cpuset: fix failure to enable isolated partition when containing isolcpus

[ Upstream commit 216217ebee ]

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: 4a74e41888 ("cgroup/cpuset: Check partition conflict with housekeeping setup")
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Chen Ridong 2025-09-19 01:12:26 +00:00 • committed by Greg Kroah-Hartman
commit 44cd990ff3