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Subject[tip:x86/urgent] x86, numa: Fix numa_emulation code with memory-less node0
Commit-ID:  3b28cf32cc32594710590685ee478f697ed4f328
Gitweb: http://git.kernel.org/tip/3b28cf32cc32594710590685ee478f697ed4f328
Author: Yinghai Lu <yinghai@kernel.org>
AuthorDate: Wed, 2 Mar 2011 15:14:58 -0800
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Fri, 4 Mar 2011 15:20:19 +0100

x86, numa: Fix numa_emulation code with memory-less node0

This crash happens on a system that does not have RAM on node0.

When numa_emulation is compiled in, and:

1. we boot the system without numa=fake...
2. or we boot the system with numa=fake=128 to make emulation fail

we will get:

[ 0.076025] ------------[ cut here ]------------
[ 0.080004] kernel BUG at arch/x86/mm/numa_64.c:788!
[ 0.080004] invalid opcode: 0000 [#1] SMP
[...]

need to use early_cpu_to_node() directly, because cpu_to_apicid
and apicid_to_node will return node0 that is not onlined.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: David Rientjes <rientjes@google.com>
LKML-Reference: <4D6ECF72.5010308@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
arch/x86/mm/numa_64.c | 6 +-----
1 files changed, 1 insertions(+), 5 deletions(-)

diff --git a/arch/x86/mm/numa_64.c b/arch/x86/mm/numa_64.c
index 95ea155..1337c51 100644
--- a/arch/x86/mm/numa_64.c
+++ b/arch/x86/mm/numa_64.c
@@ -780,11 +780,7 @@ void __cpuinit numa_add_cpu(int cpu)
int physnid;
int nid = NUMA_NO_NODE;

- apicid = early_per_cpu(x86_cpu_to_apicid, cpu);
- if (apicid != BAD_APICID)
- nid = apicid_to_node[apicid];
- if (nid == NUMA_NO_NODE)
- nid = early_cpu_to_node(cpu);
+ nid = early_cpu_to_node(cpu);
BUG_ON(nid == NUMA_NO_NODE || !node_online(nid));

/*

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