On Thu, 23 Jan 2014, Tang Chen wrote:
> 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:
>
> dump_stack
> panic
> ? numa_clear_kernel_node_hotplug
> __stack_chk_fail
> numa_clear_kernel_node_hotplug
> ? memblock_search_pfn_nid
> ? __early_pfn_to_nid
> numa_init
> x86_numa_init
> initmem_init
> setup_arch
> start_kernel
>
> This patch fix this problem by defining numa_kernel_nodes as a
> static global variable in __initdata area.
>
> Reported-by: Dave Jones <da...@redhat.com>
> Signed-off-by: Tang Chen <tangc...@cn.fujitsu.com>
> Tested-by: Gu Zheng <guz.f...@cn.fujitsu.com>
I guess it depends on what Dave's CONFIG_NODES_SHIFT is?
> ---
> 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;
>
Isn't this also a bugfix since you never initialize numa_kernel_nodes when
it's allocated on the stack with NODE_MASK_NONE?
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