[PATCH] mempolicy: fix div-by-zero in alloc_pages_bulk_interleave

[Liu Jing]

In alloc_pages_bulk_interleave(), nodes_weight(pol->nodes) may return
0 if all nodes in the policy mask have been offlined at runtime. The
subsequent division "nr_pages / nodes" triggers a divide-by-zero
panic.

Add a zero check returning 0 (no pages allocated) when the nodemask
is empty, consistent with the guard in
alloc_pages_bulk_weighted_interleave().

Signed-off-by: Liu Jing <liujing@xxxxxxxxxxxxxxxxxxxx>
---
 mm/mempolicy.c | 3 +++
 1 file changed, 3 insertion(+), 0 deletion(-)

--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -2600,6 +2600,9 @@
 	unsigned long total_allocated = 0;
 
 	nodes = nodes_weight(pol->nodes);
+	if (!nodes)
+		return 0;
+
 	nr_pages_per_node = nr_pages / nodes;
 	delta = nr_pages - nodes * nr_pages_per_node;
 

--
2.43.0