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

From: Greg Kroah-Hartman
Date: Mon Oct 08 2018 - 14:51:42 EST

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


From: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>

[ 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

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

Signed-off-by: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Andre Wild <wild@xxxxxxxxxxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Cc: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linuxppc-dev <linuxppc-dev@xxxxxxxxxxxxxxxx>
Fixes: 051f3ca02e46 "Introduce NUMA identity node sched domain"
Link: http://lkml.kernel.org/r/1533920419-17410-1-git-send-email-srikar@xxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
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;
@@ -1380,9 +1380,6 @@ void sched_init_numa(void)

- if (!level)
- return;
* 'level' contains the number of unique distances