linux-kernel - [PATCH cgroup/for-next v2 2/2] cpuset: Use new excpus for nocpu error check when enabling root partition

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Message-Id: <20250919011227.2991696-3-chenridong@huaweicloud.com>
Date: Fri, 19 Sep 2025 01:12:27 +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 cgroup/for-next v2 2/2] cpuset: Use new excpus for nocpu error check when enabling root partition

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

A previous patch fixed a bug where new_prs should be assigned before
checking housekeeping conflicts. This patch addresses another potential
issue: the nocpu error check currently uses the xcpus which is not updated.
Although no issue has been observed so far, the check should be performed
using the new effective exclusive cpus.

The comment has been removed because the function returns an error if
nocpu checking fails, which is unrelated to the parent.

Signed-off-by: Chen Ridong <chenridong@...wei.com>
Reviewed-by: Waiman Long <longman@...hat.com>
---
 kernel/cgroup/cpuset.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 2b7e2f17577e..44d65890326a 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -1818,11 +1818,7 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd,
 		if (prstate_housekeeping_conflict(new_prs, xcpus))
 			return PERR_HKEEPING;
 
-		/*
-		 * A parent can be left with no CPU as long as there is no
-		 * task directly associated with the parent partition.
-		 */
-		if (nocpu)
+		if (tasks_nocpu_error(parent, cs, xcpus))
 			return PERR_NOCPUS;
 
 		/*
-- 
2.34.1