Commit b1034a69 authored by Waiman Long's avatar Waiman Long Committed by Tejun Heo
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cgroup/cpuset: Ensure domain isolated CPUs stay in root or isolated partition 



Commit 4a74e418 ("cgroup/cpuset: Check partition conflict with
housekeeping setup") is supposed to ensure that domain isolated CPUs
designated by the "isolcpus" boot command line option stay either in
root partition or in isolated partitions. However, the required check
wasn't implemented when a remote partition was created or when an
existing partition changed type from "root" to "isolated".

Even though this is a relatively minor issue, we still need to add the
required prstate_housekeeping_conflict() call in the right places to
ensure that the rule is strictly followed.

The following steps can be used to reproduce the problem before this
fix.

  # fmt -1 /proc/cmdline | grep isolcpus
  isolcpus=9
  # cd /sys/fs/cgroup/
  # echo +cpuset > cgroup.subtree_control
  # mkdir test
  # echo 9 > test/cpuset.cpus
  # echo isolated > test/cpuset.cpus.partition
  # cat test/cpuset.cpus.partition
  isolated
  # cat test/cpuset.cpus.effective
  9
  # echo root > test/cpuset.cpus.partition
  # cat test/cpuset.cpus.effective
  9
  # cat test/cpuset.cpus.partition
  root

With this fix, the last few steps will become:

  # echo root > test/cpuset.cpus.partition
  # cat test/cpuset.cpus.effective
  0-8,10-95
  # cat test/cpuset.cpus.partition
  root invalid (partition config conflicts with housekeeping setup)

Reported-by: default avatarChen Ridong <chenridong@huawei.com>
Signed-off-by: default avatarWaiman Long <longman@redhat.com>
Reviewed-by: default avatarChen Ridong <chenridong@huawei.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 6cfeddbf

kernel/cgroup/cpuset.c

+6 −4
Original line number Diff line number Diff line
@@ -1610,8 +1610,9 @@ static int remote_partition_enable(struct cpuset *cs, int new_prs, 
	if (!cpumask_intersects(tmp->new_cpus, cpu_active_mask) ||

	    cpumask_subset(top_cpuset.effective_cpus, tmp->new_cpus))

		return PERR_INVCPUS;

	if ((new_prs == PRS_ISOLATED) &&

	    !isolated_cpus_can_update(tmp->new_cpus, NULL))

	if (((new_prs == PRS_ISOLATED) &&

	     !isolated_cpus_can_update(tmp->new_cpus, NULL)) ||

	    prstate_housekeeping_conflict(new_prs, tmp->new_cpus))

		return PERR_HKEEPING;



	spin_lock_irq(&callback_lock);
@@ -3062,8 +3063,9 @@ static int update_prstate(struct cpuset *cs, int new_prs) 
		 * A change in load balance state only, no change in cpumasks.

		 * Need to update isolated_cpus.

		 */

		if ((new_prs == PRS_ISOLATED) &&

		    !isolated_cpus_can_update(cs->effective_xcpus, NULL))

		if (((new_prs == PRS_ISOLATED) &&

		     !isolated_cpus_can_update(cs->effective_xcpus, NULL)) ||

		    prstate_housekeeping_conflict(new_prs, cs->effective_xcpus))

			err = PERR_HKEEPING;

		else

			isolcpus_updated = true;