From 216217ebee16afc4d79c3e86a736d87175c18e68 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 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 --- 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 44231cb1d83fe..2b7e2f17577ea 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1806,6 +1806,7 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd, xcpus = tmp->delmask; if (compute_excpus(cs, xcpus)) 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 @@ -1838,7 +1839,6 @@ 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 -- 2.47.3