When RT_GROUPs are compiled but not exposed, their bandwidth cannot
be configured (and it is not initialized for non-root task_groups neither).
Therefore bypass any checks of task vs task_group bandwidth.
This will achieve behavior very similar to setups that have
!CONFIG_RT_GROUP_SCHED and attach cpu controller to cgroup v2 hierarchy.
(On a related note, this may allow having RT tasks with
CONFIG_RT_GROUP_SCHED and cgroup v2 hierarchy.)
Signed-off-by: Michal Koutný <mkoutny@xxxxxxxx>
---
kernel/sched/core.c | 6 +++++-
kernel/sched/rt.c | 2 +-
kernel/sched/syscalls.c | 3 ++-
3 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index dfd2778622b8b..6e21e0885557d 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -9158,11 +9158,15 @@ static int cpu_cgroup_can_attach(struct cgroup_taskset *tset)
struct task_struct *task;
struct cgroup_subsys_state *css;
+ if (!rt_group_sched_enabled())
+ goto scx_check;
+
cgroup_taskset_for_each(task, css, tset) {
if (!sched_rt_can_attach(css_tg(css), task))
return -EINVAL;
}
-#endif
+scx_check:
+#endif /* CONFIG_RT_GROUP_SCHED */
return scx_cgroup_can_attach(tset);
}
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 923ec978ff756..161d91f7479b4 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -2866,7 +2866,7 @@ static int sched_rt_global_constraints(void)
int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
{
/* Don't accept real-time tasks when there is no way for them to run */
- if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0)
+ if (rt_group_sched_enabled() && rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0)
return 0;
return 1;
diff --git a/kernel/sched/syscalls.c b/kernel/sched/syscalls.c
index 77d0d4a2b68da..80382f5d53a44 100644
--- a/kernel/sched/syscalls.c
+++ b/kernel/sched/syscalls.c
@@ -644,7 +644,8 @@ int __sched_setscheduler(struct task_struct *p,
* Do not allow real-time tasks into groups that have no runtime
* assigned.
*/
- if (rt_bandwidth_enabled() && rt_policy(policy) &&
+ if (rt_group_sched_enabled() &&
+ rt_bandwidth_enabled() && rt_policy(policy) &&
task_group(p)->rt_bandwidth.rt_runtime == 0 &&
!task_group_is_autogroup(task_group(p))) {
retval = -EPERM;
--
2.47.1
