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Date:      Tue, 05 Oct 2010 00:51:57 -0500
From:      Alan Cox <alc@rice.edu>
To:        Dave Hayes <dave@jetcafe.org>
Cc:        alc@freebsd.org, freebsd-stable <freebsd-stable@freebsd.org>
Subject:   Re: Panic: attempted pmap_enter on 2MB page
Message-ID:  <4CAABCFD.6050709@rice.edu>
In-Reply-To: <201010040512.o945CTor092854@hugeraid.jetcafe.org>
References:  <201010030211.o932Bd4C048116@hugeraid.jetcafe.org> <AANLkTikenQoA7UBo_N3bzQJ9ABJSTGL89_Qda_Tu7Wa0@mail.gmail.com> <201010040512.o945CTor092854@hugeraid.jetcafe.org>

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Dave Hayes wrote:
> Alan Cox <alan.l.cox@gmail.com> writes:
>   
>> I'm afraid that I can't offer much insight without a stack trace.  At
>> initialization time, we map the kernel with 2MB pages.  I suspect that
>> something within the kernel is later trying to change one those mappings.
>> If I had to guess, it's related to the mfs root.
>>     
>
> Here is the stack trace. The machine is sitting here in KDB if you
> need me to extract any information from it. I
>
>   db> bt
>   Tracing pid 0 tid 0 td 0xffffffff80c67140
>   kdb_enter() at kdbenter+0x3d
>   panic() at panic+0x17b
>   pmap_enter() at pmap_enter+0x641
>   kmem_malloc() at kmem_malloc+0x1b5
>   uma_large_malloc() at uma_large_malloc+0x4a
>   malloc() at malloc+0xd7
>   acpi_alloc_wakeup_handler() at acpi_alloc_wakeup_handler+0x82
>   mi_startup() at mi_startup+0x59
>   btext() at btext+0x2c
>   db>
>
>   

Thanks.

There are two pieces of information that might be helpful: the value of 
the global variable "kernel_vm_end" and the virtual address that was 
passed to pmap_enter().

Is this problem reproducible?  I don't recall if you mentioned that earlier.

Can you take a crash dump?

Alan




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