On 8/20/26 8:41 AM, Guopeng Zhang wrote:
From: Guopeng Zhang <[email protected]>
When a housekeeping check rejects a root-to-isolated or isolated-to-root
change, update_prstate() marks the partition invalid but leaves its
effective_xcpus allocated. Those CPUs remain missing from the partition
which owns the invalidated subtree.
Disable a rejected remote partition with remote_partition_disable().
For a local partition, return effective_xcpus to its parent before
recording the invalid state. Use the complete mask because descendants
are invalidated along with the parent and their CPUs return at the same
time.
Fixes: 103b08709e8a ("cgroup/cpuset: Fail if isolated and nohz_full don't leave any
housekeeping")
Signed-off-by: Guopeng Zhang <[email protected]>
---
kernel/cgroup/cpuset.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 853942c1afeb..a616012927be 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -3020,10 +3020,21 @@ static int update_prstate(struct cpuset *cs, int
new_prs)
compute_partition_owned_cpumask(cs, tmpmask.new_cpus);
if (((new_prs == PRS_ISOLATED) &&
!isolated_cpus_can_update(tmpmask.new_cpus, NULL)) ||
- prstate_housekeeping_conflict(new_prs, tmpmask.new_cpus))
+ prstate_housekeeping_conflict(new_prs, tmpmask.new_cpus)) {
err = PERR_HKEEPING;
- else
+ if (is_remote_partition(cs)) {
+ WRITE_ONCE(cs->prs_err, err);
This WRITE_ONCE() is not necessary as it will be done later in the
function.
+ remote_partition_disable(cs, &tmpmask);
+ } else {
+ spin_lock_irq(&callback_lock);
+ partition_xcpus_del(old_prs, parent,
cs->effective_xcpus);
+ spin_unlock_irq(&callback_lock);
+ cpuset_update_tasks_cpumask(parent,
tmpmask.new_cpus);
+ update_sibling_cpumasks(parent, cs, &tmpmask);
+ }
This code to disable the partition is duplicating what is being done in
the last else clause of the outer if, but in a somewhat different way.
That is not good programming practice. You can either jump to the
partition disabling code below or separate out the partition disabling
code controlled by a separate control flag and set the flag to do it.
Cheers,
Longman
+ } else {
isolcpus_updated = true;
+ }
} else {
/*
* Switching back to member is always allowed even if it
