linux-kernel - [tip:x86/urgent] x86, numa: Fix numa_emulation code with memory-less node0

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Message-ID: <tip-3b28cf32cc32594710590685ee478f697ed4f328@git.kernel.org>
Date:	Fri, 4 Mar 2011 14:31:15 GMT
From:	tip-bot for Yinghai Lu <yinghai@...nel.org>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
	yinghai@...nel.org, tj@...nel.org, tglx@...utronix.de,
	rientjes@...gle.com, mingo@...e.hu
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@...nel.org>
AuthorDate: Wed, 2 Mar 2011 15:14:58 -0800
Committer:  Ingo Molnar <mingo@...e.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@...nel.org>
Acked-by: Tejun Heo <tj@...nel.org>
Cc: David Rientjes <rientjes@...gle.com>
LKML-Reference: <4D6ECF72.5010308@...nel.org>
Signed-off-by: Ingo Molnar <mingo@...e.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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