[PATCH] mempolicy: fix mod-by-zero in weighted_interleave_nid

[Liu Jing]

In weighted_interleave_nid(), if the iw_table contains all-zero
weights for every node in the policy nodemask, weight_total sums to
zero. The subsequent "ilx % weight_total" triggers a divide-by-zero
panic.

Add a zero check returning the current NUMA node id when the total
weight is zero, consistent with the existing !nr_nodes guard.

Signed-off-by: Liu Jing <liujing@xxxxxxxxxxxxxxxxxxxx>
---
 mm/mempolicy.c | 4 ++++
 1 file changed, 4 insertion(+), 0 deletion(-)

--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -2218,6 +2218,10 @@
 	/* calculate the total weight */
 	for_each_node_mask(nid, nodemask)
 		weight_total += table ? table[nid] : 1;
+
+
+	if (!weight_total)
+		return numa_node_id();
 
 	/* Calculate the node offset based on totals */
 	target = ilx % weight_total;

--
2.43.0