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cgroup/cpuset: Add warnings to catch inconsistency in exclusive CPUs

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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: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Waiman Long 2025-04-07 17:21:05 -04:00 committed by Tejun Heo
parent 6e6f9170dc
commit 86888c7bd1
1 changed files with 33 additions and 10 deletions
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43
kernel/cgroup/cpuset.c
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@ -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));
@ -1731,9 +1734,20 @@ 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)
subparts_delta++;
/*
* 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.