Messages in this thread Patch in this message |  | | | Date | Fri, 18 May 2012 14:16:07 -0700 | | From | Greg KH <> | | Subject | [ 08/54] ARM: 7414/1: SMP: prevent use of the console when using idmap_pgd |
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3.0-stable review patch. If anyone has any objections, please let me know.
------------------ From: Colin Cross <ccross@android.com>
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>
--- 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 @@ -279,8 +279,6 @@ 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. @@ -292,6 +290,8 @@ 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();
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