| Message ID | 20220831180805.2693546-10-paulmck@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Miscellaneous fixes for v6.1 | expand |
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 207617f69aa56..32b424b571bd9 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -1243,8 +1243,11 @@ static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu) cpu != outgoingcpu) cpumask_set_cpu(cpu, cm); cpumask_and(cm, cm, housekeeping_cpumask(HK_TYPE_RCU)); - if (cpumask_empty(cm)) + if (cpumask_empty(cm)) { cpumask_copy(cm, housekeeping_cpumask(HK_TYPE_RCU)); + if (outgoingcpu >= 0) + cpumask_clear_cpu(outgoingcpu, cm); + } set_cpus_allowed_ptr(t, cm); mutex_unlock(&rnp->boost_kthread_mutex); free_cpumask_var(cm);
The rcu_boost_kthread_setaffinity() function removes the outgoing CPU from the set_cpus_allowed() mask for the corresponding leaf rcu_node structure's rcub priority-boosting kthread. Except that if the outgoing CPU will leave that structure without any online CPUs, the mask is set to the housekeeping CPU mask from housekeeping_cpumask(). Which is fine unless the outgoing CPU happens to be a housekeeping CPU. This commit therefore removes the outgoing CPU from the housekeeping mask. This would of course be problematic if the outgoing CPU was the last online housekeeping CPU, but in that case you are in a world of hurt anyway. If someone comes up with a valid use case for a system needing all the housekeeping CPUs to be offline, further adjustments can be made. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> --- kernel/rcu/tree_plugin.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)