On Tue, Apr 25, 2017 at 05:39:37PM +0200, Peter Zijlstra wrote:
> On Tue, Apr 25, 2017 at 05:27:03PM +0200, Peter Zijlstra wrote:
> > Ah! the asymmetric setup, where @sibling is entirely uninitialized for
> > the top domain.
Like so then...
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -509,6 +509,11 @@ static void build_group_mask(struct sche
for_each_cpu(i, sg_span) {
sibling = *per_cpu_ptr(sdd->sd, i);
+ /*
+ * Can happen in the asymmetric case, where these siblings are
+ * unused. The mask will not be empty because those CPUs that
+ * do have the top domain _should_ span the domain.
+ */
if (!sibling->child)
continue;
@@ -518,6 +523,9 @@ static void build_group_mask(struct sche
cpumask_set_cpu(i, sched_group_mask(sg));
}
+
+ /* We must not have empty masks here */
+ WARN_ON_ONCE(cpumask_empty(sched_group_mask(sg)));
}
/*
