Commit c2cf0767 authored by Zqiang's avatar Zqiang Committed by Paul E. McKenney
Browse files

rcu: Avoid running boost kthreads on isolated CPUs 



When the boost kthreads are created on systems with nohz_full CPUs,
the cpus_allowed_ptr is set to housekeeping_cpumask(HK_FLAG_KTHREAD).
However, when the rcu_boost_kthread_setaffinity() is called, the original
affinity will be changed and these kthreads can subsequently run on
nohz_full CPUs.  This commit makes rcu_boost_kthread_setaffinity()
restrict these boost kthreads to housekeeping CPUs.

Signed-off-by: default avatarZqiang <qiang.zhang1211@gmail.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 17ea3718

kernel/rcu/tree_plugin.h

+2 −1
Original line number Diff line number Diff line
@@ -1203,8 +1203,9 @@ static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu) 
		if ((mask & leaf_node_cpu_bit(rnp, cpu)) &&

		    cpu != outgoingcpu)

			cpumask_set_cpu(cpu, cm);

	cpumask_and(cm, cm, housekeeping_cpumask(HK_FLAG_RCU));

	if (cpumask_weight(cm) == 0)

		cpumask_setall(cm);

		cpumask_copy(cm, housekeeping_cpumask(HK_FLAG_RCU));

	set_cpus_allowed_ptr(t, cm);

	free_cpumask_var(cm);

}