5.15-stable review patch. If anyone has any objections, please let me know.
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From: Juri Lelli juri.lelli@redhat.com
[ Upstream commit 440989c10f4e32620e9e2717ca52c3ed7ae11048 ]
A global limits change (sched_rt_handler() logic) currently leaves stale and/or incorrect values in variables related to accounting (e.g. extra_bw).
Properly clean up per runqueue variables before implementing the change and rebuild scheduling domains (so that accounting is also properly restored) after such a change is complete.
Reported-by: Marcel Ziswiler marcel.ziswiler@codethink.co.uk Signed-off-by: Juri Lelli juri.lelli@redhat.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Tested-by: Marcel Ziswiler marcel.ziswiler@codethink.co.uk # nuc & rock5b Link: https://lore.kernel.org/r/20250627115118.438797-4-juri.lelli@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/sched/deadline.c | 4 +++- kernel/sched/rt.c | 6 ++++++ 2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 66eb68c59f0b..708c3960bd06 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -2661,6 +2661,9 @@ void sched_dl_do_global(void) if (global_rt_runtime() != RUNTIME_INF) new_bw = to_ratio(global_rt_period(), global_rt_runtime());
+ for_each_possible_cpu(cpu) + init_dl_rq_bw_ratio(&cpu_rq(cpu)->dl); + for_each_possible_cpu(cpu) { rcu_read_lock_sched();
@@ -2676,7 +2679,6 @@ void sched_dl_do_global(void) raw_spin_unlock_irqrestore(&dl_b->lock, flags);
rcu_read_unlock_sched(); - init_dl_rq_bw_ratio(&cpu_rq(cpu)->dl); } }
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 5fc99dce5145..9720b3c19ab9 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -2861,6 +2861,12 @@ int sched_rt_handler(struct ctl_table *table, int write, void *buffer, } mutex_unlock(&mutex);
+ /* + * After changing maximum available bandwidth for DEADLINE, we need to + * recompute per root domain and per cpus variables accordingly. + */ + rebuild_sched_domains(); + return ret; }