From 44cd990ff390e11f559630ec6ef11cb3e1e19564 Mon Sep 17 00:00:00 2001 From: Chen Ridong Date: Fri, 19 Sep 2025 01:12:26 +0000 Subject: [PATCH] cpuset: fix failure to enable isolated partition when containing isolcpus [ Upstream commit 216217ebee16afc4d79c3e86a736d87175c18e68 ] The 'isolcpus' parameter specified at boot time can be assigned to an isolated partition. While it is valid put the 'isolcpus' in an isolated partition, attempting to change a member cpuset to an isolated partition will fail if the cpuset contains any 'isolcpus'. For example, the system boots with 'isolcpus=9', and the following configuration works correctly: # cd /sys/fs/cgroup/ # mkdir test # echo 1 > test/cpuset.cpus # echo isolated > test/cpuset.cpus.partition # cat test/cpuset.cpus.partition isolated # echo 9 > test/cpuset.cpus # cat test/cpuset.cpus.partition isolated # cat test/cpuset.cpus 9 However, the following steps to convert a member cpuset to an isolated partition will fail: # cd /sys/fs/cgroup/ # mkdir test # echo 9 > test/cpuset.cpus # echo isolated > test/cpuset.cpus.partition # cat test/cpuset.cpus.partition isolated invalid (partition config conflicts with housekeeping setup) The issue occurs because the new partition state (new_prs) is used for validation against housekeeping constraints before it has been properly updated. To resolve this, move the assignment of new_prs before the housekeeping validation check when enabling a root partition. Fixes: 4a74e418881f ("cgroup/cpuset: Check partition conflict with housekeeping setup") Signed-off-by: Chen Ridong Reviewed-by: Waiman Long Signed-off-by: Tejun Heo Signed-off-by: Sasha Levin --- kernel/cgroup/cpuset.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 27adb04df675..fef93032fe7e 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1716,6 +1716,7 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd, xcpus = tmp->delmask; if (compute_effective_exclusive_cpumask(cs, xcpus, NULL)) WARN_ON_ONCE(!cpumask_empty(cs->exclusive_cpus)); + new_prs = (cmd == partcmd_enable) ? PRS_ROOT : PRS_ISOLATED; /* * Enabling partition root is not allowed if its @@ -1748,7 +1749,6 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd, deleting = true; subparts_delta++; - new_prs = (cmd == partcmd_enable) ? PRS_ROOT : PRS_ISOLATED; } else if (cmd == partcmd_disable) { /* * May need to add cpus back to parent's effective_cpus