x86: fix system without memory on node0
Jack found a boot crash on a system which doesn't have memory on node0. It turns out with recent per_cpu changes, node_number for BSP will always be 0, and it is not consistent to cpu_to_node() that might set it to a different (nearer) node already. aka when numa_set_node() for node0 is called early before per_cpu area is setup: two places touched that per_cpu(node_number,): 1. in cpu/common.c::cpu_init() and it is not for BP | #ifdef CONFIG_NUMA | if (cpu != 0 && percpu_read(node_number) == 0 && | cpu_to_node(cpu) != NUMA_NO_NODE) | percpu_write(node_number, cpu_to_node(cpu)); | #endif for BP: traps_init ==> cpu_init for AP: start_secondary ==> cpu_init 2. cpu/intel.c or amd.c::srat_detect_node via numa_set_node() for BP: check_bugs ==> identify_boot_cpu ==> identify_cpu() that is rather later before numa_node_id() is used for BP... for AP: start_secondary => smp_callin => smp_store_cpu_info() => => identify_secondary_cpu => identify_cpu() so try to set that for BP earlier in setup_per_cpu_areas(), and don't bother to set that for APs there (it will be updated later and will be used later) (and don't mess the 0 before the copying BP per_cpu data to APs) [ Impact: fix boot crash on memoryless node-0 ] Reported-and-tested-by: NJack Steiner <steiner@sgi.com> Cc: Tejun Heo <htejun@gmail.com> Signed-off-by: NYinghai Lu <yinghai@kernel.org> LKML-Reference: <4A0C4A02.7050401@kernel.org> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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