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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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