This is a note to let you know that I've just added the patch titled
ARM: 7414/1: SMP: prevent use of the console when using idmap_pgd
to the 3.3-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm-7414-1-smp-prevent-use-of-the-console-when-using-idmap_pgd.patch
and it can be found in the queue-3.3 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From fde165b2a29673aabf18ceff14dea1f1cfb0daad Mon Sep 17 00:00:00 2001
From: Colin Cross <[email protected]>
Date: Sat, 5 May 2012 20:58:13 +0100
Subject: ARM: 7414/1: SMP: prevent use of the console when using idmap_pgd
From: Colin Cross <[email protected]>
commit fde165b2a29673aabf18ceff14dea1f1cfb0daad upstream.
Commit 4e8ee7de227e3ab9a72040b448ad728c5428a042 (ARM: SMP: use
idmap_pgd for mapping MMU enable during secondary booting)
switched secondary boot to use idmap_pgd, which is initialized
during early_initcall, instead of a page table initialized during
__cpu_up. This causes idmap_pgd to contain the static mappings
but be missing all dynamic mappings.
If a console is registered that creates a dynamic mapping, the
printk in secondary_start_kernel will trigger a data abort on
the missing mapping before the exception handlers have been
initialized, leading to a hang. Initial boot is not affected
because no consoles have been registered, and resume is usually
not affected because the offending console is suspended.
Onlining a cpu with hotplug triggers the problem.
A workaround is to the printk in secondary_start_kernel until
after the page tables have been switched back to init_mm.
Signed-off-by: Colin Cross <[email protected]>
Signed-off-by: Russell King <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
arch/arm/kernel/smp.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -255,8 +255,6 @@ asmlinkage void __cpuinit secondary_star
struct mm_struct *mm = &init_mm;
unsigned int cpu = smp_processor_id();
- printk("CPU%u: Booted secondary processor\n", cpu);
-
/*
* All kernel threads share the same mm context; grab a
* reference and switch to it.
@@ -268,6 +266,8 @@ asmlinkage void __cpuinit secondary_star
enter_lazy_tlb(mm, current);
local_flush_tlb_all();
+ printk("CPU%u: Booted secondary processor\n", cpu);
+
cpu_init();
preempt_disable();
trace_hardirqs_off();
Patches currently in stable-queue which might be from [email protected] are
queue-3.3/arm-7414-1-smp-prevent-use-of-the-console-when-using-idmap_pgd.patch
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