This patch add nid sanity check on alloc_pages_node().
While two process change nr_hugepages at a system, alloc_fresh_huge_page()
been called, at this function, nid defined as a static variable, but, there
is not any protection of, if 2 process called at the same time, maybe pass a
invalid nid to alloc_pages_node.
We have hit it by following scripts:
#!/bin/bash
while : ; do
echo 1000000000000 > /proc/sys/vm/nr_hugepages
echo 1 > /proc/sys/vm/nr_hugepages
echo 10000000000000000000 > /proc/sys/vm/nr_hugepages
echo 0 > /proc/sys/vm/nr_hugepages
done
Run the script at _two_ difference terminal, after a short time, a kernel panic
info will print.
Signed-off-by: Joe Jin <[email protected]>
---
--- linux-2.6.22/include/linux/gfp.h.orig 2007-07-12 15:06:23.000000000 +0800
+++ linux-2.6.22/include/linux/gfp.h 2007-07-12 15:02:59.000000000 +0800
@@ -133,6 +133,9 @@
/* Unknown node is current node */
if (nid < 0)
nid = numa_node_id();
+
+ if (unlikely(nid == MAX_NUMNODES))
+ nid = first_node(node_online_map);
return __alloc_pages(gfp_mask, order,
NODE_DATA(nid)->node_zonelists + gfp_zone(gfp_mask));
-
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