cgroup/cpuset: Fix incorrect isolated_cpus update in update_parent_effective_cpumask()

jira NONE_AUTOMATION
Rebuild_History Non-Buildable kernel-5.14.0-570.17.1.el9_6
commit-author Waiman Long <[email protected]>
commit 668e041

Before commit f0af1bf ("cgroup/cpuset: Relax constraints to
partition & cpus changes"), a cpuset partition cannot be enabled if not
all the requested CPUs can be granted from the parent cpuset. After
that commit, a cpuset partition can be created even if the requested
exclusive CPUs contain CPUs not allowed its parent.  The delmask
containing exclusive CPUs to be removed from its parent wasn't
adjusted accordingly.

That is not a problem until the introduction of a new isolated_cpus
mask in commit 11e5f40 ("cgroup/cpuset: Keep track of CPUs in
isolated partitions") as the CPUs in the delmask may be added directly
into isolated_cpus.

As a result, isolated_cpus may incorrectly contain CPUs that are not
isolated leading to incorrect data reporting. Fix this by adjusting
the delmask to reflect the actual exclusive CPUs for the creation of
the partition.

Fixes: 11e5f40 ("cgroup/cpuset: Keep track of CPUs in isolated partitions")
	Signed-off-by: Waiman Long <[email protected]>
	Signed-off-by: Tejun Heo <[email protected]>
(cherry picked from commit 668e041)
	Signed-off-by: Jonathan Maple <[email protected]>

Author: PlaidCat

kernel/cgroup/cpuset.c

@@ -1952,9 +1952,9 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd,
 		if (nocpu)
 			return PERR_NOCPUS;
 
-		cpumask_copy(tmp->delmask, xcpus);
-		deleting = true;
-		subparts_delta++;
+		deleting = cpumask_and(tmp->delmask, xcpus, parent->effective_xcpus);
+		if (deleting)
+			subparts_delta++;
 		new_prs = (cmd == partcmd_enable) ? PRS_ROOT : PRS_ISOLATED;
 	} else if (cmd == partcmd_disable) {
 		/*