Commit 292fd843 authored by Waiman Long's avatar Waiman Long Committed by Tejun Heo
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cgroup/cpuset: Fix partition root's cpuset.cpus update bug 



It was found that commit 7a2127e6 ("cpuset: Call
set_cpus_allowed_ptr() with appropriate mask for task") introduced a bug
that corrupted "cpuset.cpus" of a partition root when it was updated.

It is because the tmp->new_cpus field of the passed tmp parameter
of update_parent_subparts_cpumask() should not be used at all as
it contains important cpumask data that should not be overwritten.
Fix it by using tmp->addmask instead.

Also update update_cpumask() to make sure that trialcs->cpu_allowed
will not be corrupted until it is no longer needed.

Fixes: 7a2127e6 ("cpuset: Call set_cpus_allowed_ptr() with appropriate mask for task")
Signed-off-by: default avatarWaiman Long <longman@redhat.com>
Cc: stable@vger.kernel.org # v6.2+
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent fcdb1eda

kernel/cgroup/cpuset.c

+10 −2
Original line number Diff line number Diff line
@@ -1513,7 +1513,7 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, 
	spin_unlock_irq(&callback_lock);



	if (adding || deleting)

		update_tasks_cpumask(parent, tmp->new_cpus);

		update_tasks_cpumask(parent, tmp->addmask);



	/*

	 * Set or clear CS_SCHED_LOAD_BALANCE when partcmd_update, if necessary.
@@ -1770,10 +1770,13 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs, 
	/*

	 * Use the cpumasks in trialcs for tmpmasks when they are pointers

	 * to allocated cpumasks.

	 *

	 * Note that update_parent_subparts_cpumask() uses only addmask &

	 * delmask, but not new_cpus.

	 */

	tmp.addmask  = trialcs->subparts_cpus;

	tmp.delmask  = trialcs->effective_cpus;

	tmp.new_cpus = trialcs->cpus_allowed;

	tmp.new_cpus = NULL;

#endif



	retval = validate_change(cs, trialcs);
@@ -1838,6 +1841,11 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs, 
	}

	spin_unlock_irq(&callback_lock);



#ifdef CONFIG_CPUMASK_OFFSTACK

	/* Now trialcs->cpus_allowed is available */

	tmp.new_cpus = trialcs->cpus_allowed;

#endif



	/* effective_cpus will be updated here */

	update_cpumasks_hier(cs, &tmp, false);