linux-kernel - [PATCH -next 2/3] cpuset: remove global remote

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Message-Id: <20251110015228.897736-3-chenridong@huaweicloud.com>
Date: Mon, 10 Nov 2025 01:52:27 +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 2/3] cpuset: remove global remote_children list

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

The remote_children list is used to track all remote partitions attached
to a cpuset. However, it serves no other purpose. Using a boolean flag to
indicate whether a cpuset is a remote partition is a more direct approach,
making remote_children unnecessary.

This patch replaces the list with a remote_partition flag in the cpuset
structure and removes remote_children entirely.

Signed-off-by: Chen Ridong <chenridong@...wei.com>
---
 kernel/cgroup/cpuset-internal.h |  4 ++--
 kernel/cgroup/cpuset.c          | 14 +++++---------
 2 files changed, 7 insertions(+), 11 deletions(-)

diff --git a/kernel/cgroup/cpuset-internal.h b/kernel/cgroup/cpuset-internal.h
index 5cac42c5fd97..7308e8bc4dde 100644
--- a/kernel/cgroup/cpuset-internal.h
+++ b/kernel/cgroup/cpuset-internal.h
@@ -172,8 +172,8 @@ struct cpuset {
 	/* Handle for cpuset.cpus.partition */
 	struct cgroup_file partition_file;
 
-	/* Remote partition silbling list anchored at remote_children */
-	struct list_head remote_sibling;
+	/* Whether cpuset is a remote partition */
+	bool remote_partition;
 
 	/* Used to merge intersecting subsets for generate_sched_domains */
 	struct uf_node node;
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index c90476d52f09..c357bfb69fe2 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -94,9 +94,6 @@ static bool isolated_cpus_updating;
 static cpumask_var_t	boot_hk_cpus;
 static bool		have_boot_isolcpus;
 
-/* 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.
  * It can be set in
@@ -219,7 +216,7 @@ static struct cpuset top_cpuset = {
 		 BIT(CS_MEM_EXCLUSIVE) | BIT(CS_SCHED_LOAD_BALANCE),
 	.partition_root_state = PRS_ROOT,
 	.relax_domain_level = -1,
-	.remote_sibling = LIST_HEAD_INIT(top_cpuset.remote_sibling),
+	.remote_partition = false,
 };
 
 /*
@@ -1572,7 +1569,7 @@ static int compute_trialcs_excpus(struct cpuset *trialcs, struct cpuset *cs)
 
 static inline bool is_remote_partition(struct cpuset *cs)
 {
-	return !list_empty(&cs->remote_sibling);
+	return cs->remote_partition;
 }
 
 static inline bool is_local_partition(struct cpuset *cs)
@@ -1621,7 +1618,7 @@ static int remote_partition_enable(struct cpuset *cs, int new_prs,
 
 	spin_lock_irq(&callback_lock);
 	partition_xcpus_add(new_prs, NULL, tmp->new_cpus);
-	list_add(&cs->remote_sibling, &remote_children);
+	cs->remote_partition = true;
 	cpumask_copy(cs->effective_xcpus, tmp->new_cpus);
 	spin_unlock_irq(&callback_lock);
 	update_isolation_cpumasks();
@@ -1651,7 +1648,7 @@ static void remote_partition_disable(struct cpuset *cs, struct tmpmasks *tmp)
 	WARN_ON_ONCE(!cpumask_subset(cs->effective_xcpus, subpartitions_cpus));
 
 	spin_lock_irq(&callback_lock);
-	list_del_init(&cs->remote_sibling);
+	cs->remote_partition = false;
 	partition_xcpus_del(cs->partition_root_state, NULL, cs->effective_xcpus);
 	if (cs->prs_err)
 		cs->partition_root_state = -cs->partition_root_state;
@@ -3603,7 +3600,7 @@ cpuset_css_alloc(struct cgroup_subsys_state *parent_css)
 	__set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
 	fmeter_init(&cs->fmeter);
 	cs->relax_domain_level = -1;
-	INIT_LIST_HEAD(&cs->remote_sibling);
+	cs->remote_partition = false;
 
 	/* Set CS_MEMORY_MIGRATE for default hierarchy */
 	if (cpuset_v2())
@@ -3874,7 +3871,6 @@ int __init cpuset_init(void)
 	nodes_setall(top_cpuset.effective_mems);
 
 	fmeter_init(&top_cpuset.fmeter);
-	INIT_LIST_HEAD(&remote_children);
 
 	BUG_ON(!alloc_cpumask_var(&cpus_attach, GFP_KERNEL));
 
-- 
2.34.1