[PATCH] numa, mem-hotplug: Fix stack overflow in numa when seting kernel nodes to unhotpluggable.

From: Tang Chen
Date: Thu Jan 23 2014 - 00:46:57 EST

Dave found that the kernel will hang during boot. This is because
the nodemask_t type stack variable numa_kernel_nodes is large enough
to overflow the stack.

This doesn't always happen. According to Dave, this happened once
in about five boots. The backtrace is like the following:

? numa_clear_kernel_node_hotplug
? memblock_search_pfn_nid
? __early_pfn_to_nid

This patch fix this problem by defining numa_kernel_nodes as a
static global variable in __initdata area.

Reported-by: Dave Jones <davej@xxxxxxxxxx>
Signed-off-by: Tang Chen <tangchen@xxxxxxxxxxxxxx>
Tested-by: Gu Zheng <guz.fnst@xxxxxxxxxxxxxx>
arch/x86/mm/numa.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
index 81b2750..ebefeb7 100644
--- a/arch/x86/mm/numa.c
+++ b/arch/x86/mm/numa.c
@@ -562,10 +562,10 @@ static void __init numa_init_array(void)

+static nodemask_t numa_kernel_nodes __initdata;
static void __init numa_clear_kernel_node_hotplug(void)
int i, nid;
- nodemask_t numa_kernel_nodes;
unsigned long start, end;
struct memblock_type *type = &memblock.reserved;


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