From: Chen Wandun <chenwandun@lixiang.com>
Date: Mon, 11 May 2026 08:18:38 +0000 (+0800)
Subject: cgroup/cpuset: Skip hardwall ancestor scan in cpuset v2 in cpuset_current_node_allowed()
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=be2689c9ed47bde6f15a24c9845f6fc1ec52502f;p=thirdparty%2Flinux.git

cgroup/cpuset: Skip hardwall ancestor scan in cpuset v2 in cpuset_current_node_allowed()

Cgroup v2 doesn't have the concept of memory hardwall, only top_cpuset
has CS_MEM_EXCLUSIVE/CS_MEM_HARDWALL flags, nearest_hardwall_ancestor
always returns top_cpuset with all nodes set, so no need to acquire
callback_lock and scan up cpuset.

Suggested-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Chen Wandun <chenwandun@lixiang.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
---

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 3fbf6e7f68c31..74d5c494d6aec 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -4231,6 +4231,9 @@ bool cpuset_current_node_allowed(int node, gfp_t gfp_mask)
 	if (gfp_mask & __GFP_HARDWALL)	/* If hardwall request, stop here */
 		return false;
 
+	if (cpuset_v2())
+		return true;
+
 	/* Not hardwall and node outside mems_allowed: scan up cpusets */
 	spin_lock_irqsave(&callback_lock, flags);