On 3/11/25 7:59 AM, Juri Lelli wrote:
On 10/03/25 20:16, Waiman Long wrote:
On 3/10/25 3:18 PM, Waiman Long wrote:
On 3/10/25 2:54 PM, Dietmar Eggemann wrote:
On 10/03/2025 10:37, Juri Lelli wrote:
Rebuilding of root domains accounting information (total_bw) is
currently broken on some cases, e.g. suspend/resume on aarch64. Problem
Nit: Couldn't spot any arch dependency here. I guess it was just tested
on Arm64 platforms so far.
[...]
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 44093339761c..363ad268a25b 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -2791,6 +2791,7 @@ void partition_sched_domains_locked(int
ndoms_new, cpumask_var_t doms_new[],
ndoms_cur = ndoms_new;
update_sched_domain_debugfs();
+ dl_rebuild_rd_accounting();
Won't dl_rebuild_rd_accounting()'s lockdep_assert_held(&cpuset_mutex)
barf when called via cpuhp's:
sched_cpu_deactivate()
cpuset_cpu_inactive()
partition_sched_domains()
partition_sched_domains_locked()
dl_rebuild_rd_accounting()
?
Good catch. Guess I didn't notice while testing with LOCKDEP as I was
never able to hit this call path on my systems.
Right. If cpuhp_tasks_frozen is true, partition_sched_domains() will be
called without holding cpuset mutex.
Well, I think we will need an additional wrapper in cpuset.c that
acquires the cpuset_mutex first before calling partition_sched_domains()
and use the new wrapper in these cases.
Actually, partition_sched_domains() is called with the special arguments (1,
NULL, NULL) to reset the domain to a single one. So perhaps something like
the following will be enough to avoid this problem.
I think this would work, as we will still rebuild the accounting after
last CPU comes back from suspend. The thing I am still not sure about is
what we want to do in case we have DEADLINE tasks around, since with
this I belive we would be ignoring them and let suspend proceed.
That is the current behavior. You can certainly create a test case to
trigger such condition and see what to do about it. Alternatively, you
can document that and come up with a follow-up patch later on.
Cheers,
Longman
