6.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: Waiman Long <longman@xxxxxxxxxx>
[ Upstream commit ff0ce721ec213499ec5a532041fb3a1db2dc5ecb ]
It was found that some hotplug operations may cause multiple
rebuild_sched_domains_locked() calls. Some of those intermediate calls
may use cpuset states not in the final correct form leading to incorrect
sched domain setting.
Fix this problem by using the existing force_rebuild flag to inhibit
immediate rebuild_sched_domains_locked() calls if set and only doing
one final call at the end. Also renaming the force_rebuild flag to
force_sd_rebuild to make its meaning for clear.
Signed-off-by: Waiman Long <longman@xxxxxxxxxx>
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
kernel/cgroup/cpuset.c | 33 +++++++++++++++++----------------
1 file changed, 17 insertions(+), 16 deletions(-)
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index e8f24483e05f..c03a2bc106d4 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -223,6 +223,13 @@ static cpumask_var_t isolated_cpus;
/* List of remote partition root children */
static struct list_head remote_children;
+/*
+ * A flag to force sched domain rebuild at the end of an operation while
+ * inhibiting it in the intermediate stages when set. Currently it is only
+ * set in hotplug code.
+ */
+static bool force_sd_rebuild;
+
/*
* Partition root states:
*
@@ -1442,7 +1449,7 @@ static void update_partition_sd_lb(struct cpuset *cs, int old_prs)
clear_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
}
- if (rebuild_domains)
+ if (rebuild_domains && !force_sd_rebuild)
rebuild_sched_domains_locked();
}
@@ -1805,7 +1812,7 @@ static void remote_partition_check(struct cpuset *cs, struct cpumask *newmask,
remote_partition_disable(child, tmp);
disable_cnt++;
}
- if (disable_cnt)
+ if (disable_cnt && !force_sd_rebuild)
rebuild_sched_domains_locked();
}
@@ -2415,7 +2422,8 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp,
}
rcu_read_unlock();
- if (need_rebuild_sched_domains && !(flags & HIER_NO_SD_REBUILD))
+ if (need_rebuild_sched_domains && !(flags & HIER_NO_SD_REBUILD) &&
+ !force_sd_rebuild)
rebuild_sched_domains_locked();
}
@@ -3077,7 +3085,8 @@ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
cs->flags = trialcs->flags;
spin_unlock_irq(&callback_lock);
- if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed)
+ if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed &&
+ !force_sd_rebuild)
rebuild_sched_domains_locked();
if (spread_flag_changed)
@@ -4478,11 +4487,9 @@ hotplug_update_tasks(struct cpuset *cs,
update_tasks_nodemask(cs);
}
-static bool force_rebuild;
-
void cpuset_force_rebuild(void)
{
- force_rebuild = true;
+ force_sd_rebuild = true;
}
/**
@@ -4630,15 +4637,9 @@ static void cpuset_handle_hotplug(void)
!cpumask_empty(subpartitions_cpus);
mems_updated = !nodes_equal(top_cpuset.effective_mems, new_mems);
- /*
- * In the rare case that hotplug removes all the cpus in
- * subpartitions_cpus, we assumed that cpus are updated.
- */
- if (!cpus_updated && !cpumask_empty(subpartitions_cpus))
- cpus_updated = true;
-
/* For v1, synchronize cpus_allowed to cpu_active_mask */
if (cpus_updated) {
+ cpuset_force_rebuild();
spin_lock_irq(&callback_lock);
if (!on_dfl)
cpumask_copy(top_cpuset.cpus_allowed, &new_cpus);
@@ -4694,8 +4695,8 @@ static void cpuset_handle_hotplug(void)
}
/* rebuild sched domains if cpus_allowed has changed */
- if (cpus_updated || force_rebuild) {
- force_rebuild = false;
+ if (force_sd_rebuild) {
+ force_sd_rebuild = false;
rebuild_sched_domains_cpuslocked();
}
--
2.43.0
