int tg_set_rt_bandwidth(struct task_group *tg,
{
int i, err = 0;
- /*
- * Disallowing the root group RT runtime is BAD, it would disallow the
- * kernel creating (and or operating) RT threads.
- */
- if (tg == &root_task_group && rt_runtime == 0)
- return -EINVAL;
-
/* No period doesn't make any sense. */
if (rt_period == 0)
return -EINVAL;
@@ -2297,8 +2290,12 @@ static int sched_rt_global_constraints(void)
int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
{
+ /* Allow executing in the root cgroup regardless of allowed bandwidth */
+ if (tg == &root_task_group)
+ return 1;
+
/* Don't accept real-time tasks when there is no way for them to run */
- if (rt_group_sched_enabled() && rt_task(tsk) && tg->dl_bandwidth.dl_runtime == 0)
+ if (rt_group_sched_enabled() && tg->dl_bandwidth.dl_runtime == 0)
return 0;
return 1;
diff --git a/kernel/sched/syscalls.c b/kernel/sched/syscalls.c
index 6c6666b39..45a38fe5e 100644
--- a/kernel/sched/syscalls.c
+++ b/kernel/sched/syscalls.c
@@ -636,7 +636,7 @@ int __sched_setscheduler(struct task_struct *p,
*/
if (rt_group_sched_enabled() &&
dl_bandwidth_enabled() && rt_policy(policy) &&
- task_group(p)->dl_bandwidth.dl_runtime == 0 &&
+ !sched_rt_can_attach(task_group(p), p) &&
!task_group_is_autogroup(task_group(p))) {
retval = -EPERM;
goto unlock;
--
2.49.0