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authorColin Cross <ccross@android.com>2012-05-05 20:58:13 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-05-12 09:32:17 -0700
commitc35fda8ad637d6f86fad00139f7faaf3d1133302 (patch)
parent246301f454256967c5845a3e076c05ce488ff910 (diff)
ARM: 7414/1: SMP: prevent use of the console when using idmap_pgd
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 <ccross@android.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index cdeb727527d3..31c256787d62 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -255,8 +255,6 @@ asmlinkage void __cpuinit secondary_start_kernel(void)
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_start_kernel(void)
enter_lazy_tlb(mm, current);
+ printk("CPU%u: Booted secondary processor\n", cpu);