On Sat, 26 Mar 2011, Christoph Lameter wrote:
> Tejun: Whats going on there? I should be getting offsets into the per cpu
> area and not kernel addresses.
Its a UP kernel running on dual Athlon. So its okay ... Argh.... The
following patch fixes it by using the fallback code for cmpxchg_double:
Subject: per_cpu: Fixup cmpxchg_double for !SMP
cmpxchg_double should only be provided for SMP. In the UP case
the GS register is not defined and the function will fail.
Signed-off-by: Christoph Lameter <cl@xxxxxxxxx>
Index: linux-2.6/arch/x86/include/asm/percpu.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/percpu.h 2011-03-26 11:11:19.175244998 -0500
+++ linux-2.6/arch/x86/include/asm/percpu.h 2011-03-26 14:45:29.254088998 -0500
@@ -507,6 +507,7 @@
* it in software. The address used in the cmpxchg16 instruction must be
* aligned to a 16 byte boundary.
*/
+#ifdef CONFIG_SMP
#define percpu_cmpxchg16b_double(pcp1, o1, o2, n1, n2) \
({ \
char __ret; \
@@ -529,6 +530,7 @@
#define irqsafe_cpu_cmpxchg_double_8(pcp1, pcp2, o1, o2, n1, n2) percpu_cmpxchg16b_double(pcp1, o1, o2, n1, n2)
#endif
+#endif
/* This is not atomic against other CPUs -- CPU preemption needs to be off */
#define x86_test_and_clear_bit_percpu(bit, var) \
--
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