From 084189a88754d40e1bb9bfbc278e70c33e571685 Mon Sep 17 00:00:00 2001
From: Richard Weinberger <richard@nod.at>
Date: Thu, 14 Apr 2011 15:22:18 -0700
Subject: um: disable CONFIG_CMPXCHG_LOCAL

Commit 8a5ec0ba "Lockless (and preemptless) fastpaths for slub" makes use
of this_cpu_cmpxchg_double() which needs this_cpu_cmpxchg16b_emu() on
x86_64.  Implementing cmpxchg16b emulation for UML would introduce too
much complexity.  So just disable it.

Signed-off-by: Richard Weinberger <richard@nod.at>
Reported-by: Sergei Trofimovich <slyich@gmail.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 arch/um/Kconfig.x86 | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/um/Kconfig.x86 b/arch/um/Kconfig.x86
index 02fb017fed47..a9da516a5274 100644
--- a/arch/um/Kconfig.x86
+++ b/arch/um/Kconfig.x86
@@ -4,6 +4,10 @@ menu "UML-specific options"
 
 menu "Host processor type and features"
 
+config CMPXCHG_LOCAL
+	bool
+	default n
+
 source "arch/x86/Kconfig.cpu"
 
 endmenu
-- 
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