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SubjectRe: [PATCH] x86: fix system without memory on node0

* Yinghai Lu <yinghai@kernel.org> wrote:

> Jack found that crash with doesn't have memory on node0.
>
> it turns out with per_cpu changeset, node_number for BSP will be
> alway 0, and it is consistent to cpu_to_node() that is to near
> node already. aka when numa_set_node() for node0 is called early
> before per_cpu area is setup
>
> try to set the node_number for boot cpu, after we get per_cpu area
> setup.
>
> [ Impact: fix crashing on memoryless node 0]
>
> Reported-by: Jack Steiner <steiner@sgi.com>
> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
>
> ---
> arch/x86/kernel/setup_percpu.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> Index: linux-2.6/arch/x86/kernel/setup_percpu.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/setup_percpu.c
> +++ linux-2.6/arch/x86/kernel/setup_percpu.c
> @@ -423,6 +423,14 @@ void __init setup_per_cpu_areas(void)
> early_per_cpu_ptr(x86_cpu_to_node_map) = NULL;
> #endif
>
> +#if defined(CONFIG_X86_64) && defined(CONFIG_NUMA)
> + /*
> + * make sure boot cpu node_number is right, when boot cpu is on the
> + * node that doesn't have mem installed
> + */
> + per_cpu(node_number, boot_cpu_id) = cpu_to_node(boot_cpu_id);
> +#endif

ok, that's a nice fix i guess.

Wouldnt it also be necessary/good to unify this code between 32-bit
and 64-bit? 32-bit has cpu_to_node_map[], while 64-bit has percpu
variables for that.

Ingo


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