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MIPS: Fix kernel lockup or crash after CPU offline/online

Subject: MIPS: Fix kernel lockup or crash after CPU offline/online
From: Hemmo Nieminen <>
Date: Thu, 15 Jan 2015 23:01:59 +0200
commit c7754e75100ed5e3068ac5085747f2bfc386c8d6 upstream.

As printk() invocation can cause e.g. a TLB miss, printk() cannot be
called before the exception handlers have been properly initialized.
This can happen e.g. when netconsole has been loaded as a kernel module
and the TLB table has been cleared when a CPU was offline.

Call cpu_report() in start_secondary() only after the exception handlers
have been initialized to fix this.

Without the patch the kernel will randomly either lockup or crash
after a CPU is onlined and the console driver is a module.

Signed-off-by: Hemmo Nieminen <>
Signed-off-by: Aaro Koskinen <>
Cc: David Daney <>
Signed-off-by: Ralf Baechle <>
Signed-off-by: Luis Henriques <>
 arch/mips/kernel/smp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
index 9bad52ede903..9bc3561b6901 100644
--- a/arch/mips/kernel/smp.c
+++ b/arch/mips/kernel/smp.c
@@ -101,10 +101,10 @@ asmlinkage void start_secondary(void)
        unsigned int cpu;

-       cpu_report();
+       cpu_report();

         * XXX parity protection should be folded in here when it's converted

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