This is a note to let you know that I've just added the patch titled
powerpc/papr_scm: Update the NUMA distance table for the target node
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
powerpc-papr_scm-update-the-numa-distance-table-for-.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 3c008671fed52c8e248a3e549f3b90f463661181
Author: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Date: Tue Apr 4 09:44:33 2023 +0530
powerpc/papr_scm: Update the NUMA distance table for the target node
[ Upstream commit b277fc793daf258877b4c0744b52f69d6e6ba22e ]
Platform device helper routines won't update the NUMA distance table
while creating a platform device, even if the device is present on a
NUMA node that doesn't have memory or CPU. This is especially true for
pmem devices. If the target node of the pmem device is not online, we
find the nearest online node to the device and associate the pmem device
with that online node. To find the nearest online node, we should have
the numa distance table updated correctly. Update the distance
information during the device probe.
For a papr scm device on NUMA node 3 distance_lookup_table value for
distance_ref_points_depth = 2 before and after fix is below:
Before fix:
node 3 distance depth 0 - 0
node 3 distance depth 1 - 0
node 4 distance depth 0 - 4
node 4 distance depth 1 - 2
node 5 distance depth 0 - 5
node 5 distance depth 1 - 1
After fix
node 3 distance depth 0 - 3
node 3 distance depth 1 - 1
node 4 distance depth 0 - 4
node 4 distance depth 1 - 2
node 5 distance depth 0 - 5
node 5 distance depth 1 - 1
Without the fix, the nearest numa node to the pmem device (NUMA node 3)
will be picked as 4. After the fix, we get the correct numa node which
is 5.
Fixes: da1115fdbd6e ("powerpc/nvdimm: Pick nearby online node if the device node is not online")
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://msgid.link/20230404041433.1781804-1-aneesh.kumar@xxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index b44ce71917d75..16cfe56be05bb 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -366,6 +366,7 @@ void update_numa_distance(struct device_node *node)
WARN(numa_distance_table[nid][nid] == -1,
"NUMA distance details for node %d not provided\n", nid);
}
+EXPORT_SYMBOL_GPL(update_numa_distance);
/*
* ibm,numa-lookup-index-table= {N, domainid1, domainid2, ..... domainidN}
diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
index 2f8385523a132..1a53e048ceb76 100644
--- a/arch/powerpc/platforms/pseries/papr_scm.c
+++ b/arch/powerpc/platforms/pseries/papr_scm.c
@@ -1428,6 +1428,13 @@ static int papr_scm_probe(struct platform_device *pdev)
return -ENODEV;
}
+ /*
+ * open firmware platform device create won't update the NUMA
+ * distance table. For PAPR SCM devices we use numa_map_to_online_node()
+ * to find the nearest online NUMA node and that requires correct
+ * distance table information.
+ */
+ update_numa_distance(dn);
p = kzalloc(sizeof(*p), GFP_KERNEL);
if (!p)
