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Subject[012/139] sh: Enable the mmu in start_secondary()
2.6.33-stable review patch.  If anyone has any objections, please let us know.


From: Matt Fleming <>

commit 4bea3418c737891894b9d3d3e9f8bbd67d66fa38 upstream.

For the boot, enable_mmu() is called from setup_arch() but we don't call
setup_arch() for any of the other cpus. So turn on the non-boot cpu's
mmu inside of start_secondary().

I noticed this bug on an SMP board when trying to map I/O memory
(smsc911x registers) into the kernel address space. Since the Address
Translation bit in MMUCR wasn't set, accessing the virtual address where
the smsc911x registers were supposedly mapped actually performed a
physical address access.

Signed-off-by: Matt Fleming <>
Signed-off-by: Paul Mundt <>
Signed-off-by: Greg Kroah-Hartman <>

arch/sh/kernel/smp.c | 1 +
1 file changed, 1 insertion(+)

--- a/arch/sh/kernel/smp.c
+++ b/arch/sh/kernel/smp.c
@@ -69,6 +69,7 @@ asmlinkage void __cpuinit start_secondar
unsigned int cpu;
struct mm_struct *mm = &init_mm;

+ enable_mmu();
current->active_mm = mm;

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