[PATCH 4.18 125/168] sched/topology: Set correct NUMA topology type

[Greg Kroah-Hartman]

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Srikar Dronamraju <srikar at linux.vnet.ibm.com>

[ Upstream commit e5e96fafd9028b1478b165db78c52d981c14f471 ]

With the following commit:

  051f3ca02e46 ("sched/topology: Introduce NUMA identity node sched domain")

the scheduler introduced a new NUMA level. However this leads to the NUMA topology
on 2 node systems to not be marked as NUMA_DIRECT anymore.

After this commit, it gets reported as NUMA_BACKPLANE, because
sched_domains_numa_level is now 2 on 2 node systems.

Fix this by allowing setting systems that have up to 2 NUMA levels as
NUMA_DIRECT.

While here remove code that assumes that level can be 0.

Signed-off-by: Srikar Dronamraju <srikar at linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz at infradead.org>
Cc: Andre Wild <wild at linux.vnet.ibm.com>
Cc: Heiko Carstens <heiko.carstens at de.ibm.com>
Cc: Linus Torvalds <torvalds at linux-foundation.org>
Cc: Mel Gorman <mgorman at techsingularity.net>
Cc: Michael Ellerman <mpe at ellerman.id.au>
Cc: Peter Zijlstra <peterz at infradead.org>
Cc: Rik van Riel <riel at surriel.com>
Cc: Suravee Suthikulpanit <suravee.suthikulpanit at amd.com>
Cc: Thomas Gleixner <tglx at linutronix.de>
Cc: linuxppc-dev <linuxppc-dev at lists.ozlabs.org>
Fixes: 051f3ca02e46 "Introduce NUMA identity node sched domain"
Link: http://lkml.kernel.org/r/1533920419-17410-1-git-send-email-srikar@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo at kernel.org>
Signed-off-by: Sasha Levin <alexander.levin at microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 kernel/sched/topology.c |    5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -1295,7 +1295,7 @@ static void init_numa_topology_type(void
 
 	n = sched_max_numa_distance;
 
-	if (sched_domains_numa_levels <= 1) {
+	if (sched_domains_numa_levels <= 2) {
 		sched_numa_topology_type = NUMA_DIRECT;
 		return;
 	}
@@ -1380,9 +1380,6 @@ void sched_init_numa(void)
 			break;
 	}
 
-	if (!level)
-		return;
-
 	/*
 	 * 'level' contains the number of unique distances
 	 *