diff options
| author | Michal Koutný <mkoutny@suse.com> | 2026-03-23 13:39:37 +0100 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2026-04-08 13:11:44 +0200 |
| commit | 8b016dcec9365675be81d26be88f2c09cf983bd4 (patch) | |
| tree | 333df560af9289255d661b1a2ca10ffaee7014eb | |
| parent | 556146ce5e9476db234134c46ddf0e154ca17028 (diff) | |
sched/rt: Skip group schedulable check with rt_group_sched=0
The warning from the commit 87f1fb77d87a6 ("sched: Add RT_GROUP WARN
checks for non-root task_groups") is wrong -- it assumes that only
task_groups with rt_rq are traversed, however, the schedulability check
would iterate all task_groups even when rt_group_sched=0 is disabled at
boot time but some non-root task_groups exist.
The schedulability check is supposed to validate:
a) that children don't overcommit its parent,
b) no RT task group overcommits global RT limit.
but with rt_group_sched=0 there is no (non-trivial) hierarchy of RT groups,
therefore skip the validation altogether. Otherwise, writes to the
global sched_rt_runtime_us knob will be rejected with incorrect
validation error.
This fix is immaterial with CONFIG_RT_GROUP_SCHED=n.
Fixes: 87f1fb77d87a6 ("sched: Add RT_GROUP WARN checks for non-root task_groups")
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260323-sched-rert_groups-v3-1-1e7d5ed6b249@suse.com
| -rw-r--r-- | kernel/sched/rt.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index a48e86794913..893e54dab13e 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -2690,9 +2690,6 @@ static int tg_rt_schedulable(struct task_group *tg, void *data) tg->rt_bandwidth.rt_runtime && tg_has_rt_tasks(tg)) return -EBUSY; - if (WARN_ON(!rt_group_sched_enabled() && tg != &root_task_group)) - return -EBUSY; - total = to_ratio(period, runtime); /* @@ -2836,6 +2833,8 @@ long sched_group_rt_period(struct task_group *tg) static int sched_rt_global_constraints(void) { int ret = 0; + if (!rt_group_sched_enabled()) + return ret; mutex_lock(&rt_constraints_mutex); ret = __rt_schedulable(NULL, 0, 0); |