Merge branch 'linus' into perf/urgent, to synchronize with upstream

Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 39 insertions, 0 deletions

diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 6ec1e595b1d4..dfb64c08a407 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -1880,6 +1880,42 @@ static struct sched_domain *build_sched_domain(struct sched_domain_topology_leve
 }
 
 /*
+ * Ensure topology masks are sane, i.e. there are no conflicts (overlaps) for
+ * any two given CPUs at this (non-NUMA) topology level.
+ */
+static bool topology_span_sane(struct sched_domain_topology_level *tl,
+			      const struct cpumask *cpu_map, int cpu)
+{
+	int i;
+
+	/* NUMA levels are allowed to overlap */
+	if (tl->flags & SDTL_OVERLAP)
+		return true;
+
+	/*
+	 * Non-NUMA levels cannot partially overlap - they must be either
+	 * completely equal or completely disjoint. Otherwise we can end up
+	 * breaking the sched_group lists - i.e. a later get_group() pass
+	 * breaks the linking done for an earlier span.
+	 */
+	for_each_cpu(i, cpu_map) {
+		if (i == cpu)
+			continue;
+		/*
+		 * We should 'and' all those masks with 'cpu_map' to exactly
+		 * match the topology we're about to build, but that can only
+		 * remove CPUs, which only lessens our ability to detect
+		 * overlaps
+		 */
+		if (!cpumask_equal(tl->mask(cpu), tl->mask(i)) &&
+		    cpumask_intersects(tl->mask(cpu), tl->mask(i)))
+			return false;
+	}
+
+	return true;
+}
+
+/*
  * Find the sched_domain_topology_level where all CPU capacities are visible
  * for all CPUs.
  */
@@ -1975,6 +2011,9 @@ build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *att
 				has_asym = true;
 			}
 
+			if (WARN_ON(!topology_span_sane(tl, cpu_map, i)))
+				goto error;
+
 			sd = build_sched_domain(tl, cpu_map, attr, sd, dflags, i);
 
 			if (tl == sched_domain_topology)