[3.13.y-ckt stable] Patch "MIPS: Fix kernel lockup or crash after CPU offline/online" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

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

to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11-ckt17.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 69a9d9c5b02f2e5f01fd93d21f22ffa069f42ddd Mon Sep 17 00:00:00 2001
From: Hemmo Nieminen <hemmo.nieminen at iki.fi>
Date: Thu, 15 Jan 2015 23:01:59 +0200
Subject: MIPS: Fix kernel lockup or crash after CPU offline/online

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 <hemmo.nieminen at iki.fi>
Signed-off-by: Aaro Koskinen <aaro.koskinen at iki.fi>
Cc: David Daney <david.daney at cavium.com>
Cc: linux-mips at linux-mips.org
Cc: linux-kernel at vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/8953/
Signed-off-by: Ralf Baechle <ralf at linux-mips.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 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 0a022ee..18ed112 100644
--- a/arch/mips/kernel/smp.c
+++ b/arch/mips/kernel/smp.c
@@ -109,10 +109,10 @@ asmlinkage void start_secondary(void)
 	else
 #endif /* CONFIG_MIPS_MT_SMTC */
 	cpu_probe();
-	cpu_report();
 	per_cpu_trap_init(false);
 	mips_clockevent_init();
 	mp_ops->init_secondary();
+	cpu_report();

 	/*
 	 * XXX parity protection should be folded in here when it's converted
--
1.9.1