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.

Zqiang committed 5 years ago

Commit c2cf0761 parent 17ea3711 file · +2 −1Browse files

Showing the changes to kernel (1 of 1 file). Show all

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kernel/rcu/tree_plugin.h+2−1

@@ -1203,8 +1203,9 @@ static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu) · 1202 unmodified lines
1203	1203	if ((mask & leaf_node_cpu_bit(rnp, cpu)) &&
1204	1204	cpu != outgoingcpu)
1205	1205	cpumask_set_cpu(cpu, cm);
	1206	+ cpumask_and(cm, cm, housekeeping_cpumask(HK_FLAG_RCU));
1206	1207	if (cpumask_weight(cm) == 0)
1207		− cpumask_setall(cm);
	1208	+ cpumask_copy(cm, housekeeping_cpumask(HK_FLAG_RCU));
1208	1209	set_cpus_allowed_ptr(t, cm);
1209	1210	free_cpumask_var(cm);
1210	1211	}