linux-kernel - [PATCH -next RFC 01/16] cpuset: use update_partition_sd_lb in update_cpumasks

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Message-Id: <20250928071306.3797436-2-chenridong@huaweicloud.com>
Date: Sun, 28 Sep 2025 07:12:51 +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 01/16] cpuset: use update_partition_sd_lb in update_cpumasks_hier

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

For cgroup v2, when a cpuset is not a valid partition root, it inherits
the CS_SCHED_LOAD_BALANCE flag from its parent. The existing logic in
update_cpumasks_hier() manually handled this inheritance condition.

This patch replaces the inline implementation with a call to the dedicated
update_partition_sd_lb() helper function, which already encapsulates the
same logic. The helper function comprehensively handles both the load
balance flag update and the necessary scheduling domain rebuild decision.

Signed-off-by: Chen Ridong <chenridong@...wei.com>
---
 kernel/cgroup/cpuset.c | 16 +++-------------
 1 file changed, 3 insertions(+), 13 deletions(-)

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 52468d2c178a..052f9e0c7a65 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -1257,6 +1257,8 @@ static void update_partition_sd_lb(struct cpuset *cs, int old_prs)
 	bool rebuild_domains = (new_prs > 0) || (old_prs > 0);
 	bool new_lb;
 
+	if (!cpuset_v2())
+		return;
 	/*
 	 * If cs is not a valid partition root, the load balance state
 	 * will follow its parent.
@@ -2276,19 +2278,7 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp,
 			!cpumask_equal(cp->cpus_allowed, cp->effective_cpus));
 
 		cpuset_update_tasks_cpumask(cp, cp->effective_cpus);
-
-		/*
-		 * On default hierarchy, inherit the CS_SCHED_LOAD_BALANCE
-		 * from parent if current cpuset isn't a valid partition root
-		 * and their load balance states differ.
-		 */
-		if (cpuset_v2() && !is_partition_valid(cp) &&
-		    (is_sched_load_balance(parent) != is_sched_load_balance(cp))) {
-			if (is_sched_load_balance(parent))
-				set_bit(CS_SCHED_LOAD_BALANCE, &cp->flags);
-			else
-				clear_bit(CS_SCHED_LOAD_BALANCE, &cp->flags);
-		}
+		update_partition_sd_lb(cp, old_prs);
 
 		/*
 		 * On legacy hierarchy, if the effective cpumask of any non-
-- 
2.34.1