[PATCH v2 0/8] Fix SCHED_DEADLINE bandwidth accounting during suspend

[PATCH v2 0/8] Fix SCHED_DEADLINE bandwidth accounting during suspend

[Juri Lelli]

Hello!

Jon reported [1] a suspend regression on a Tegra board configured to
boot with isolcpus and bisected it to commit 53916d5fd3c0
("sched/deadline: Check bandwidth overflow earlier for hotplug").

Root cause analysis pointed out that we are currently failing to
correctly clear and restore bandwidth accounting on root domains after
changes that initiate from partition_sched_domains(), as it is the case
for suspend operations on that board.

This is v2 [2] of the proposed approach to fix the issue. With respect
to v1, the following implements the approach by:

- 01: filter out DEADLINE special tasks
- 02: preparatory wrappers to be able to grab sched_domains_mutex on
      UP (remove !SMP wrappers - Waiman)
- 03: generalize unique visiting of root domains so that we can
      re-use the mechanism elsewhere
- 04: the bulk of the approach, clean and rebuild after changes
- 05: clean up a now redundant call
- 06: remove partition_and_rebuild_sched_domains() (Waiman)
- 07: stop exposing partition_sched_domains_locked (Waiman)

Please test and review. The set is also available at

git@github.com:jlelli/linux.git upstream/deadline/domains-suspend

Best,
Juri

1 - https://lore.kernel.org/lkml/ba51a43f-796d-4b79-808a-b8185905638a@nvidia.com/
2 - v1 https://lore.kernel.org/lkml/20250304084045.62554-1-juri.lelli@redhat.com

Juri Lelli (8):
  sched/deadline: Ignore special tasks when rebuilding domains
  sched/topology: Wrappers for sched_domains_mutex
  sched/deadline: Generalize unique visiting of root domains
  sched/deadline: Rebuild root domain accounting after every update
  sched/topology: Remove redundant dl_clear_root_domain call
  cgroup/cpuset: Remove partition_and_rebuild_sched_domains
  sched/topology: Stop exposing partition_sched_domains_locked
  include/{topology,cpuset}: Move dl_rebuild_rd_accounting to cpuset.h

 include/linux/cpuset.h         |  5 +++++
 include/linux/sched.h          |  2 ++
 include/linux/sched/deadline.h |  7 +++++++
 include/linux/sched/topology.h | 10 ---------
 kernel/cgroup/cpuset.c         | 27 +++++++++----------------
 kernel/sched/core.c            |  4 ++--
 kernel/sched/deadline.c        | 37 ++++++++++++++++++++--------------
 kernel/sched/debug.c           |  8 ++++----
 kernel/sched/rt.c              |  2 ++
 kernel/sched/sched.h           |  2 +-
 kernel/sched/topology.c        | 32 +++++++++++++----------------
 11 files changed, 69 insertions(+), 67 deletions(-)


base-commit: 48a5eed9ad584315c30ed35204510536235ce402
-- 
2.48.1

[PATCH v2 1/8] sched/deadline: Ignore special tasks when rebuilding domains

[Juri Lelli]

SCHED_DEADLINE special tasks get a fake bandwidth that is only used to
make sure sleeping and priority inheritance 'work', but it is ignored
for runtime enforcement and admission control.

Be consistent with it also when rebuilding root domains.

Reported-by: Jon Hunter <jonathanh@nvidia.com>
Fixes: 53916d5fd3c0 ("sched/deadline: Check bandwidth overflow earlier for hotplug")
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
---
 kernel/sched/deadline.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 38e4537790af..ab565a151355 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -2956,7 +2956,7 @@ void dl_add_task_root_domain(struct task_struct *p)
 	struct dl_bw *dl_b;
 
 	raw_spin_lock_irqsave(&p->pi_lock, rf.flags);
-	if (!dl_task(p)) {
+	if (!dl_task(p) || dl_entity_is_special(&p->dl)) {
 		raw_spin_unlock_irqrestore(&p->pi_lock, rf.flags);
 		return;
 	}
-- 
2.48.1

[PATCH v2 2/8] sched/topology: Wrappers for sched_domains_mutex

[Juri Lelli]

Create wrappers for sched_domains_mutex so that it can transparently be
used on both CONFIG_SMP and !CONFIG_SMP, as some function will need to
do.

Reported-by: Jon Hunter <jonathanh@nvidia.com>
Fixes: 53916d5fd3c0 ("sched/deadline: Check bandwidth overflow earlier for hotplug")
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
---
v1 -> v2: Remove wrappers for the !SMP case as all users are not defined
          either in that case
---
 include/linux/sched.h   |  2 ++
 kernel/cgroup/cpuset.c  |  4 ++--
 kernel/sched/core.c     |  4 ++--
 kernel/sched/debug.c    |  8 ++++----
 kernel/sched/topology.c | 12 ++++++++++--
 5 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 9632e3318e0d..d5f8c161d852 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -383,6 +383,8 @@ enum uclamp_id {
 extern struct root_domain def_root_domain;
 extern struct mutex sched_domains_mutex;
 #endif
+extern void sched_domains_mutex_lock(void);
+extern void sched_domains_mutex_unlock(void);
 
 struct sched_param {
 	int sched_priority;
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 0f910c828973..f87526edb2a4 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -994,10 +994,10 @@ static void
 partition_and_rebuild_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
 				    struct sched_domain_attr *dattr_new)
 {
-	mutex_lock(&sched_domains_mutex);
+	sched_domains_mutex_lock();
 	partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);
 	dl_rebuild_rd_accounting();
-	mutex_unlock(&sched_domains_mutex);
+	sched_domains_mutex_unlock();
 }
 
 /*
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 67189907214d..58593f4d09a1 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -8424,9 +8424,9 @@ void __init sched_init_smp(void)
 	 * CPU masks are stable and all blatant races in the below code cannot
 	 * happen.
 	 */
-	mutex_lock(&sched_domains_mutex);
+	sched_domains_mutex_lock();
 	sched_init_domains(cpu_active_mask);
-	mutex_unlock(&sched_domains_mutex);
+	sched_domains_mutex_unlock();
 
 	/* Move init over to a non-isolated CPU */
 	if (set_cpus_allowed_ptr(current, housekeeping_cpumask(HK_TYPE_DOMAIN)) < 0)
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index ef047add7f9e..a0893a483d35 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -292,7 +292,7 @@ static ssize_t sched_verbose_write(struct file *filp, const char __user *ubuf,
 	bool orig;
 
 	cpus_read_lock();
-	mutex_lock(&sched_domains_mutex);
+	sched_domains_mutex_lock();
 
 	orig = sched_debug_verbose;
 	result = debugfs_write_file_bool(filp, ubuf, cnt, ppos);
@@ -304,7 +304,7 @@ static ssize_t sched_verbose_write(struct file *filp, const char __user *ubuf,
 		sd_dentry = NULL;
 	}
 
-	mutex_unlock(&sched_domains_mutex);
+	sched_domains_mutex_unlock();
 	cpus_read_unlock();
 
 	return result;
@@ -515,9 +515,9 @@ static __init int sched_init_debug(void)
 	debugfs_create_u32("migration_cost_ns", 0644, debugfs_sched, &sysctl_sched_migration_cost);
 	debugfs_create_u32("nr_migrate", 0644, debugfs_sched, &sysctl_sched_nr_migrate);
 
-	mutex_lock(&sched_domains_mutex);
+	sched_domains_mutex_lock();
 	update_sched_domain_debugfs();
-	mutex_unlock(&sched_domains_mutex);
+	sched_domains_mutex_unlock();
 #endif
 
 #ifdef CONFIG_NUMA_BALANCING
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index c49aea8c1025..296ff2acfd32 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -6,6 +6,14 @@
 #include <linux/bsearch.h>
 
 DEFINE_MUTEX(sched_domains_mutex);
+void sched_domains_mutex_lock(void)
+{
+	mutex_lock(&sched_domains_mutex);
+}
+void sched_domains_mutex_unlock(void)
+{
+	mutex_unlock(&sched_domains_mutex);
+}
 
 /* Protected by sched_domains_mutex: */
 static cpumask_var_t sched_domains_tmpmask;
@@ -2791,7 +2799,7 @@ void partition_sched_domains_locked(int ndoms_new, cpumask_var_t doms_new[],
 void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
 			     struct sched_domain_attr *dattr_new)
 {
-	mutex_lock(&sched_domains_mutex);
+	sched_domains_mutex_lock();
 	partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);
-	mutex_unlock(&sched_domains_mutex);
+	sched_domains_mutex_unlock();
 }
-- 
2.48.1

[PATCH v2 3/8] sched/deadline: Generalize unique visiting of root domains

[Juri Lelli]

Bandwidth checks and updates that work on root domains currently employ
a cookie mechanism for efficiency. This mechanism is very much tied to
when root domains are first created and initialized.

Generalize the cookie mechanism so that it can be used also later at
runtime while updating root domains. Also, additionally guard it with
sched_domains_mutex, since domains need to be stable while updating them
(and it will be required for further dynamic changes).

Reported-by: Jon Hunter <jonathanh@nvidia.com>
Fixes: 53916d5fd3c0 ("sched/deadline: Check bandwidth overflow earlier for hotplug")
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
---
 include/linux/sched/deadline.h |  3 +++
 kernel/sched/deadline.c        | 23 +++++++++++++----------
 kernel/sched/rt.c              |  2 ++
 kernel/sched/sched.h           |  2 +-
 kernel/sched/topology.c        |  2 +-
 5 files changed, 20 insertions(+), 12 deletions(-)

diff --git a/include/linux/sched/deadline.h b/include/linux/sched/deadline.h
index 3a912ab42bb5..6ec578600b24 100644
--- a/include/linux/sched/deadline.h
+++ b/include/linux/sched/deadline.h
@@ -37,4 +37,7 @@ extern void dl_clear_root_domain(struct root_domain *rd);
 
 #endif /* CONFIG_SMP */
 
+extern u64 dl_cookie;
+extern bool dl_bw_visited(int cpu, u64 cookie);
+
 #endif /* _LINUX_SCHED_DEADLINE_H */
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index ab565a151355..339434271cba 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -166,14 +166,14 @@ static inline unsigned long dl_bw_capacity(int i)
 	}
 }
 
-static inline bool dl_bw_visited(int cpu, u64 gen)
+static inline bool dl_bw_visited(int cpu, u64 cookie)
 {
 	struct root_domain *rd = cpu_rq(cpu)->rd;
 
-	if (rd->visit_gen == gen)
+	if (rd->visit_cookie == cookie)
 		return true;
 
-	rd->visit_gen = gen;
+	rd->visit_cookie = cookie;
 	return false;
 }
 
@@ -207,7 +207,7 @@ static inline unsigned long dl_bw_capacity(int i)
 	return SCHED_CAPACITY_SCALE;
 }
 
-static inline bool dl_bw_visited(int cpu, u64 gen)
+static inline bool dl_bw_visited(int cpu, u64 cookie)
 {
 	return false;
 }
@@ -3171,15 +3171,18 @@ DEFINE_SCHED_CLASS(dl) = {
 #endif
 };
 
-/* Used for dl_bw check and update, used under sched_rt_handler()::mutex */
-static u64 dl_generation;
+/*
+ * Used for dl_bw check and update, used under sched_rt_handler()::mutex and
+ * sched_domains_mutex.
+ */
+u64 dl_cookie;
 
 int sched_dl_global_validate(void)
 {
 	u64 runtime = global_rt_runtime();
 	u64 period = global_rt_period();
 	u64 new_bw = to_ratio(period, runtime);
-	u64 gen = ++dl_generation;
+	u64 cookie = ++dl_cookie;
 	struct dl_bw *dl_b;
 	int cpu, cpus, ret = 0;
 	unsigned long flags;
@@ -3192,7 +3195,7 @@ int sched_dl_global_validate(void)
 	for_each_possible_cpu(cpu) {
 		rcu_read_lock_sched();
 
-		if (dl_bw_visited(cpu, gen))
+		if (dl_bw_visited(cpu, cookie))
 			goto next;
 
 		dl_b = dl_bw_of(cpu);
@@ -3229,7 +3232,7 @@ static void init_dl_rq_bw_ratio(struct dl_rq *dl_rq)
 void sched_dl_do_global(void)
 {
 	u64 new_bw = -1;
-	u64 gen = ++dl_generation;
+	u64 cookie = ++dl_cookie;
 	struct dl_bw *dl_b;
 	int cpu;
 	unsigned long flags;
@@ -3240,7 +3243,7 @@ void sched_dl_do_global(void)
 	for_each_possible_cpu(cpu) {
 		rcu_read_lock_sched();
 
-		if (dl_bw_visited(cpu, gen)) {
+		if (dl_bw_visited(cpu, cookie)) {
 			rcu_read_unlock_sched();
 			continue;
 		}
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 4b8e33c615b1..8cebe71d2bb1 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -2910,6 +2910,7 @@ static int sched_rt_handler(const struct ctl_table *table, int write, void *buff
 	int ret;
 
 	mutex_lock(&mutex);
+	sched_domains_mutex_lock();
 	old_period = sysctl_sched_rt_period;
 	old_runtime = sysctl_sched_rt_runtime;
 
@@ -2936,6 +2937,7 @@ static int sched_rt_handler(const struct ctl_table *table, int write, void *buff
 		sysctl_sched_rt_period = old_period;
 		sysctl_sched_rt_runtime = old_runtime;
 	}
+	sched_domains_mutex_unlock();
 	mutex_unlock(&mutex);
 
 	return ret;
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index c8512a9fb022..c978abe38c07 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -998,7 +998,7 @@ struct root_domain {
 	 * Also, some corner cases, like 'wrap around' is dangerous, but given
 	 * that u64 is 'big enough'. So that shouldn't be a concern.
 	 */
-	u64 visit_gen;
+	u64 visit_cookie;
 
 #ifdef HAVE_RT_PUSH_IPI
 	/*
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 296ff2acfd32..44093339761c 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -568,7 +568,7 @@ static int init_rootdomain(struct root_domain *rd)
 	rd->rto_push_work = IRQ_WORK_INIT_HARD(rto_push_irq_work_func);
 #endif
 
-	rd->visit_gen = 0;
+	rd->visit_cookie = 0;
 	init_dl_bw(&rd->dl_bw);
 	if (cpudl_init(&rd->cpudl) != 0)
 		goto free_rto_mask;
-- 
2.48.1

[PATCH v2 4/8] sched/deadline: Rebuild root domain accounting after every update

[Juri Lelli]

Rebuilding of root domains accounting information (total_bw) is
currently broken on some cases, e.g. suspend/resume on aarch64. Problem
is that the way we keep track of domain changes and try to add bandwidth
back is convoluted and fragile.

Fix it by simplify things by making sure bandwidth accounting is cleared
and completely restored after root domains changes (after root domains
are again stable).

Reported-by: Jon Hunter <jonathanh@nvidia.com>
Fixes: 53916d5fd3c0 ("sched/deadline: Check bandwidth overflow earlier for hotplug")
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
---
 include/linux/sched/deadline.h |  4 ++++
 include/linux/sched/topology.h |  2 ++
 kernel/cgroup/cpuset.c         | 16 +++++++++-------
 kernel/sched/deadline.c        | 16 ++++++++++------
 kernel/sched/topology.c        |  1 +
 5 files changed, 26 insertions(+), 13 deletions(-)

diff --git a/include/linux/sched/deadline.h b/include/linux/sched/deadline.h
index 6ec578600b24..a780068aa1a5 100644
--- a/include/linux/sched/deadline.h
+++ b/include/linux/sched/deadline.h
@@ -34,6 +34,10 @@ static inline bool dl_time_before(u64 a, u64 b)
 struct root_domain;
 extern void dl_add_task_root_domain(struct task_struct *p);
 extern void dl_clear_root_domain(struct root_domain *rd);
+extern void dl_clear_root_domain_cpu(int cpu);
+
+extern u64 dl_cookie;
+extern bool dl_bw_visited(int cpu, u64 gen);
 
 #endif /* CONFIG_SMP */
 
diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h
index 7f3dbafe1817..1622232bd08b 100644
--- a/include/linux/sched/topology.h
+++ b/include/linux/sched/topology.h
@@ -166,6 +166,8 @@ static inline struct cpumask *sched_domain_span(struct sched_domain *sd)
 	return to_cpumask(sd->span);
 }
 
+extern void dl_rebuild_rd_accounting(void);
+
 extern void partition_sched_domains_locked(int ndoms_new,
 					   cpumask_var_t doms_new[],
 					   struct sched_domain_attr *dattr_new);
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index f87526edb2a4..f66b2aefdc04 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -954,10 +954,12 @@ static void dl_update_tasks_root_domain(struct cpuset *cs)
 	css_task_iter_end(&it);
 }
 
-static void dl_rebuild_rd_accounting(void)
+void dl_rebuild_rd_accounting(void)
 {
 	struct cpuset *cs = NULL;
 	struct cgroup_subsys_state *pos_css;
+	int cpu;
+	u64 cookie = ++dl_cookie;
 
 	lockdep_assert_held(&cpuset_mutex);
 	lockdep_assert_cpus_held();
@@ -965,11 +967,12 @@ static void dl_rebuild_rd_accounting(void)
 
 	rcu_read_lock();
 
-	/*
-	 * Clear default root domain DL accounting, it will be computed again
-	 * if a task belongs to it.
-	 */
-	dl_clear_root_domain(&def_root_domain);
+	for_each_possible_cpu(cpu) {
+		if (dl_bw_visited(cpu, cookie))
+			continue;
+
+		dl_clear_root_domain_cpu(cpu);
+	}
 
 	cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) {
 
@@ -996,7 +999,6 @@ partition_and_rebuild_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
 {
 	sched_domains_mutex_lock();
 	partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);
-	dl_rebuild_rd_accounting();
 	sched_domains_mutex_unlock();
 }
 
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 339434271cba..17b040c92885 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -166,7 +166,7 @@ static inline unsigned long dl_bw_capacity(int i)
 	}
 }
 
-static inline bool dl_bw_visited(int cpu, u64 cookie)
+bool dl_bw_visited(int cpu, u64 cookie)
 {
 	struct root_domain *rd = cpu_rq(cpu)->rd;
 
@@ -207,7 +207,7 @@ static inline unsigned long dl_bw_capacity(int i)
 	return SCHED_CAPACITY_SCALE;
 }
 
-static inline bool dl_bw_visited(int cpu, u64 cookie)
+bool dl_bw_visited(int cpu, u64 cookie)
 {
 	return false;
 }
@@ -2981,18 +2981,22 @@ void dl_clear_root_domain(struct root_domain *rd)
 	rd->dl_bw.total_bw = 0;
 
 	/*
-	 * dl_server bandwidth is only restored when CPUs are attached to root
-	 * domains (after domains are created or CPUs moved back to the
-	 * default root doamin).
+	 * dl_servers are not tasks. Since dl_add_task_root_domanin ignores
+	 * them, we need to account for them here explicitly.
 	 */
 	for_each_cpu(i, rd->span) {
 		struct sched_dl_entity *dl_se = &cpu_rq(i)->fair_server;
 
 		if (dl_server(dl_se) && cpu_active(i))
-			rd->dl_bw.total_bw += dl_se->dl_bw;
+			__dl_add(&rd->dl_bw, dl_se->dl_bw, dl_bw_cpus(i));
 	}
 }
 
+void dl_clear_root_domain_cpu(int cpu)
+{
+	dl_clear_root_domain(cpu_rq(cpu)->rd);
+}
+
 #endif /* CONFIG_SMP */
 
 static void switched_from_dl(struct rq *rq, struct task_struct *p)
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();
 }
 
 /*
-- 
2.48.1

[PATCH v2 5/8] sched/topology: Remove redundant dl_clear_root_domain call

[Juri Lelli]

We completely clean and restore root domains bandwidth accounting after
every root domains change, so the dl_clear_root_domain() call in
partition_sched_domains_locked() is redundant.

Remove it.

Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
---
 kernel/sched/topology.c | 15 +--------------
 1 file changed, 1 insertion(+), 14 deletions(-)

diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 363ad268a25b..df2d94a57e84 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -2720,21 +2720,8 @@ void partition_sched_domains_locked(int ndoms_new, cpumask_var_t doms_new[],
 	for (i = 0; i < ndoms_cur; i++) {
 		for (j = 0; j < n && !new_topology; j++) {
 			if (cpumask_equal(doms_cur[i], doms_new[j]) &&
-			    dattrs_equal(dattr_cur, i, dattr_new, j)) {
-				struct root_domain *rd;
-
-				/*
-				 * This domain won't be destroyed and as such
-				 * its dl_bw->total_bw needs to be cleared.
-				 * Tasks contribution will be then recomputed
-				 * in function dl_update_tasks_root_domain(),
-				 * dl_servers contribution in function
-				 * dl_restore_server_root_domain().
-				 */
-				rd = cpu_rq(cpumask_any(doms_cur[i]))->rd;
-				dl_clear_root_domain(rd);
+			    dattrs_equal(dattr_cur, i, dattr_new, j))
 				goto match1;
-			}
 		}
 		/* No match - a current sched domain not in new doms_new[] */
 		detach_destroy_domains(doms_cur[i]);
-- 
2.48.1

[PATCH v2 6/8] cgroup/cpuset: Remove partition_and_rebuild_sched_domains

[Juri Lelli]

partition_and_rebuild_sched_domains() and partition_sched_domains() are
now equivalent.

Remove the former as a nice clean up.

Suggested-by: Waiman Long <llong@redhat.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
---
 kernel/cgroup/cpuset.c | 11 +----------
 1 file changed, 1 insertion(+), 10 deletions(-)

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index f66b2aefdc04..7995cd58a01b 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -993,15 +993,6 @@ void dl_rebuild_rd_accounting(void)
 	rcu_read_unlock();
 }
 
-static void
-partition_and_rebuild_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
-				    struct sched_domain_attr *dattr_new)
-{
-	sched_domains_mutex_lock();
-	partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);
-	sched_domains_mutex_unlock();
-}
-
 /*
  * Rebuild scheduler domains.
  *
@@ -1063,7 +1054,7 @@ void rebuild_sched_domains_locked(void)
 	ndoms = generate_sched_domains(&doms, &attr);
 
 	/* Have scheduler rebuild the domains */
-	partition_and_rebuild_sched_domains(ndoms, doms, attr);
+	partition_sched_domains(ndoms, doms, attr);
 }
 #else /* !CONFIG_SMP */
 void rebuild_sched_domains_locked(void)
-- 
2.48.1

[PATCH v2 7/8] sched/topology: Stop exposing partition_sched_domains_locked

[Juri Lelli]

The are no callers of partition_sched_domains_locked() outside
topology.c.

Stop exposing such function.

Suggested-by: Waiman Long <llong@redhat.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
---
 include/linux/sched/topology.h | 10 ----------
 kernel/sched/topology.c        |  2 +-
 2 files changed, 1 insertion(+), 11 deletions(-)

diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h
index 1622232bd08b..96e69bfc3c8a 100644
--- a/include/linux/sched/topology.h
+++ b/include/linux/sched/topology.h
@@ -168,10 +168,6 @@ static inline struct cpumask *sched_domain_span(struct sched_domain *sd)
 
 extern void dl_rebuild_rd_accounting(void);
 
-extern void partition_sched_domains_locked(int ndoms_new,
-					   cpumask_var_t doms_new[],
-					   struct sched_domain_attr *dattr_new);
-
 extern void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
 				    struct sched_domain_attr *dattr_new);
 
@@ -212,12 +208,6 @@ extern void __init set_sched_topology(struct sched_domain_topology_level *tl);
 
 struct sched_domain_attr;
 
-static inline void
-partition_sched_domains_locked(int ndoms_new, cpumask_var_t doms_new[],
-			       struct sched_domain_attr *dattr_new)
-{
-}
-
 static inline void
 partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
 			struct sched_domain_attr *dattr_new)
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index df2d94a57e84..95bde793651c 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -2688,7 +2688,7 @@ static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
  *
  * Call with hotplug lock and sched_domains_mutex held
  */
-void partition_sched_domains_locked(int ndoms_new, cpumask_var_t doms_new[],
+static void partition_sched_domains_locked(int ndoms_new, cpumask_var_t doms_new[],
 				    struct sched_domain_attr *dattr_new)
 {
 	bool __maybe_unused has_eas = false;
-- 
2.48.1

[PATCH v2 8/8] include/{topology,cpuset}: Move dl_rebuild_rd_accounting to cpuset.h

[Juri Lelli]

dl_rebuild_rd_accounting() is defined in cpuset.c, so it makes more
sense to move related declarations to cpuset.h.

Implement the move.

Suggested-by: Waiman Long <llong@redhat.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
---
 include/linux/cpuset.h         | 5 +++++
 include/linux/sched/topology.h | 2 --
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
index 835e7b793f6a..c414daa7d503 100644
--- a/include/linux/cpuset.h
+++ b/include/linux/cpuset.h
@@ -125,6 +125,7 @@ static inline int cpuset_do_page_mem_spread(void)
 
 extern bool current_cpuset_is_being_rebound(void);
 
+extern void dl_rebuild_rd_accounting(void);
 extern void rebuild_sched_domains(void);
 
 extern void cpuset_print_current_mems_allowed(void);
@@ -259,6 +260,10 @@ static inline bool current_cpuset_is_being_rebound(void)
 	return false;
 }
 
+static inline void dl_rebuild_rd_accounting(void)
+{
+}
+
 static inline void rebuild_sched_domains(void)
 {
 	partition_sched_domains(1, NULL, NULL);
diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h
index 96e69bfc3c8a..51f7b8169515 100644
--- a/include/linux/sched/topology.h
+++ b/include/linux/sched/topology.h
@@ -166,8 +166,6 @@ static inline struct cpumask *sched_domain_span(struct sched_domain *sd)
 	return to_cpumask(sd->span);
 }
 
-extern void dl_rebuild_rd_accounting(void);
-
 extern void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
 				    struct sched_domain_attr *dattr_new);
 
-- 
2.48.1

Re: [PATCH v2 3/8] sched/deadline: Generalize unique visiting of root domains

[Shrikanth Hegde]

On 3/6/25 19:40, Juri Lelli wrote:
> Bandwidth checks and updates that work on root domains currently employ
> a cookie mechanism for efficiency. This mechanism is very much tied to
> when root domains are first created and initialized.
> 
> Generalize the cookie mechanism so that it can be used also later at
> runtime while updating root domains. Also, additionally guard it with
> sched_domains_mutex, since domains need to be stable while updating them
> (and it will be required for further dynamic changes).
> 
> Reported-by: Jon Hunter <jonathanh@nvidia.com>
> Fixes: 53916d5fd3c0 ("sched/deadline: Check bandwidth overflow earlier for hotplug")
> Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
> ---
>   include/linux/sched/deadline.h |  3 +++
>   kernel/sched/deadline.c        | 23 +++++++++++++----------
>   kernel/sched/rt.c              |  2 ++
>   kernel/sched/sched.h           |  2 +-
>   kernel/sched/topology.c        |  2 +-
>   5 files changed, 20 insertions(+), 12 deletions(-)
> 
> diff --git a/include/linux/sched/deadline.h b/include/linux/sched/deadline.h
> index 3a912ab42bb5..6ec578600b24 100644
> --- a/include/linux/sched/deadline.h
> +++ b/include/linux/sched/deadline.h
> @@ -37,4 +37,7 @@ extern void dl_clear_root_domain(struct root_domain *rd);
>   
>   #endif /* CONFIG_SMP */
>   
> +extern u64 dl_cookie;
> +extern bool dl_bw_visited(int cpu, u64 cookie);
> +
>   #endif /* _LINUX_SCHED_DEADLINE_H */
> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
> index ab565a151355..339434271cba 100644
> --- a/kernel/sched/deadline.c
> +++ b/kernel/sched/deadline.c
> @@ -166,14 +166,14 @@ static inline unsigned long dl_bw_capacity(int i)
>   	}
>   }
>   
> -static inline bool dl_bw_visited(int cpu, u64 gen)
> +static inline bool dl_bw_visited(int cpu, u64 cookie)
>   {
>   	struct root_domain *rd = cpu_rq(cpu)->rd;
>   
> -	if (rd->visit_gen == gen)
> +	if (rd->visit_cookie == cookie)
>   		return true;
>   
> -	rd->visit_gen = gen;
> +	rd->visit_cookie = cookie;
>   	return false;
>   }
>   
> @@ -207,7 +207,7 @@ static inline unsigned long dl_bw_capacity(int i)
>   	return SCHED_CAPACITY_SCALE;
>   }
>   
> -static inline bool dl_bw_visited(int cpu, u64 gen)
> +static inline bool dl_bw_visited(int cpu, u64 cookie)
>   {
>   	return false;
>   }
> @@ -3171,15 +3171,18 @@ DEFINE_SCHED_CLASS(dl) = {
>   #endif
>   };
>   
> -/* Used for dl_bw check and update, used under sched_rt_handler()::mutex */
> -static u64 dl_generation;
> +/*
> + * Used for dl_bw check and update, used under sched_rt_handler()::mutex and
> + * sched_domains_mutex.
> + */
> +u64 dl_cookie;
>   
>   int sched_dl_global_validate(void)
>   {
>   	u64 runtime = global_rt_runtime();
>   	u64 period = global_rt_period();
>   	u64 new_bw = to_ratio(period, runtime);
> -	u64 gen = ++dl_generation;
> +	u64 cookie = ++dl_cookie;
>   	struct dl_bw *dl_b;
>   	int cpu, cpus, ret = 0;
>   	unsigned long flags;
> @@ -3192,7 +3195,7 @@ int sched_dl_global_validate(void)
>   	for_each_possible_cpu(cpu) {

This has been changed in 14672f059d83f591afb2ee1fff56858efe055e5a to 
online CPUs. So patch didn't apply cleanly to me.

>   		rcu_read_lock_sched();
>   
> -		if (dl_bw_visited(cpu, gen))
> +		if (dl_bw_visited(cpu, cookie))
>   			goto next;
>   
>   		dl_b = dl_bw_of(cpu);
> @@ -3229,7 +3232,7 @@ static void init_dl_rq_bw_ratio(struct dl_rq *dl_rq)
>   void sched_dl_do_global(void)
>   {
>   	u64 new_bw = -1;
> -	u64 gen = ++dl_generation;
> +	u64 cookie = ++dl_cookie;
>   	struct dl_bw *dl_b;
>   	int cpu;
>   	unsigned long flags;
> @@ -3240,7 +3243,7 @@ void sched_dl_do_global(void)
>   	for_each_possible_cpu(cpu) {
>   		rcu_read_lock_sched();
>   
> -		if (dl_bw_visited(cpu, gen)) {
> +		if (dl_bw_visited(cpu, cookie)) {
>   			rcu_read_unlock_sched();
>   			continue;
>   		}
> diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
> index 4b8e33c615b1..8cebe71d2bb1 100644
> --- a/kernel/sched/rt.c
> +++ b/kernel/sched/rt.c
> @@ -2910,6 +2910,7 @@ static int sched_rt_handler(const struct ctl_table *table, int write, void *buff
>   	int ret;
>   
>   	mutex_lock(&mutex);
> +	sched_domains_mutex_lock();
>   	old_period = sysctl_sched_rt_period;
>   	old_runtime = sysctl_sched_rt_runtime;
>   
> @@ -2936,6 +2937,7 @@ static int sched_rt_handler(const struct ctl_table *table, int write, void *buff
>   		sysctl_sched_rt_period = old_period;
>   		sysctl_sched_rt_runtime = old_runtime;
>   	}
> +	sched_domains_mutex_unlock();
>   	mutex_unlock(&mutex);
>   
>   	return ret;
> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> index c8512a9fb022..c978abe38c07 100644
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -998,7 +998,7 @@ struct root_domain {
>   	 * Also, some corner cases, like 'wrap around' is dangerous, but given
>   	 * that u64 is 'big enough'. So that shouldn't be a concern.
>   	 */
> -	u64 visit_gen;
> +	u64 visit_cookie;
>   
>   #ifdef HAVE_RT_PUSH_IPI
>   	/*
> diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
> index 296ff2acfd32..44093339761c 100644
> --- a/kernel/sched/topology.c
> +++ b/kernel/sched/topology.c
> @@ -568,7 +568,7 @@ static int init_rootdomain(struct root_domain *rd)
>   	rd->rto_push_work = IRQ_WORK_INIT_HARD(rto_push_irq_work_func);
>   #endif
>   
> -	rd->visit_gen = 0;
> +	rd->visit_cookie = 0;
>   	init_dl_bw(&rd->dl_bw);
>   	if (cpudl_init(&rd->cpudl) != 0)
>   		goto free_rto_mask;

Re: [PATCH v2 4/8] sched/deadline: Rebuild root domain accounting after every update

[Shrikanth Hegde]

Hi Juri.

On 3/6/25 19:40, Juri Lelli wrote:
> Rebuilding of root domains accounting information (total_bw) is
> currently broken on some cases, e.g. suspend/resume on aarch64. Problem
> is that the way we keep track of domain changes and try to add bandwidth
> back is convoluted and fragile.
> 
> Fix it by simplify things by making sure bandwidth accounting is cleared
> and completely restored after root domains changes (after root domains
> are again stable).
> 
> Reported-by: Jon Hunter <jonathanh@nvidia.com>
> Fixes: 53916d5fd3c0 ("sched/deadline: Check bandwidth overflow earlier for hotplug")
> Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
> ---
>   include/linux/sched/deadline.h |  4 ++++
>   include/linux/sched/topology.h |  2 ++
>   kernel/cgroup/cpuset.c         | 16 +++++++++-------
>   kernel/sched/deadline.c        | 16 ++++++++++------
>   kernel/sched/topology.c        |  1 +
>   5 files changed, 26 insertions(+), 13 deletions(-)
> 
> diff --git a/include/linux/sched/deadline.h b/include/linux/sched/deadline.h
> index 6ec578600b24..a780068aa1a5 100644
> --- a/include/linux/sched/deadline.h
> +++ b/include/linux/sched/deadline.h
> @@ -34,6 +34,10 @@ static inline bool dl_time_before(u64 a, u64 b)
>   struct root_domain;
>   extern void dl_add_task_root_domain(struct task_struct *p);
>   extern void dl_clear_root_domain(struct root_domain *rd);
> +extern void dl_clear_root_domain_cpu(int cpu);
> +
> +extern u64 dl_cookie;
> +extern bool dl_bw_visited(int cpu, u64 gen);

Is this needed? There is same declaration outside of CONFIG_SMP done in 
patch 3/8.

>   
>   #endif /* CONFIG_SMP */
>   
> diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h
> index 7f3dbafe1817..1622232bd08b 100644
> --- a/include/linux/sched/topology.h
> +++ b/include/linux/sched/topology.h
> @@ -166,6 +166,8 @@ static inline struct cpumask *sched_domain_span(struct sched_domain *sd)
>   	return to_cpumask(sd->span);
>   }
>   
> +extern void dl_rebuild_rd_accounting(void);
> +
>   extern void partition_sched_domains_locked(int ndoms_new,
>   					   cpumask_var_t doms_new[],
>   					   struct sched_domain_attr *dattr_new);
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index f87526edb2a4..f66b2aefdc04 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -954,10 +954,12 @@ static void dl_update_tasks_root_domain(struct cpuset *cs)
>   	css_task_iter_end(&it);
>   }
>   
> -static void dl_rebuild_rd_accounting(void)
> +void dl_rebuild_rd_accounting(void)
>   {
>   	struct cpuset *cs = NULL;
>   	struct cgroup_subsys_state *pos_css;
> +	int cpu;
> +	u64 cookie = ++dl_cookie;
>   
>   	lockdep_assert_held(&cpuset_mutex);
>   	lockdep_assert_cpus_held();
> @@ -965,11 +967,12 @@ static void dl_rebuild_rd_accounting(void)
>   
>   	rcu_read_lock();
>   
> -	/*
> -	 * Clear default root domain DL accounting, it will be computed again
> -	 * if a task belongs to it.
> -	 */
> -	dl_clear_root_domain(&def_root_domain);
> +	for_each_possible_cpu(cpu) {
> +		if (dl_bw_visited(cpu, cookie))
> +			continue;
> +
> +		dl_clear_root_domain_cpu(cpu);
> +	}
>   
>   	cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) {
>   
> @@ -996,7 +999,6 @@ partition_and_rebuild_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
>   {
>   	sched_domains_mutex_lock();
>   	partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);
> -	dl_rebuild_rd_accounting();
>   	sched_domains_mutex_unlock();
>   }
>   
> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
> index 339434271cba..17b040c92885 100644
> --- a/kernel/sched/deadline.c
> +++ b/kernel/sched/deadline.c
> @@ -166,7 +166,7 @@ static inline unsigned long dl_bw_capacity(int i)
>   	}
>   }
>   
> -static inline bool dl_bw_visited(int cpu, u64 cookie)
> +bool dl_bw_visited(int cpu, u64 cookie)
>   {
>   	struct root_domain *rd = cpu_rq(cpu)->rd;
>   
> @@ -207,7 +207,7 @@ static inline unsigned long dl_bw_capacity(int i)
>   	return SCHED_CAPACITY_SCALE;
>   }
>   
> -static inline bool dl_bw_visited(int cpu, u64 cookie)
> +bool dl_bw_visited(int cpu, u64 cookie)
>   {
>   	return false;
>   }
> @@ -2981,18 +2981,22 @@ void dl_clear_root_domain(struct root_domain *rd)
>   	rd->dl_bw.total_bw = 0;
>   
>   	/*
> -	 * dl_server bandwidth is only restored when CPUs are attached to root
> -	 * domains (after domains are created or CPUs moved back to the
> -	 * default root doamin).
> +	 * dl_servers are not tasks. Since dl_add_task_root_domanin ignores

s/dl_add_task_root_domanin/dl_add_task_root_domain

> +	 * them, we need to account for them here explicitly.
>   	 */
>   	for_each_cpu(i, rd->span) {
>   		struct sched_dl_entity *dl_se = &cpu_rq(i)->fair_server;
>   
>   		if (dl_server(dl_se) && cpu_active(i))
> -			rd->dl_bw.total_bw += dl_se->dl_bw;
> +			__dl_add(&rd->dl_bw, dl_se->dl_bw, dl_bw_cpus(i));
>   	}
>   }
>   
> +void dl_clear_root_domain_cpu(int cpu)
> +{
> +	dl_clear_root_domain(cpu_rq(cpu)->rd);
> +}
> +
>   #endif /* CONFIG_SMP */
>   
>   static void switched_from_dl(struct rq *rq, struct task_struct *p)
> 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();
>   }
>   
>   /*

Re: [PATCH v2 2/8] sched/topology: Wrappers for sched_domains_mutex

[Shrikanth Hegde]

Hi Juri.

On 3/6/25 19:40, Juri Lelli wrote:
> Create wrappers for sched_domains_mutex so that it can transparently be
> used on both CONFIG_SMP and !CONFIG_SMP, as some function will need to
> do.
> 
> Reported-by: Jon Hunter <jonathanh@nvidia.com>
> Fixes: 53916d5fd3c0 ("sched/deadline: Check bandwidth overflow earlier for hotplug")
> Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
> ---
> v1 -> v2: Remove wrappers for the !SMP case as all users are not defined
>            either in that case
> ---
>   include/linux/sched.h   |  2 ++
>   kernel/cgroup/cpuset.c  |  4 ++--
>   kernel/sched/core.c     |  4 ++--
>   kernel/sched/debug.c    |  8 ++++----
>   kernel/sched/topology.c | 12 ++++++++++--
>   5 files changed, 20 insertions(+), 10 deletions(-)
> 
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 9632e3318e0d..d5f8c161d852 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -383,6 +383,8 @@ enum uclamp_id {
>   extern struct root_domain def_root_domain;
>   extern struct mutex sched_domains_mutex;
>   #endif
> +extern void sched_domains_mutex_lock(void);
> +extern void sched_domains_mutex_unlock(void);
>   
>   struct sched_param {
>   	int sched_priority;
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index 0f910c828973..f87526edb2a4 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -994,10 +994,10 @@ static void
>   partition_and_rebuild_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
>   				    struct sched_domain_attr *dattr_new)
>   {
> -	mutex_lock(&sched_domains_mutex);
> +	sched_domains_mutex_lock();
>   	partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);
>   	dl_rebuild_rd_accounting();
> -	mutex_unlock(&sched_domains_mutex);
> +	sched_domains_mutex_unlock();
>   }
>   
>   /*
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 67189907214d..58593f4d09a1 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -8424,9 +8424,9 @@ void __init sched_init_smp(void)
>   	 * CPU masks are stable and all blatant races in the below code cannot
>   	 * happen.
>   	 */
> -	mutex_lock(&sched_domains_mutex);
> +	sched_domains_mutex_lock();
>   	sched_init_domains(cpu_active_mask);
> -	mutex_unlock(&sched_domains_mutex);
> +	sched_domains_mutex_unlock();
>   
>   	/* Move init over to a non-isolated CPU */
>   	if (set_cpus_allowed_ptr(current, housekeeping_cpumask(HK_TYPE_DOMAIN)) < 0)
> diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
> index ef047add7f9e..a0893a483d35 100644
> --- a/kernel/sched/debug.c
> +++ b/kernel/sched/debug.c
> @@ -292,7 +292,7 @@ static ssize_t sched_verbose_write(struct file *filp, const char __user *ubuf,
>   	bool orig;
>   
>   	cpus_read_lock();
> -	mutex_lock(&sched_domains_mutex);
> +	sched_domains_mutex_lock();
>   
>   	orig = sched_debug_verbose;
>   	result = debugfs_write_file_bool(filp, ubuf, cnt, ppos);
> @@ -304,7 +304,7 @@ static ssize_t sched_verbose_write(struct file *filp, const char __user *ubuf,
>   		sd_dentry = NULL;
>   	}
>   
> -	mutex_unlock(&sched_domains_mutex);
> +	sched_domains_mutex_unlock();
>   	cpus_read_unlock();
>   
>   	return result;
> @@ -515,9 +515,9 @@ static __init int sched_init_debug(void)
>   	debugfs_create_u32("migration_cost_ns", 0644, debugfs_sched, &sysctl_sched_migration_cost);
>   	debugfs_create_u32("nr_migrate", 0644, debugfs_sched, &sysctl_sched_nr_migrate);
>   
> -	mutex_lock(&sched_domains_mutex);
> +	sched_domains_mutex_lock();
>   	update_sched_domain_debugfs();
> -	mutex_unlock(&sched_domains_mutex);
> +	sched_domains_mutex_unlock();
>   #endif
>   
>   #ifdef CONFIG_NUMA_BALANCING
> diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
> index c49aea8c1025..296ff2acfd32 100644
> --- a/kernel/sched/topology.c
> +++ b/kernel/sched/topology.c
> @@ -6,6 +6,14 @@
>   #include <linux/bsearch.h>
>   
>   DEFINE_MUTEX(sched_domains_mutex);
> +void sched_domains_mutex_lock(void)
> +{
> +	mutex_lock(&sched_domains_mutex);
> +}
> +void sched_domains_mutex_unlock(void)
> +{
> +	mutex_unlock(&sched_domains_mutex);
> +}
>   
>   /* Protected by sched_domains_mutex: */
>   static cpumask_var_t sched_domains_tmpmask;
> @@ -2791,7 +2799,7 @@ void partition_sched_domains_locked(int ndoms_new, cpumask_var_t doms_new[],
>   void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
>   			     struct sched_domain_attr *dattr_new)
>   {
> -	mutex_lock(&sched_domains_mutex);
> +	sched_domains_mutex_lock();
>   	partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);
> -	mutex_unlock(&sched_domains_mutex);
> +	sched_domains_mutex_unlock();
>   }

Maybe sched_domains_mutex can be static since its only used in topology.c ?

Other than the above
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>

Re: [PATCH v2 4/8] sched/deadline: Rebuild root domain accounting after every update

[Shrikanth Hegde]

On 3/6/25 19:40, Juri Lelli wrote:
> Rebuilding of root domains accounting information (total_bw) is
> currently broken on some cases, e.g. suspend/resume on aarch64. Problem
> is that the way we keep track of domain changes and try to add bandwidth
> back is convoluted and fragile.
> 
> Fix it by simplify things by making sure bandwidth accounting is cleared
> and completely restored after root domains changes (after root domains
> are again stable).
> 
> Reported-by: Jon Hunter <jonathanh@nvidia.com>
> Fixes: 53916d5fd3c0 ("sched/deadline: Check bandwidth overflow earlier for hotplug")
> Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
> ---
>   include/linux/sched/deadline.h |  4 ++++
>   include/linux/sched/topology.h |  2 ++
>   kernel/cgroup/cpuset.c         | 16 +++++++++-------
>   kernel/sched/deadline.c        | 16 ++++++++++------
>   kernel/sched/topology.c        |  1 +
>   5 files changed, 26 insertions(+), 13 deletions(-)
> 
> diff --git a/include/linux/sched/deadline.h b/include/linux/sched/deadline.h
> index 6ec578600b24..a780068aa1a5 100644
> --- a/include/linux/sched/deadline.h
> +++ b/include/linux/sched/deadline.h
> @@ -34,6 +34,10 @@ static inline bool dl_time_before(u64 a, u64 b)
>   struct root_domain;
>   extern void dl_add_task_root_domain(struct task_struct *p);
>   extern void dl_clear_root_domain(struct root_domain *rd);
> +extern void dl_clear_root_domain_cpu(int cpu);
> +
> +extern u64 dl_cookie;
> +extern bool dl_bw_visited(int cpu, u64 gen);
>   
>   #endif /* CONFIG_SMP */
>   
> diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h
> index 7f3dbafe1817..1622232bd08b 100644
> --- a/include/linux/sched/topology.h
> +++ b/include/linux/sched/topology.h
> @@ -166,6 +166,8 @@ static inline struct cpumask *sched_domain_span(struct sched_domain *sd)
>   	return to_cpumask(sd->span);
>   }
>   
> +extern void dl_rebuild_rd_accounting(void);
> +
>   extern void partition_sched_domains_locked(int ndoms_new,
>   					   cpumask_var_t doms_new[],
>   					   struct sched_domain_attr *dattr_new);
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index f87526edb2a4..f66b2aefdc04 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -954,10 +954,12 @@ static void dl_update_tasks_root_domain(struct cpuset *cs)
>   	css_task_iter_end(&it);
>   }
>   
> -static void dl_rebuild_rd_accounting(void)
> +void dl_rebuild_rd_accounting(void)
>   {
>   	struct cpuset *cs = NULL;
>   	struct cgroup_subsys_state *pos_css;
> +	int cpu;
> +	u64 cookie = ++dl_cookie;
>   
>   	lockdep_assert_held(&cpuset_mutex);
>   	lockdep_assert_cpus_held();
> @@ -965,11 +967,12 @@ static void dl_rebuild_rd_accounting(void)
>   
>   	rcu_read_lock();
>   
> -	/*
> -	 * Clear default root domain DL accounting, it will be computed again
> -	 * if a task belongs to it.
> -	 */
> -	dl_clear_root_domain(&def_root_domain);
> +	for_each_possible_cpu(cpu) {
> +		if (dl_bw_visited(cpu, cookie))
> +			continue;
> +
> +		dl_clear_root_domain_cpu(cpu);
> +	}
>   

This will clear all possible root domains bandwidth and rebuild it.

For an online CPUs, the fair server bandwidth is added i think in 
rq_attach_root. But for an offline CPUs the sched domains wont be 
rebuilt. It may not be an issue. but the def_root_domain's bw may be 
different afterwords. no?

>   	cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) {
>   
> @@ -996,7 +999,6 @@ partition_and_rebuild_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
>   {
>   	sched_domains_mutex_lock();
>   	partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);
> -	dl_rebuild_rd_accounting();
>   	sched_domains_mutex_unlock();
>   }
>   
> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
> index 339434271cba..17b040c92885 100644
> --- a/kernel/sched/deadline.c
> +++ b/kernel/sched/deadline.c
> @@ -166,7 +166,7 @@ static inline unsigned long dl_bw_capacity(int i)
>   	}
>   }
>   
> -static inline bool dl_bw_visited(int cpu, u64 cookie)
> +bool dl_bw_visited(int cpu, u64 cookie)
>   {
>   	struct root_domain *rd = cpu_rq(cpu)->rd;
>   
> @@ -207,7 +207,7 @@ static inline unsigned long dl_bw_capacity(int i)
>   	return SCHED_CAPACITY_SCALE;
>   }
>   
> -static inline bool dl_bw_visited(int cpu, u64 cookie)
> +bool dl_bw_visited(int cpu, u64 cookie)
>   {
>   	return false;
>   }
> @@ -2981,18 +2981,22 @@ void dl_clear_root_domain(struct root_domain *rd)
>   	rd->dl_bw.total_bw = 0;
>   
>   	/*
> -	 * dl_server bandwidth is only restored when CPUs are attached to root
> -	 * domains (after domains are created or CPUs moved back to the
> -	 * default root doamin).
> +	 * dl_servers are not tasks. Since dl_add_task_root_domanin ignores
> +	 * them, we need to account for them here explicitly.
>   	 */
>   	for_each_cpu(i, rd->span) {
>   		struct sched_dl_entity *dl_se = &cpu_rq(i)->fair_server;
>   
>   		if (dl_server(dl_se) && cpu_active(i))
> -			rd->dl_bw.total_bw += dl_se->dl_bw;
> +			__dl_add(&rd->dl_bw, dl_se->dl_bw, dl_bw_cpus(i));
>   	}
>   }
>   
> +void dl_clear_root_domain_cpu(int cpu)
> +{
> +	dl_clear_root_domain(cpu_rq(cpu)->rd);
> +}
> +
>   #endif /* CONFIG_SMP */
>   
>   static void switched_from_dl(struct rq *rq, struct task_struct *p)
> 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();
>   }
>   
>   /*

Re: [PATCH v2 6/8] cgroup/cpuset: Remove partition_and_rebuild_sched_domains

[Shrikanth Hegde]

On 3/6/25 19:40, Juri Lelli wrote:
> partition_and_rebuild_sched_domains() and partition_sched_domains() are
> now equivalent.
> 
> Remove the former as a nice clean up.
> 
> Suggested-by: Waiman Long <llong@redhat.com>
> Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
> ---
>   kernel/cgroup/cpuset.c | 11 +----------
>   1 file changed, 1 insertion(+), 10 deletions(-)
> 
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index f66b2aefdc04..7995cd58a01b 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -993,15 +993,6 @@ void dl_rebuild_rd_accounting(void)
>   	rcu_read_unlock();
>   }
>   
> -static void
> -partition_and_rebuild_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
> -				    struct sched_domain_attr *dattr_new)
> -{
> -	sched_domains_mutex_lock();
> -	partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);
> -	sched_domains_mutex_unlock();
> -}
> -
>   /*
>    * Rebuild scheduler domains.
>    *
> @@ -1063,7 +1054,7 @@ void rebuild_sched_domains_locked(void)
>   	ndoms = generate_sched_domains(&doms, &attr);
>   
>   	/* Have scheduler rebuild the domains */
> -	partition_and_rebuild_sched_domains(ndoms, doms, attr);
> +	partition_sched_domains(ndoms, doms, attr);
>   }
>   #else /* !CONFIG_SMP */
>   void rebuild_sched_domains_locked(void)

This makes sense.

Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>

Re: [PATCH v2 2/8] sched/topology: Wrappers for sched_domains_mutex

[Juri Lelli]

Hi,

Thanks for the overall review!

On 07/03/25 12:04, Shrikanth Hegde wrote:
> Hi Juri.
> 
> On 3/6/25 19:40, Juri Lelli wrote:
> > Create wrappers for sched_domains_mutex so that it can transparently be
> > used on both CONFIG_SMP and !CONFIG_SMP, as some function will need to
> > do.

...

> Maybe sched_domains_mutex can be static since its only used in topology.c ?

We have a lockdep_assert in cpuset.c, don't we? We can create another
wrapper for that, but I am not sure it is going to be cleaner.

Thanks,
Juri

Re: [PATCH v2 3/8] sched/deadline: Generalize unique visiting of root domains

[Juri Lelli]

On 07/03/25 11:06, Shrikanth Hegde wrote:
> 
> 
> On 3/6/25 19:40, Juri Lelli wrote:
> > Bandwidth checks and updates that work on root domains currently employ
> > a cookie mechanism for efficiency. This mechanism is very much tied to
> > when root domains are first created and initialized.
> > 
> > Generalize the cookie mechanism so that it can be used also later at
> > runtime while updating root domains. Also, additionally guard it with
> > sched_domains_mutex, since domains need to be stable while updating them
> > (and it will be required for further dynamic changes).
> > 
> > Reported-by: Jon Hunter <jonathanh@nvidia.com>
> > Fixes: 53916d5fd3c0 ("sched/deadline: Check bandwidth overflow earlier for hotplug")
> > Signed-off-by: Juri Lelli <juri.lelli@redhat.com>

...

> > @@ -3192,7 +3195,7 @@ int sched_dl_global_validate(void)
> >   	for_each_possible_cpu(cpu) {
> 
> This has been changed in 14672f059d83f591afb2ee1fff56858efe055e5a to online
> CPUs. So patch didn't apply cleanly to me.
> 

I based the set on Linus' tree (base commit in the cover letter) as it
is modifying both sched and cgroup bits. Your fix hasn't yet be merged
into Linus' I believe.

Thanks,
Juri

Re: [PATCH v2 4/8] sched/deadline: Rebuild root domain accounting after every update

[Juri Lelli]

On 07/03/25 13:02, Shrikanth Hegde wrote:
> 
> 
> On 3/6/25 19:40, Juri Lelli wrote:
> > Rebuilding of root domains accounting information (total_bw) is
> > currently broken on some cases, e.g. suspend/resume on aarch64. Problem
> > is that the way we keep track of domain changes and try to add bandwidth
> > back is convoluted and fragile.
> > 
> > Fix it by simplify things by making sure bandwidth accounting is cleared
> > and completely restored after root domains changes (after root domains
> > are again stable).
> > 
> > Reported-by: Jon Hunter <jonathanh@nvidia.com>
> > Fixes: 53916d5fd3c0 ("sched/deadline: Check bandwidth overflow earlier for hotplug")
> > Signed-off-by: Juri Lelli <juri.lelli@redhat.com>

...

> > @@ -965,11 +967,12 @@ static void dl_rebuild_rd_accounting(void)
> >   	rcu_read_lock();
> > -	/*
> > -	 * Clear default root domain DL accounting, it will be computed again
> > -	 * if a task belongs to it.
> > -	 */
> > -	dl_clear_root_domain(&def_root_domain);
> > +	for_each_possible_cpu(cpu) {
> > +		if (dl_bw_visited(cpu, cookie))
> > +			continue;
> > +
> > +		dl_clear_root_domain_cpu(cpu);
> > +	}
> 
> This will clear all possible root domains bandwidth and rebuild it.
> 
> For an online CPUs, the fair server bandwidth is added i think in
> rq_attach_root. But for an offline CPUs the sched domains wont be rebuilt.
> It may not be an issue. but the def_root_domain's bw may be different
> afterwords. no?

dl_clear_root_domain() actually adds DL servers contribution back on
their domains (dynamic and def) and we want to keep offline CPUs DL
server contribution not accounted for until they come back online and
the domains are rebuilt.

Thanks,
Juri

Re: [PATCH v2 2/8] sched/topology: Wrappers for sched_domains_mutex

[Shrikanth Hegde]

On 3/7/25 14:23, Juri Lelli wrote:
> Hi,
> 
> Thanks for the overall review!
> 
> On 07/03/25 12:04, Shrikanth Hegde wrote:
>> Hi Juri.
>>
>> On 3/6/25 19:40, Juri Lelli wrote:
>>> Create wrappers for sched_domains_mutex so that it can transparently be
>>> used on both CONFIG_SMP and !CONFIG_SMP, as some function will need to
>>> do.
> 
> ...
> 
>> Maybe sched_domains_mutex can be static since its only used in topology.c ?
> 
> We have a lockdep_assert in cpuset.c, don't we? We can create another
> wrapper for that, but I am not sure it is going to be cleaner.

Ok. Sorry, my bad. I searched only in kernel/sched. You can ignore this 
comment.

> 
> Thanks,
> Juri
> 

Re: [PATCH v2 4/8] sched/deadline: Rebuild root domain accounting after every update

[Juri Lelli]

On 07/03/25 12:03, Shrikanth Hegde wrote:
> Hi Juri.
> 
> On 3/6/25 19:40, Juri Lelli wrote:
> > Rebuilding of root domains accounting information (total_bw) is
> > currently broken on some cases, e.g. suspend/resume on aarch64. Problem
> > is that the way we keep track of domain changes and try to add bandwidth
> > back is convoluted and fragile.
> > 
> > Fix it by simplify things by making sure bandwidth accounting is cleared
> > and completely restored after root domains changes (after root domains
> > are again stable).
> > 
> > Reported-by: Jon Hunter <jonathanh@nvidia.com>
> > Fixes: 53916d5fd3c0 ("sched/deadline: Check bandwidth overflow earlier for hotplug")
> > Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
> > ---
> >   include/linux/sched/deadline.h |  4 ++++
> >   include/linux/sched/topology.h |  2 ++
> >   kernel/cgroup/cpuset.c         | 16 +++++++++-------
> >   kernel/sched/deadline.c        | 16 ++++++++++------
> >   kernel/sched/topology.c        |  1 +
> >   5 files changed, 26 insertions(+), 13 deletions(-)
> > 
> > diff --git a/include/linux/sched/deadline.h b/include/linux/sched/deadline.h
> > index 6ec578600b24..a780068aa1a5 100644
> > --- a/include/linux/sched/deadline.h
> > +++ b/include/linux/sched/deadline.h
> > @@ -34,6 +34,10 @@ static inline bool dl_time_before(u64 a, u64 b)
> >   struct root_domain;
> >   extern void dl_add_task_root_domain(struct task_struct *p);
> >   extern void dl_clear_root_domain(struct root_domain *rd);
> > +extern void dl_clear_root_domain_cpu(int cpu);
> > +
> > +extern u64 dl_cookie;
> > +extern bool dl_bw_visited(int cpu, u64 gen);
> 
> Is this needed? There is same declaration outside of CONFIG_SMP done in
> patch 3/8.

Nope. Good catch.

Thanks,
Juri

Re: [PATCH v2 0/8] Fix SCHED_DEADLINE bandwidth accounting during suspend

[Jon Hunter]

Hi Juri,

On 06/03/2025 14:10, Juri Lelli wrote:
> Hello!
> 
> Jon reported [1] a suspend regression on a Tegra board configured to
> boot with isolcpus and bisected it to commit 53916d5fd3c0
> ("sched/deadline: Check bandwidth overflow earlier for hotplug").
> 
> Root cause analysis pointed out that we are currently failing to
> correctly clear and restore bandwidth accounting on root domains after
> changes that initiate from partition_sched_domains(), as it is the case
> for suspend operations on that board.
> 
> This is v2 [2] of the proposed approach to fix the issue. With respect
> to v1, the following implements the approach by:
> 
> - 01: filter out DEADLINE special tasks
> - 02: preparatory wrappers to be able to grab sched_domains_mutex on
>        UP (remove !SMP wrappers - Waiman)
> - 03: generalize unique visiting of root domains so that we can
>        re-use the mechanism elsewhere
> - 04: the bulk of the approach, clean and rebuild after changes
> - 05: clean up a now redundant call
> - 06: remove partition_and_rebuild_sched_domains() (Waiman)
> - 07: stop exposing partition_sched_domains_locked (Waiman)
> 
> Please test and review. The set is also available at


Tested-by: Jon Hunter <jonathanh@nvidia.com>

Thanks!
Jon

-- 
nvpublic

Re: [PATCH v2 2/8] sched/topology: Wrappers for sched_domains_mutex

[Waiman Long]

On 3/6/25 9:10 AM, Juri Lelli wrote:
> Create wrappers for sched_domains_mutex so that it can transparently be
> used on both CONFIG_SMP and !CONFIG_SMP, as some function will need to
> do.
>
> Reported-by: Jon Hunter <jonathanh@nvidia.com>
> Fixes: 53916d5fd3c0 ("sched/deadline: Check bandwidth overflow earlier for hotplug")
> Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
> ---
> v1 -> v2: Remove wrappers for the !SMP case as all users are not defined
>            either in that case
> ---
>   include/linux/sched.h   |  2 ++
>   kernel/cgroup/cpuset.c  |  4 ++--
>   kernel/sched/core.c     |  4 ++--
>   kernel/sched/debug.c    |  8 ++++----
>   kernel/sched/topology.c | 12 ++++++++++--
>   5 files changed, 20 insertions(+), 10 deletions(-)
>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 9632e3318e0d..d5f8c161d852 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -383,6 +383,8 @@ enum uclamp_id {
>   extern struct root_domain def_root_domain;
>   extern struct mutex sched_domains_mutex;
>   #endif
> +extern void sched_domains_mutex_lock(void);
> +extern void sched_domains_mutex_unlock(void);

As discussed in the other thread, move the 
sched_domains_mutex_{lock/unlock}{} inside the "#if CONFIG_SMP" block 
and define the else part so that it can be used in code block that will 
also be compiled in the !CONFIG_SMP case.

Other than that, the rest looks good to me.

Cheers,
Longman

Re: [PATCH v2 6/8] cgroup/cpuset: Remove partition_and_rebuild_sched_domains

[Waiman Long]

On 3/6/25 9:10 AM, Juri Lelli wrote:
> partition_and_rebuild_sched_domains() and partition_sched_domains() are
> now equivalent.
>
> Remove the former as a nice clean up.
>
> Suggested-by: Waiman Long <llong@redhat.com>
> Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
> ---
>   kernel/cgroup/cpuset.c | 11 +----------
>   1 file changed, 1 insertion(+), 10 deletions(-)
>
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index f66b2aefdc04..7995cd58a01b 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -993,15 +993,6 @@ void dl_rebuild_rd_accounting(void)
>   	rcu_read_unlock();
>   }
>   
> -static void
> -partition_and_rebuild_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
> -				    struct sched_domain_attr *dattr_new)
> -{
> -	sched_domains_mutex_lock();
> -	partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);
> -	sched_domains_mutex_unlock();
> -}
> -
>   /*
>    * Rebuild scheduler domains.
>    *
> @@ -1063,7 +1054,7 @@ void rebuild_sched_domains_locked(void)
>   	ndoms = generate_sched_domains(&doms, &attr);
>   
>   	/* Have scheduler rebuild the domains */
> -	partition_and_rebuild_sched_domains(ndoms, doms, attr);
> +	partition_sched_domains(ndoms, doms, attr);
>   }
>   #else /* !CONFIG_SMP */
>   void rebuild_sched_domains_locked(void)
Reviewed-by: Waiman Long <llong@redhat.com>

Re: [PATCH v2 2/8] sched/topology: Wrappers for sched_domains_mutex

[Juri Lelli]

On 07/03/25 10:11, Waiman Long wrote:
> On 3/6/25 9:10 AM, Juri Lelli wrote:
> > Create wrappers for sched_domains_mutex so that it can transparently be
> > used on both CONFIG_SMP and !CONFIG_SMP, as some function will need to
> > do.
> > 
> > Reported-by: Jon Hunter <jonathanh@nvidia.com>
> > Fixes: 53916d5fd3c0 ("sched/deadline: Check bandwidth overflow earlier for hotplug")
> > Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
> > ---
> > v1 -> v2: Remove wrappers for the !SMP case as all users are not defined
> >            either in that case
> > ---
> >   include/linux/sched.h   |  2 ++
> >   kernel/cgroup/cpuset.c  |  4 ++--
> >   kernel/sched/core.c     |  4 ++--
> >   kernel/sched/debug.c    |  8 ++++----
> >   kernel/sched/topology.c | 12 ++++++++++--
> >   5 files changed, 20 insertions(+), 10 deletions(-)
> > 
> > diff --git a/include/linux/sched.h b/include/linux/sched.h
> > index 9632e3318e0d..d5f8c161d852 100644
> > --- a/include/linux/sched.h
> > +++ b/include/linux/sched.h
> > @@ -383,6 +383,8 @@ enum uclamp_id {
> >   extern struct root_domain def_root_domain;
> >   extern struct mutex sched_domains_mutex;
> >   #endif
> > +extern void sched_domains_mutex_lock(void);
> > +extern void sched_domains_mutex_unlock(void);
> 
> As discussed in the other thread, move the
> sched_domains_mutex_{lock/unlock}{} inside the "#if CONFIG_SMP" block and
> define the else part so that it can be used in code block that will also be
> compiled in the !CONFIG_SMP case.

Ack. 

> Other than that, the rest looks good to me.

Thanks! I will be sending out a v3 early next week (waiting a few more
hours in case anyone spots something else that needs rework).

Best,
Juri

Re: [PATCH v2 6/8] cgroup/cpuset: Remove partition_and_rebuild_sched_domains

[Waiman Long]

On 3/6/25 9:10 AM, Juri Lelli wrote:
> partition_and_rebuild_sched_domains() and partition_sched_domains() are
> now equivalent.
>
> Remove the former as a nice clean up.
>
> Suggested-by: Waiman Long <llong@redhat.com>
> Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
> ---
>   kernel/cgroup/cpuset.c | 11 +----------
>   1 file changed, 1 insertion(+), 10 deletions(-)
>
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index f66b2aefdc04..7995cd58a01b 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -993,15 +993,6 @@ void dl_rebuild_rd_accounting(void)
>   	rcu_read_unlock();
>   }
>   
> -static void
> -partition_and_rebuild_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
> -				    struct sched_domain_attr *dattr_new)
> -{
> -	sched_domains_mutex_lock();
> -	partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);
> -	sched_domains_mutex_unlock();
> -}
> -
>   /*
>    * Rebuild scheduler domains.
>    *
> @@ -1063,7 +1054,7 @@ void rebuild_sched_domains_locked(void)
>   	ndoms = generate_sched_domains(&doms, &attr);
>   
>   	/* Have scheduler rebuild the domains */
> -	partition_and_rebuild_sched_domains(ndoms, doms, attr);
> +	partition_sched_domains(ndoms, doms, attr);
>   }
>   #else /* !CONFIG_SMP */
>   void rebuild_sched_domains_locked(void)
Reviewed-by: Waiman Long <llong@redhat.com>

Re: [PATCH v2 0/8] Fix SCHED_DEADLINE bandwidth accounting during suspend

[Juri Lelli]

Hi Jon,

On 07/03/25 11:40, Jon Hunter wrote:
> Hi Juri,
> 
> On 06/03/2025 14:10, Juri Lelli wrote:
> > Hello!
> > 
> > Jon reported [1] a suspend regression on a Tegra board configured to
> > boot with isolcpus and bisected it to commit 53916d5fd3c0
> > ("sched/deadline: Check bandwidth overflow earlier for hotplug").
> > 
> > Root cause analysis pointed out that we are currently failing to
> > correctly clear and restore bandwidth accounting on root domains after
> > changes that initiate from partition_sched_domains(), as it is the case
> > for suspend operations on that board.
> > 
> > This is v2 [2] of the proposed approach to fix the issue. With respect
> > to v1, the following implements the approach by:
> > 
> > - 01: filter out DEADLINE special tasks
> > - 02: preparatory wrappers to be able to grab sched_domains_mutex on
> >        UP (remove !SMP wrappers - Waiman)
> > - 03: generalize unique visiting of root domains so that we can
> >        re-use the mechanism elsewhere
> > - 04: the bulk of the approach, clean and rebuild after changes
> > - 05: clean up a now redundant call
> > - 06: remove partition_and_rebuild_sched_domains() (Waiman)
> > - 07: stop exposing partition_sched_domains_locked (Waiman)
> > 
> > Please test and review. The set is also available at
> 
> 
> Tested-by: Jon Hunter <jonathanh@nvidia.com>

Thanks!

Best,
Juri

Re: [PATCH v2 8/8] include/{topology,cpuset}: Move dl_rebuild_rd_accounting to cpuset.h

[Waiman Long]

On 3/6/25 9:10 AM, Juri Lelli wrote:
> dl_rebuild_rd_accounting() is defined in cpuset.c, so it makes more
> sense to move related declarations to cpuset.h.
>
> Implement the move.
>
> Suggested-by: Waiman Long <llong@redhat.com>
> Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
> ---
>   include/linux/cpuset.h         | 5 +++++
>   include/linux/sched/topology.h | 2 --
>   2 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
> index 835e7b793f6a..c414daa7d503 100644
> --- a/include/linux/cpuset.h
> +++ b/include/linux/cpuset.h
> @@ -125,6 +125,7 @@ static inline int cpuset_do_page_mem_spread(void)
>   
>   extern bool current_cpuset_is_being_rebound(void);
>   
> +extern void dl_rebuild_rd_accounting(void);
>   extern void rebuild_sched_domains(void);
>   
>   extern void cpuset_print_current_mems_allowed(void);
> @@ -259,6 +260,10 @@ static inline bool current_cpuset_is_being_rebound(void)
>   	return false;
>   }
>   
> +static inline void dl_rebuild_rd_accounting(void)
> +{
> +}
> +
>   static inline void rebuild_sched_domains(void)
>   {
>   	partition_sched_domains(1, NULL, NULL);
> diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h
> index 96e69bfc3c8a..51f7b8169515 100644
> --- a/include/linux/sched/topology.h
> +++ b/include/linux/sched/topology.h
> @@ -166,8 +166,6 @@ static inline struct cpumask *sched_domain_span(struct sched_domain *sd)
>   	return to_cpumask(sd->span);
>   }
>   
> -extern void dl_rebuild_rd_accounting(void);
> -
>   extern void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
>   				    struct sched_domain_attr *dattr_new);
>   
Reviewed-by: Waiman Long <llong@redhat.com>

Re: [PATCH v2 2/8] sched/topology: Wrappers for sched_domains_mutex

[Waiman Long]

On 3/7/25 10:11 AM, Waiman Long wrote:
> On 3/6/25 9:10 AM, Juri Lelli wrote:
>> Create wrappers for sched_domains_mutex so that it can transparently be
>> used on both CONFIG_SMP and !CONFIG_SMP, as some function will need to
>> do.
>>
>> Reported-by: Jon Hunter <jonathanh@nvidia.com>
>> Fixes: 53916d5fd3c0 ("sched/deadline: Check bandwidth overflow 
>> earlier for hotplug")
>> Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
>> ---
>> v1 -> v2: Remove wrappers for the !SMP case as all users are not defined
>>            either in that case
>> ---
>>   include/linux/sched.h   |  2 ++
>>   kernel/cgroup/cpuset.c  |  4 ++--
>>   kernel/sched/core.c     |  4 ++--
>>   kernel/sched/debug.c    |  8 ++++----
>>   kernel/sched/topology.c | 12 ++++++++++--
>>   5 files changed, 20 insertions(+), 10 deletions(-)
>>
>> diff --git a/include/linux/sched.h b/include/linux/sched.h
>> index 9632e3318e0d..d5f8c161d852 100644
>> --- a/include/linux/sched.h
>> +++ b/include/linux/sched.h
>> @@ -383,6 +383,8 @@ enum uclamp_id {
>>   extern struct root_domain def_root_domain;
>>   extern struct mutex sched_domains_mutex;
>>   #endif
>> +extern void sched_domains_mutex_lock(void);
>> +extern void sched_domains_mutex_unlock(void);
>
> As discussed in the other thread, move the 
> sched_domains_mutex_{lock/unlock}{} inside the "#if CONFIG_SMP" block 
> and define the else part so that it can be used in code block that 
> will also be compiled in the !CONFIG_SMP case.
>
> Other than that, the rest looks good to me.

Actually, you can also remove sched_domains_mutex from the header and 
make it static as it is no longer directly accessed.

Cheers,
Longman

Re: [PATCH v2 2/8] sched/topology: Wrappers for sched_domains_mutex

[Juri Lelli]

On 07/03/25 10:19, Waiman Long wrote:
> 
> On 3/7/25 10:11 AM, Waiman Long wrote:
> > On 3/6/25 9:10 AM, Juri Lelli wrote:
> > > Create wrappers for sched_domains_mutex so that it can transparently be
> > > used on both CONFIG_SMP and !CONFIG_SMP, as some function will need to
> > > do.
> > > 
> > > Reported-by: Jon Hunter <jonathanh@nvidia.com>
> > > Fixes: 53916d5fd3c0 ("sched/deadline: Check bandwidth overflow
> > > earlier for hotplug")
> > > Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
> > > ---
> > > v1 -> v2: Remove wrappers for the !SMP case as all users are not defined
> > >            either in that case
> > > ---
> > >   include/linux/sched.h   |  2 ++
> > >   kernel/cgroup/cpuset.c  |  4 ++--
> > >   kernel/sched/core.c     |  4 ++--
> > >   kernel/sched/debug.c    |  8 ++++----
> > >   kernel/sched/topology.c | 12 ++++++++++--
> > >   5 files changed, 20 insertions(+), 10 deletions(-)
> > > 
> > > diff --git a/include/linux/sched.h b/include/linux/sched.h
> > > index 9632e3318e0d..d5f8c161d852 100644
> > > --- a/include/linux/sched.h
> > > +++ b/include/linux/sched.h
> > > @@ -383,6 +383,8 @@ enum uclamp_id {
> > >   extern struct root_domain def_root_domain;
> > >   extern struct mutex sched_domains_mutex;
> > >   #endif
> > > +extern void sched_domains_mutex_lock(void);
> > > +extern void sched_domains_mutex_unlock(void);
> > 
> > As discussed in the other thread, move the
> > sched_domains_mutex_{lock/unlock}{} inside the "#if CONFIG_SMP" block
> > and define the else part so that it can be used in code block that will
> > also be compiled in the !CONFIG_SMP case.
> > 
> > Other than that, the rest looks good to me.
> 
> Actually, you can also remove sched_domains_mutex from the header and make
> it static as it is no longer directly accessed.

Apart from a lockdep_assert_held() in cpuset.c, no? Guess I can create a
wrapper for that, but is it really better?

Thanks,
Juri

Re: [PATCH v2 2/8] sched/topology: Wrappers for sched_domains_mutex

[Waiman Long]

On 3/7/25 10:59 AM, Juri Lelli wrote:
> On 07/03/25 10:19, Waiman Long wrote:
>> On 3/7/25 10:11 AM, Waiman Long wrote:
>>> On 3/6/25 9:10 AM, Juri Lelli wrote:
>>>> Create wrappers for sched_domains_mutex so that it can transparently be
>>>> used on both CONFIG_SMP and !CONFIG_SMP, as some function will need to
>>>> do.
>>>>
>>>> Reported-by: Jon Hunter <jonathanh@nvidia.com>
>>>> Fixes: 53916d5fd3c0 ("sched/deadline: Check bandwidth overflow
>>>> earlier for hotplug")
>>>> Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
>>>> ---
>>>> v1 -> v2: Remove wrappers for the !SMP case as all users are not defined
>>>>             either in that case
>>>> ---
>>>>    include/linux/sched.h   |  2 ++
>>>>    kernel/cgroup/cpuset.c  |  4 ++--
>>>>    kernel/sched/core.c     |  4 ++--
>>>>    kernel/sched/debug.c    |  8 ++++----
>>>>    kernel/sched/topology.c | 12 ++++++++++--
>>>>    5 files changed, 20 insertions(+), 10 deletions(-)
>>>>
>>>> diff --git a/include/linux/sched.h b/include/linux/sched.h
>>>> index 9632e3318e0d..d5f8c161d852 100644
>>>> --- a/include/linux/sched.h
>>>> +++ b/include/linux/sched.h
>>>> @@ -383,6 +383,8 @@ enum uclamp_id {
>>>>    extern struct root_domain def_root_domain;
>>>>    extern struct mutex sched_domains_mutex;
>>>>    #endif
>>>> +extern void sched_domains_mutex_lock(void);
>>>> +extern void sched_domains_mutex_unlock(void);
>>> As discussed in the other thread, move the
>>> sched_domains_mutex_{lock/unlock}{} inside the "#if CONFIG_SMP" block
>>> and define the else part so that it can be used in code block that will
>>> also be compiled in the !CONFIG_SMP case.
>>>
>>> Other than that, the rest looks good to me.
>> Actually, you can also remove sched_domains_mutex from the header and make
>> it static as it is no longer directly accessed.
> Apart from a lockdep_assert_held() in cpuset.c, no? Guess I can create a
> wrapper for that, but is it really better?

I forgot about that. Please ignore this comment.

Thanks,
Longman

Re: [PATCH v2 0/8] Fix SCHED_DEADLINE bandwidth accounting during suspend

[Waiman Long]

On 3/6/25 9:10 AM, Juri Lelli wrote:
> Hello!
>
> Jon reported [1] a suspend regression on a Tegra board configured to
> boot with isolcpus and bisected it to commit 53916d5fd3c0
> ("sched/deadline: Check bandwidth overflow earlier for hotplug").
>
> Root cause analysis pointed out that we are currently failing to
> correctly clear and restore bandwidth accounting on root domains after
> changes that initiate from partition_sched_domains(), as it is the case
> for suspend operations on that board.
>
> This is v2 [2] of the proposed approach to fix the issue. With respect
> to v1, the following implements the approach by:
>
> - 01: filter out DEADLINE special tasks
> - 02: preparatory wrappers to be able to grab sched_domains_mutex on
>        UP (remove !SMP wrappers - Waiman)
> - 03: generalize unique visiting of root domains so that we can
>        re-use the mechanism elsewhere
> - 04: the bulk of the approach, clean and rebuild after changes
> - 05: clean up a now redundant call
> - 06: remove partition_and_rebuild_sched_domains() (Waiman)
> - 07: stop exposing partition_sched_domains_locked (Waiman)
>
> Please test and review. The set is also available at
>
> git@github.com:jlelli/linux.git upstream/deadline/domains-suspend
>
> Best,
> Juri
>
> 1 - https://lore.kernel.org/lkml/ba51a43f-796d-4b79-808a-b8185905638a@nvidia.com/
> 2 - v1 https://lore.kernel.org/lkml/20250304084045.62554-1-juri.lelli@redhat.com
>
> Juri Lelli (8):
>    sched/deadline: Ignore special tasks when rebuilding domains
>    sched/topology: Wrappers for sched_domains_mutex
>    sched/deadline: Generalize unique visiting of root domains
>    sched/deadline: Rebuild root domain accounting after every update
>    sched/topology: Remove redundant dl_clear_root_domain call
>    cgroup/cpuset: Remove partition_and_rebuild_sched_domains
>    sched/topology: Stop exposing partition_sched_domains_locked
>    include/{topology,cpuset}: Move dl_rebuild_rd_accounting to cpuset.h
>
>   include/linux/cpuset.h         |  5 +++++
>   include/linux/sched.h          |  2 ++
>   include/linux/sched/deadline.h |  7 +++++++
>   include/linux/sched/topology.h | 10 ---------
>   kernel/cgroup/cpuset.c         | 27 +++++++++----------------
>   kernel/sched/core.c            |  4 ++--
>   kernel/sched/deadline.c        | 37 ++++++++++++++++++++--------------
>   kernel/sched/debug.c           |  8 ++++----
>   kernel/sched/rt.c              |  2 ++
>   kernel/sched/sched.h           |  2 +-
>   kernel/sched/topology.c        | 32 +++++++++++++----------------
>   11 files changed, 69 insertions(+), 67 deletions(-)
>
>
> base-commit: 48a5eed9ad584315c30ed35204510536235ce402

I have run my cpuset test and it completed successfully without any issue.

Tested-by: Waiman Long <longman@redhat.com>

Re: [PATCH v2 0/8] Fix SCHED_DEADLINE bandwidth accounting during suspend

[Juri Lelli]

On 07/03/25 14:00, Waiman Long wrote:
> On 3/6/25 9:10 AM, Juri Lelli wrote:
> > Hello!
> > 
> > Jon reported [1] a suspend regression on a Tegra board configured to
> > boot with isolcpus and bisected it to commit 53916d5fd3c0
> > ("sched/deadline: Check bandwidth overflow earlier for hotplug").
> > 
> > Root cause analysis pointed out that we are currently failing to
> > correctly clear and restore bandwidth accounting on root domains after
> > changes that initiate from partition_sched_domains(), as it is the case
> > for suspend operations on that board.
> > 
> > This is v2 [2] of the proposed approach to fix the issue. With respect
> > to v1, the following implements the approach by:
> > 
> > - 01: filter out DEADLINE special tasks
> > - 02: preparatory wrappers to be able to grab sched_domains_mutex on
> >        UP (remove !SMP wrappers - Waiman)
> > - 03: generalize unique visiting of root domains so that we can
> >        re-use the mechanism elsewhere
> > - 04: the bulk of the approach, clean and rebuild after changes
> > - 05: clean up a now redundant call
> > - 06: remove partition_and_rebuild_sched_domains() (Waiman)
> > - 07: stop exposing partition_sched_domains_locked (Waiman)
> > 
> > Please test and review. The set is also available at

...

> I have run my cpuset test and it completed successfully without any issue.
> 
> Tested-by: Waiman Long <longman@redhat.com>
> 

Thanks!
Juri