Commit 86888c7b authored by Waiman Long's avatar Waiman Long Committed by Tejun Heo
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cgroup/cpuset: Add warnings to catch inconsistency in exclusive CPUs 



Add WARN_ON_ONCE() statements whenever new exclusive CPUs are being
added to a partition root to catch inconsistency in the way exclusive
CPUs are being handled in the cpuset code.

Signed-off-by: default avatarWaiman Long <longman@redhat.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 6e6f9170

kernel/cgroup/cpuset.c

+33 −10
Original line number Diff line number Diff line
@@ -1453,13 +1453,15 @@ static int remote_partition_enable(struct cpuset *cs, int new_prs, 
	 * The requested exclusive_cpus must not be allocated to other

	 * partitions and it can't use up all the root's effective_cpus.

	 *

	 * Note that if there is any local partition root above it or

	 * remote partition root underneath it, its exclusive_cpus must

	 * have overlapped with subpartitions_cpus.

	 * The effective_xcpus mask can contain offline CPUs, but there must

	 * be at least one or more online CPUs present before it can be enabled.

	 *

	 * Note that creating a remote partition with any local partition root

	 * above it or remote partition root underneath it is not allowed.

	 */

	compute_effective_exclusive_cpumask(cs, tmp->new_cpus, NULL);

	if (cpumask_empty(tmp->new_cpus) ||

	    cpumask_intersects(tmp->new_cpus, subpartitions_cpus) ||

	WARN_ON_ONCE(cpumask_intersects(tmp->new_cpus, subpartitions_cpus));

	if (!cpumask_intersects(tmp->new_cpus, cpu_active_mask) ||

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

		return PERR_INVCPUS;
@@ -1555,6 +1557,7 @@ static void remote_cpus_update(struct cpuset *cs, struct cpumask *xcpus, 
	 * left in the top cpuset.

	 */

	if (adding) {

		WARN_ON_ONCE(cpumask_intersects(tmp->addmask, subpartitions_cpus));

		if (!capable(CAP_SYS_ADMIN))

			cs->prs_err = PERR_ACCESS;

		else if (cpumask_intersects(tmp->addmask, subpartitions_cpus) ||
@@ -1664,7 +1667,7 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd, 
	bool nocpu;



	lockdep_assert_held(&cpuset_mutex);

	WARN_ON_ONCE(is_remote_partition(cs));

	WARN_ON_ONCE(is_remote_partition(cs));	/* For local partition only */



	/*

	 * new_prs will only be changed for the partcmd_update and
@@ -1710,7 +1713,7 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd, 
		 * exclusive_cpus not set. Sibling conflict should only happen

		 * if exclusive_cpus isn't set.

		 */

		xcpus = tmp->new_cpus;

		xcpus = tmp->delmask;

		if (compute_effective_exclusive_cpumask(cs, xcpus, NULL))

			WARN_ON_ONCE(!cpumask_empty(cs->exclusive_cpus));
@@ -1731,8 +1734,19 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd, 
		if (nocpu)

			return PERR_NOCPUS;



		deleting = cpumask_and(tmp->delmask, xcpus, parent->effective_xcpus);

		if (deleting)

		/*

		 * This function will only be called when all the preliminary

		 * checks have passed. At this point, the following condition

		 * should hold.

		 *

		 * (cs->effective_xcpus & cpu_active_mask) ⊆ parent->effective_cpus

		 *

		 * Warn if it is not the case.

		 */

		cpumask_and(tmp->new_cpus, xcpus, cpu_active_mask);

		WARN_ON_ONCE(!cpumask_subset(tmp->new_cpus, parent->effective_cpus));



		deleting = true;

		subparts_delta++;

		new_prs = (cmd == partcmd_enable) ? PRS_ROOT : PRS_ISOLATED;

	} else if (cmd == partcmd_disable) {
@@ -1787,6 +1801,15 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd, 
			deleting = cpumask_and(tmp->delmask, tmp->delmask,

					       parent->effective_xcpus);

		}

		/*

		 * The new CPUs to be removed from parent's effective CPUs

		 * must be present.

		 */

		if (deleting) {

			cpumask_and(tmp->new_cpus, tmp->delmask, cpu_active_mask);

			WARN_ON_ONCE(!cpumask_subset(tmp->new_cpus, parent->effective_cpus));

		}



		/*

		 * Make partition invalid if parent's effective_cpus could

		 * become empty and there are tasks in the parent.