linux-kernel - [PATCH -next 11/21] cpuset: user local_partition

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Message-Id: <20251117024627.1128037-12-chenridong@huaweicloud.com>
Date: Mon, 17 Nov 2025 02:46:17 +0000
From: Chen Ridong <chenridong@...weicloud.com>
To: longman@...hat.com,
	tj@...nel.org,
	hannes@...xchg.org,
	mkoutny@...e.com
Cc: cgroups@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	lujialin4@...wei.com,
	chenridong@...wei.com
Subject: [PATCH -next 11/21] cpuset: user local_partition_disable() to invalidate local partition

From: Chen Ridong <chenridong@...wei.com>

Build on the local_partition_disable() infrastructure introduced in the
previous patch to handle local partition invalidation.

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_xcpus 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_xcpus based check ensures proper partition
state transitions under these conditions.

Signed-off-by: Chen Ridong <chenridong@...wei.com>
---
 kernel/cgroup/cpuset.c | 32 +++++++++-----------------------
 1 file changed, 9 insertions(+), 23 deletions(-)

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index fe166d7ed49d..770a28491cb7 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -2028,22 +2028,6 @@ 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;
-
-		goto write_error;
-	}
-
 	/*
 	 * The parent must be a partition root.
 	 * The new cpumask, if present, or the current cpus_allowed must
@@ -2619,7 +2603,7 @@ 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_disable(cp, PERR_NOTEXCL, tmp);
 				rcu_read_lock();
 			}
 		}
@@ -2659,8 +2643,7 @@ 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_disable(cs, trialcs->prs_err, tmp);
 		else
 			update_parent_effective_cpumask(cs, partcmd_update,
 							trialcs->effective_xcpus, tmp);
@@ -4104,18 +4087,21 @@ 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_disable(cs, cs->prs_err, 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