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Message-Id: <20250928071306.3797436-9-chenridong@huaweicloud.com>
Date: Sun, 28 Sep 2025 07:12:58 +0000
From: Chen Ridong <chenridong@...weicloud.com>
To: longman@...hat.com,
tj@...nel.org,
hannes@...xchg.org,
mkoutny@...e.com
Cc: cgups@...r.kernel.org,
linux-kernel@...r.kernel.org,
lujialin4@...wei.com,
chenridong@...wei.com
Subject: [PATCH -next RFC 08/16] cpuset: introduce local_partition_invalidate()
From: Chen Ridong <chenridong@...wei.com>
Build on the partition_disable() infrastructure introduced in the previous
patch to handle local partition invalidation.
The local_partition_invalidate() function factors out the local partition
invalidation logic from update_parent_effective_cpumask(), which delegates
to partition_disable() to complete the invalidation process.
Additionally, correct the transition logic in cpuset_hotplug_update_tasks()
when determining whether to transition an invalid partition root, the check
should be based on non-empty user_cpus rather than non-empty
effective_xcpus. This correction addresses the scenario where
exclusive_cpus is not set but cpus_allowed is configured - in this case,
effective_xcpus may be empty even though the partition should be considered
for re-enablement. The user_cpus-based check ensures proper partition state
transitions under these conditions.
Signed-off-by: Chen Ridong <chenridong@...wei.com>
---
kernel/cgroup/cpuset.c | 66 +++++++++++++++++++++++++++---------------
1 file changed, 42 insertions(+), 24 deletions(-)
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 87ba43e93540..e460d03286ba 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -1911,6 +1911,39 @@ static void local_partition_disable(struct cpuset *cs, struct tmpmasks *tmp)
}
}
+/**
+ * local_partition_invalidate - Invalidate a local partition
+ * @cs: Target cpuset (local partition root) to invalidate
+ * @tmp: Temporary masks
+ */
+static void local_partition_invalidate(struct cpuset *cs, struct tmpmasks *tmp)
+{
+ struct cpumask *xcpus = user_xcpus(cs);
+ struct cpuset *parent = parent_cs(cs);
+ int new_prs = cs->partition_root_state;
+ bool cpumask_updated = false;
+
+ lockdep_assert_held(&cpuset_mutex);
+ WARN_ON_ONCE(is_remote_partition(cs)); /* For local partition only */
+
+ if (is_partition_invalid(cs))
+ return;
+ /*
+ * Make the current partition invalid.
+ */
+ if (is_partition_valid(parent))
+ cpumask_updated = cpumask_and(tmp->addmask,
+ xcpus, parent->effective_xcpus);
+ if (cs->partition_root_state > 0)
+ new_prs = -cs->partition_root_state;
+
+ partition_disable(cs, parent, new_prs, cs->prs_err);
+ if (cpumask_updated) {
+ cpuset_update_tasks_cpumask(parent, tmp->addmask);
+ update_sibling_cpumasks(parent, cs, tmp);
+ }
+}
+
/**
* update_parent_effective_cpumask - update effective_cpus mask of parent cpuset
* @cs: The cpuset that requests change in partition root state
@@ -1972,23 +2005,6 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd,
adding = deleting = false;
old_prs = new_prs = cs->partition_root_state;
- if (cmd == partcmd_invalidate) {
- if (is_partition_invalid(cs))
- return 0;
-
- /*
- * Make the current partition invalid.
- */
- if (is_partition_valid(parent))
- adding = cpumask_and(tmp->addmask,
- xcpus, parent->effective_xcpus);
- if (old_prs > 0) {
- new_prs = -old_prs;
- subparts_delta--;
- }
- goto write_error;
- }
-
/*
* The parent must be a partition root.
* The new cpumask, if present, or the current cpus_allowed must
@@ -2552,7 +2568,7 @@ static int cpus_allowed_validate_change(struct cpuset *cs, struct cpuset *trialc
if (is_partition_valid(cp) &&
cpumask_intersects(xcpus, cp->effective_xcpus)) {
rcu_read_unlock();
- update_parent_effective_cpumask(cp, partcmd_invalidate, NULL, tmp);
+ local_partition_invalidate(cp, tmp);
rcu_read_lock();
}
}
@@ -2592,8 +2608,7 @@ static void partition_cpus_change(struct cpuset *cs, struct cpuset *trialcs,
trialcs->effective_xcpus, tmp);
} else {
if (trialcs->prs_err)
- update_parent_effective_cpumask(cs, partcmd_invalidate,
- NULL, tmp);
+ local_partition_invalidate(cs, tmp);
else
update_parent_effective_cpumask(cs, partcmd_update,
trialcs->effective_xcpus, tmp);
@@ -4037,18 +4052,21 @@ static void cpuset_hotplug_update_tasks(struct cpuset *cs, struct tmpmasks *tmp)
* partitions.
*/
if (is_local_partition(cs) && (!is_partition_valid(parent) ||
- tasks_nocpu_error(parent, cs, &new_cpus)))
+ tasks_nocpu_error(parent, cs, &new_cpus))) {
partcmd = partcmd_invalidate;
+ local_partition_invalidate(cs, tmp);
+ }
/*
* On the other hand, an invalid partition root may be transitioned
- * back to a regular one with a non-empty effective xcpus.
+ * back to a regular one with a non-empty user xcpus.
*/
else if (is_partition_valid(parent) && is_partition_invalid(cs) &&
- !cpumask_empty(cs->effective_xcpus))
+ !cpumask_empty(user_xcpus(cs))) {
partcmd = partcmd_update;
+ update_parent_effective_cpumask(cs, partcmd, NULL, tmp);
+ }
if (partcmd >= 0) {
- update_parent_effective_cpumask(cs, partcmd, NULL, tmp);
if ((partcmd == partcmd_invalidate) || is_partition_valid(cs)) {
compute_partition_effective_cpumask(cs, &new_cpus);
cpuset_force_rebuild();
--
2.34.1
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